protein overfeeding

1Human Diet and Purposeful Drugs, College of Western States, Portland, OR, USA

2Department of Well being and Human Efficiency, Nova Southeastern College, Davie, FL, USA

 

Summary

 

INTRODUCTION

Intentional overfeeding or consuming extra energy than required to take care of body weight is a typical follow amongst athletes, particularly bodybuilders, trying to improve their skeletal muscle mass. When mixed with resistance coaching geared toward selling skeletal muscle hypertrophy, a managed part of overfeeding is sometimes called “bulking.” Often, the aim of bulking is to maximise positive factors in skeletal muscle mass whereas minimizing positive factors in fats mass.

Though it’s nicely established that overfeeding causes weight acquire, comparatively little analysis has been performed that evaluates modifications in physique composition. To this point, solely 25 overfeeding research have reported modifications in fats mass (FM) and fat-free mass (FFM) separate from modifications in physique weight (desk 1).

13 of the 25 research adopted an analogous research design: a single group of people had their power necessities or ordinary meals consumption decided at baseline and had been then overfed a set quantity of power or an quantity of power proportional to their baseline consumption. Physique composition measurements had been taken earlier than and after the intervention. The remaining 12 research in contrast two or extra overfeeding remedies offering completely different macronutrient compositions, power surpluses, and meals sources. All however 4 research had been performed in sedentary populations.

The aim of this narrative overview is to look at the present overfeeding literature that stories modifications in physique composition and formulate suggestions for athletes trying to improve lean physique mass. Data gaps within the out there proof and future analysis priorities may also be recognized.

 

EFFECTS OF OVERFEEDING WITH A WESTERN DIET

Ten research have evaluated the impact on physique composition of overfeeding with a food plan reasonably excessive in each carbohydrates and fat (35–50 % power consumption every) and low in protein (11–15 %). All research concerned a single group of sedentary adults and lasted between 9 days and three months. Meals consumption was strictly managed in each research aside from Ernersson et al., which used meals logs for dietary evaluation (16).

Three research overfed contributors by 1,000 kcal per day during the research no matter power necessities for weight upkeep, that means that the diploma of power surplus was variable from individual to individual.(10, 28, 34)

Poehlman et al.(27) recruited six sedentary pairs (12 contributors) of male monozygotic twins and overfed them by 1,000 kcal for 22 days with a food plan that was 15% protein (2.4 g/kg), 35% fats, and 50% carbohydrate. Individuals had been housed in a hospital and underneath 24-hour supervision during the research. All contributors had their power expenditure at relaxation and through widespread sedentary duties (sitting, standing, and gradual strolling) measured through oblique calorimetry to find out whole each day power wants, of which a further 1,000 kcal was added for the overfeeding part of the research. Meals was offered at three meals per day and primarily based on the dietary preferences of the contributors. The typical physique weight acquire was 2.2 kg, of which 50% was FM. Nevertheless, there was appreciable variability within the response to overfeeding. It’s notable that some people misplaced FM and decreased their physique fats share regardless of consuming a further 1,000 kcal per day. Furthermore, there was a big genotype-overfeeding interplay for modifications in physique weight, FM, and FFM, suggesting that genetics do play a task in figuring out physique composition modifications in response to overfeeding.

In a follow-up research by the identical lab, Bouchard et al.(10) repeated the experiment with 12 sedentary pairs (24 contributors) of male monozygotic twins and an extended therapy length (100 days). Individuals had been overfed by 1,000 kcal per day (15% protein, 35% fats, and 50% carbohydrate) offered at three meals and one night snack. Vitality necessities for every participant had been decided over a 14-day interval previous to overfeeding during which dietary consumption underneath situations of secure physique weight was recorded and analyzed. Physique weight elevated considerably by a median of 8.1 kg, of which 67% was FM. Appreciable variation in response to overfeeding was once more famous, however this variation was not distributed randomly among the many 24 contributors. Relatively, important genotype-overfeeding interactions confirmed that within-pair correlations had been reasonable to sturdy for modifications in physique weight (r=0.55), FM (r=0.50), subcutaneous fats (r=0.47), whole visceral fats (r=0.72), and p.c acquire in visceral fats (r=0.90). The within-pair correlation for FFM was not important (r=0.40). These findings additional strengthen the argument that genetics play a task in physique composition modifications throughout overfeeding, particularly because it pertains to fats acquire and the place the fats is saved. Visceral fats acquire seems to have an particularly sturdy genetic element.

Roberts et al.(35) recruited seven sedentary males and overfed them by 1,000 kcal for 20 days on a food plan that was 11% protein (1.5 g/kg), 43% fats, and 46% carbohydrate. Though the contributors had been free-living, the analysis lab offered all meals with no less than one meal per day being consumed underneath researcher supervision. Individuals ate three meals and one night snack per day with 25% of power necessities being consumed at breakfast and the rest partitioned between the opposite two meals and snack. Vitality necessities for every participant had been decided over a 10-day interval previous to overfeeding during which dietary consumption underneath situations of secure physique weight had been recorded and analyzed. Throughout overfeeding, the extra 1,000 kcal was offered from sherbet, fruit juices, margarine, corn oil, and cookies, with 25% consumed at breakfast and the rest cut up between the opposite consuming events. The typical acquire in physique weight was 2.5 kg, of which 68% was FM. Nevertheless, some contributors gained as little as 0.25 kg whereas others gained 2.8 kg. The variations in weight acquire between people had been linearly associated to physique fats modifications (r=0.92; p<0.01), suggesting that elevated FM is primarily liable for physique weight acquire with overfeeding. Whereas the abovementioned research fed all contributors a flat surplus of power no matter power necessities, the remaining seven research established a baseline ordinary power consumption or power requirement to take care of weight after which overfed by 40–70 % of this baseline. Johannsen et al.(20) used the smallest surplus amongst these research. Twenty-nine wholesome males had been overfed by 40% of their power necessities for 8 weeks on a food plan that was 15% protein (1.8 g/kg), 44% fats, and 41% carbohydrate. The contributors had been free-living however consumed all meals (three per day) underneath researcher supervision. Vitality necessities had been decided throughout a two-week interval previous to overfeeding with the usage of doubly-labeled water. Common weight acquire was 7.6 kg, of which 55% was FM. Norgan and Durnin (24) recruited six wholesome males and overfed them by 50% of their power necessities for 9 weeks on a food plan that was 12% protein (2.2 g/kg physique weight), 43% fats, 38% carbohydrate, and seven% alcohol. Notably, that is the one research during which alcohol was included as a part of the overfeeding food plan. No info on the distribution of meals consumption all through the day is offered, however the contributors consumed all meals underneath researcher supervision. Physique weight elevated by a median of 6 kg, of which 62% was FM. The researchers additionally noticed a 1.8 kg improve in physique water content material, which represented 30% of the rise in physique weight and suggests that almost all of positive factors in FFM are probably because of a rise in water content material relatively than precise skeletal muscle tissue. Ravussin et al. (32) overfed 5 wholesome males by 60% of their power necessities for 9 days on a food plan that was 15% protein (2.1 g/kg), 40% fats, and 45% carbohydrate. Vitality necessities had been decided over a two-week baseline part throughout which dietary intakes underneath situations of secure physique weight had been recorded. The contributors ate three meals per day underneath researcher supervision. Physique weight elevated by 3.2 kg, of which 56% was FM. Cornford et al.(15) overfed seven males and two girls by 70% of their power necessities for 2 weeks on a food plan that was 15% protein (1.9 g/kg), 35% fats, and 50% carbohydrate. The contributors had been confined to a hospital during the research and had power necessities decided throughout a one-week baseline interval. In contrast to earlier analysis that offered meals amongst 3–4 meals per day, this research distributed meals amongst three meals and 4 snacks between 8:00 am and 10:00 pm, thus requiring that contributors eat each 2–3 hours. Physique weight considerably elevated by 2.1 kg, of which 67% was FM. Salans et al.(38) recruited 5 wholesome male inmates of the Vermont State Jail and overfed them an unspecified power surplus with unknown macronutrient composition for 3 to 4 months. Vitality necessities had been decided throughout a six-week baseline interval during which meals consumption was manipulated till physique weight remained secure. The typical improve in physique weight was 16.2 kg or 1.0 to 1.3 kg per week, suggesting that the power surplus was fairly substantial, and FM represented 64% of the acquire in physique weight. Tchoukalova et al.(45) overfed 15 males and 13 girls for eight weeks on a managed weight upkeep food plan (15% protein, 35% fats, and 50% carbohydrate) supplemented with extra power from ice cream, chocolate nougat sweet bars, and dietary shakes. Nevertheless, no info on the magnitude of the power surplus or the macronutrient composition of the overfeeding food plan was offered. The contributors had been “instructed to increase their overall food intake by eating until they were more full than usual.” Physique weight considerably elevated by 4.6 kg, of which 83% was FM. Intercourse didn't have an effect on the response to overfeeding. That is essentially the most unfavorable change in physique composition but. Though no overfeeding macronutrient knowledge is offered, it's probably that protein consumption was particularly low contemplating that baseline consumption was solely 15% of power consumption and overfeeding was on meals low in protein content material. Moreover, the present research utilized what many would think about “junk food” throughout overfeeding (excessive in fat and sugars); subsequently, this will likely have influenced the modifications in physique composition. Lastly, work by Ernersson et al.(16) was the one research to not management meals consumption and as an alternative measured dietary consumption through three-day meals logs. Twelve male and 6 feminine contributors had been “prescribed to double their energy intake during the intervention, by eating at least two fast food based meals per day” for 4 weeks. This led to a median power surplus of 70% in comparison with ordinary consumption, with a macronutrient composition of 12% protein (2.4 g/kg), 43% fats, and 45% carbohydrate. Notably, 20% of whole power consumption was from sugar and 17% was from saturated fats. Physique weight elevated considerably by 6.4 kg, of which 58% was FM. Moreover, there was a big improve in liver fats from 1.1 to 2.8 % (non-alcoholic fatty liver illness is noticed with 5–10% liver fats) and this improve was considerably related to will increase in physique weight (r=0.44) and particularly physique fats share (r=0.81).(22)

In abstract, overfeeding wholesome, sedentary adults with a food plan reasonably excessive in each carbohydrates and fat (35–50 % power consumption every) and low in protein (11–15 %) primarily leads to a acquire in FM. Though there's variation amongst research, probably owed to variations among the many research populations and the meals used for overfeeding, FM generally represents 60–70 % of the rise in physique weight. Moreover, the will increase in FFM could also be because of will increase in physique water content material relatively than skeletal muscle tissue, as steered by Norgan and Durnin.(24) Contemplating that skeletal muscle requires mechanical rigidity, muscle harm, and metabolic stress for hypertrophy, it isn't unlikely that modifications in physique water accounted for many modifications in FFM among the many sedentary adults in these research.(39) Equally, modifications in organ mass or non-muscle lean tissue may clarify a rise in FFM. It's attention-grabbing to notice that the contributors of Poehlman et al. gained much less FM than these of Roberts et al. (50 vs. 68 % of the acquire in body weight) regardless of an analogous power surplus (1,000 kcal/d), research length (22 and 20 days), and physique weight acquire (2.2 and a pair of.5 kg).(28, 34) A serious distinction between these two research is the protein consumption of the contributors, which was 2.4 g/kg/d in Poehlman et al. and 1.5 g/kg/d in Roberts et al. It's nicely established that increased protein diets improve thermogenesis and promote the accretion of FFM, each of which may clarify the decrease acquire in FM in Poehlman et al.(11, 26, 28) A positive impact on physique composition of a better protein consumption is additional supported by the discovering that contributors from Ernersson et al. gained 58% of their physique weight acquire as FM whereas consuming 2.4 g/kg/d of protein, in comparison with the contributors of Cornford et al. who gained 67% of their physique weight acquire as FM whereas consuming 1.9 g/kg/d of protein, regardless of each research overfeeding by 70% of power necessities.(15, 16) The mentioned research have a number of different notable findings as nicely. Poehlman et al. and Bouchard et al. discovered that modifications in physique composition with overfeeding are partially depending on genetic elements, which might partly clarify the notable variability in physique composition modifications noticed in each overfeeding research mentioned.(10, 28) Roberts et al. discovered that better will increase in physique weight are strongly correlated with better will increase in FM, which suggests that almost all of physique weight acquire in a sedentary inhabitants is attributable to will increase in FM relatively than FFM and that it could not matter how a lot or how shortly weight is gained, as most will probably be fats mass regardless.(34) Ernersson et al. demonstrated that will increase in liver fats concentrations had been strongly correlated with will increase in physique fats share, which raises questions on whether or not elevated liver fats would result in unfavorable modifications in physique composition or vice-versa.(16) This latter discovering by Ernersson et al. is very necessary to follow-up on contemplating that sure dietary practices could preferentially improve liver fats concentrations, similar to overfeeding on sugars and saturated fats.(50) Regardless of these observations, not one of the abovementioned research had been designed to research how completely different dietary elements or participant traits affected modifications in physique composition with overfeeding. Moreover, all of the research used sedentary populations and unrealistic caloric surpluses (baseline power consumption plus 1000 kcal or 40–70% of baseline), making it troublesome if not unimaginable to extrapolate their findings to an athletic inhabitants trying to bulk.  

EFFECTS OF OVERFEEDING ON CARBOHYDRATES VERSUS FATS

Three research have in contrast modifications in physique composition between two teams overfeeding on diets with completely different quantities of fats and carbohydrate. All three research concerned a sedentary inhabitants, used unrealistically massive power surpluses, and lasted two to 3 weeks.

Horton et al. (17) recruited 9 regular weight and 7 overweight males to eat a food plan supplying 150% of power necessities for 2 weeks during which the 50% surplus of power got here totally from carbohydrates or fat in a randomized crossover design. No info on the macronutrient composition of the overfeeding or baseline diets was offered aside from a baseline fats consumption of 35% of power necessities. Nevertheless, a pattern menu of the overfeeding diets was offered, together with the quantity of meals eaten, which allowed for dietary evaluation. Utilizing the Meals Processor Diet Evaluation Software program (ESHA), the high-carbohydrate food plan was 11% protein (1.2 g/kg), 25% fats, and 64% carbohydrate whereas the high-fat food plan was 11% protein (1.2 g/kg), 58% fats, and 31% carbohydrate. Every overfeeding interval was preceded by one week of consuming a baseline upkeep food plan and a four-week washout interval separated the overfeeding durations. All meals was offered to the contributors by the researchers and no less than one meal per day was to be consumed on the analysis facility underneath supervision whereas the rest was packaged to be eaten elsewhere. Physique weight, FM, and FFM elevated considerably on each overfeeding diets with out important distinction between them. Total, FM represented 52% of the acquire in physique weight within the high-carbohydrate group and 58% within the high-fat group. There have been additionally no important variations between lean and overweight contributors.

Lammert et al.(23) recruited 20 normal-weight males and overfed them by 1200 kcal for 3 weeks on a food plan that was both excessive in carbohydrates (11% protein (1.7 g/kg), 11% fats, and 78% carbohydrate) or excessive in fat (11% protein (1.7 g/kg), 58% fats, and 31% carbohydrate) utilizing a parallel-group design. The intervention was preceded by a two-week interval the place contributors recorded ordinary meals consumption underneath free-living situations to ascertain a baseline power consumption. The overfeeding intervention itself was carried out inside a analysis facility the place the contributors had been underneath 24-hour supervision and meals consumption was managed. Each teams considerably elevated their physique weight and FM with no between-group variations. The high-carbohydrate group considerably elevated FFM, though this was not considerably completely different from the high-fat group. Total, the proportion of physique weight acquire that was FM was 57% within the high-carbohydrate group and 69% within the high-fat group.

Lastly, Claesson et al. (14) randomized 25 normal-weight women and men to eat 20 kcal/kg/day of sweet or roasted and salted peanuts along with their common food plan for 2 weeks utilizing a parallel-group design. This led to a median each day power consumption 46% better than ordinary consumption on diets offering 17% protein (2.0 g/kg), 48% fats, and 35% carbohydrate (40 g fiber) with peanuts or 10% protein (1.2 g/kg), 21% fats, and 69% carbohydrate (20 g fiber) with sweet. The contributors had been free-living all through the intervention and equipped with 14 individually adjusted luggage of their respective snack for consumption each day (one bag/d). A 3-day weighed meals log quantified meals consumption at baseline and in the course of the overfeeding interval. No instruction on when to devour the snacks was offered. Solely the sweet group skilled a big improve in physique weight of 0.8 kg, of which 38% was FM. The peanut teams skilled a non-significant improve in physique weight of 0.3 kg, all of which was attributable to a rise in FFM (FM remained unchanged).

The research by Horton et al. and Lammert et al. present the strongest proof for drawing conclusions, as they each managed meals consumption and matched the quantity of protein between diets.(18, 23) Each research confirmed no distinction in physique composition with overfeeding on a food plan excessive in carbohydrates or excessive in fats. Nevertheless, the contributors of Horton et al. consumed 35% of their power consumption as sugar in the course of the high-carbohydrate part, primarily from fruit juices, and consumed 33% of their power consumption as saturated fats, primarily from heavy whipping cream, within the high-fat part.(18) Equally, the high-carbohydrate group from Lammert et al. consumed 29% of their power consumption from purified sucrose.(23) As will probably be mentioned later, overfeeding on saturated fats causes extra FM acquire than unsaturated fats (Rosqvist et al.).(37) Moreover, it stays unknown whether or not overfeeding on whole-food carbohydrate sources similar to fruits, starchy greens, complete grains, and legumes would end in a distinct change in physique composition than overfeeding on refined sugars. The research by Claesson et al. additionally means that there is no such thing as a distinction between overfeeding on a high-fat or high-carbohydrate food plan.(14) Nevertheless, the dearth of management over the food plan and bodily exercise ranges of the contributors precludes drawing agency conclusions, particularly contemplating that the peanut group didn’t considerably change their physique weight regardless of a reported power surplus of 46% per day. Earlier analysis has proven that including peanuts into the food plan end in a decrease consumption of different meals and improve in power expenditure, each of which may clarify the marginal change in physique weight.(3) Moreover, research of walnuts, almonds, and pistachios have demonstrated that these nuts present much less metabolizable power to the physique than what’s predicted primarily based on Atwater elements.(8, 9, 25) It’s potential that a part of the power offered by the peanuts was merely not out there to be used by the physique, subsequently leading to a decrease power surplus than deliberate. Lastly, the peanut group consumed considerably extra protein and fiber than the sweet group, which makes isolating the impact of overfeeding on fats troublesome.

 

EFFECTS OF THE TYPE OF CARBOHYDRATE OR FAT – “protein overfeeding”

Two research have in contrast modifications in physique composition between two teams overfeeding on macronutrient-identical diets differing solely their supply of carbohydrate or fats. Each research concerned a sedentary, free-living inhabitants and had contributors add meals to their ordinary food plan.

Stanhope et al.(43) performed a double-blind, parallel-group research during which 32 obese, sedentary adults had been instructed to devour a sugar-sweetened beverage along with their ordinary food plan for eight weeks. The beverage offered 25% of power necessities within the type of pure glucose or pure fructose. A two-week inpatient interval previous the overfeeding invention was used to ascertain upkeep power necessities. The contributors obtained their beverage provide twice weekly from the analysis lab and had been instructed to drink one-third of the beverage thrice per day with their essential meals. Dietary consumption was decided from the common of six 24-hour meals recollects carried out over the phone. Including the sugar-sweetened drinks into the food plan of the contributors resulted in an power surplus of 8% in comparison with necessities decided at baseline, with a dietary macronutrient composition of 14% protein, 29% fats, and 57% carbohydrate. Each teams skilled important will increase in physique weight (1.3–1.6 kg) and FM (54–56% of the acquire in physique weight); nonetheless, there have been no between group variations. There have been additionally no important variations between teams in whole or subcutaneous belly fats. Nevertheless, the fructose group did have a tendency (p=0.059) to point out a better improve in visceral fats than the glucose group (+ 14 vs. 3.2 %, respectively).

Whereas it could be intriguing to see if an extended therapy interval or bigger pattern dimension would present that consuming fructose (versus glucose) considerably will increase visceral fats, the real-world applicability of those findings is questionable. The quantity of sugar consumed by the topics on this research, 25% of power necessities, is significantly increased than the present estimate for the common consumption of added sugars by People, which vary from 16.3% in younger adults to 11.8% in aged adults.(48) Though no knowledge is obtainable on added sugar consumption in athletes, we’d speculate that athletes would sometimes devour much less sugar than the overall inhabitants. However, this investigation does present that glucose and fructose have differential results on fats distribution, which can affect well being and physique composition over the long run. Following the overfeeding part of Stanhope et al., the contributors had been subjected to a two-week inpatient interval during which dietary consumption and bodily exercise had been strictly managed.(43) Throughout this era, the contributors consumed a upkeep food plan composed of 15% protein, 30% fats, and 55% carbohydrate. Fructose- or glucose-sweetened drinks equipped 25% of the carbohydrate; the remaining 30% got here from starch. It was proven that de novo lipogenesis inside the liver was considerably elevated by 83% in comparison with baseline within the fructose group however was unaltered within the glucose group, which the authors suggest as a proof for the elevated visceral fats from overfeeding on fructose as in comparison with glucose. Moreover, consuming fructose however not glucose considerably decreased insulin sensitivity by 17% and promoted dyslipidemia.

Additional analysis is required to find out if the outcomes of Stanhope et al. are supported with a decrease consumption of fructose, particularly from complete fruit relatively than sugar-sweetened drinks. A minimum of one research has proven that including 7 kcal/kg physique weight per day of fruit (common consumption of 423 kcal) to the food plan for 2 months has no important impact on visceral fats or blood lipids.(2) Nevertheless, power consumption and physique weight had been additionally unaffected, suggesting that the addition of fruit to the food plan resulted in dietary compensation that prevented hypercaloric situations. It subsequently stays unknown what impact fructose from fruit consumption has on physique composition and fats distribution when overfeeding.

Rosqvist et al. (36) performed the second research: a seven-week, double-blind, randomized managed trial with parallel-group design involving 37 sedentary, free-living adults. The contributors had been instructed to devour muffins baked utilizing sunflower oil excessive within the polyunsaturated omega-6 fatty acid: linoleic acid or utilizing palm oil excessive within the saturated fatty acid: palmitic acid. Muffins had been added to the ordinary food plan and the quantity was individually adjusted to attain a 3% weight acquire over the seven-week intervention. Dietary consumption was assessed by four-day weighed meals data at baseline and week seven. On common, each teams consumed three muffins per day offering 750 kcal. Meals data confirmed no important distinction between teams for power or macronutrient consumption. Each teams equally elevated their power consumption by 20–25% and consumed a food plan offering 12% protein (1.4 g/kg), 37–40% fats, and 43–48% carbohydrate. Nevertheless, as per research design, the sunflower oil group consumed considerably extra polyunsaturated fatty acids (13 vs. 4.5 % of power) and considerably much less saturated fats (11.5 vs. 16.5 %) than the palm oil group. Each teams considerably elevated their physique weight, FM, and FFM in comparison with baseline. The rise in physique weight was not considerably completely different between teams. Nevertheless, the sunflower oil group had considerably decrease will increase in FM and better will increase in FFM than the palm oil group. Fats mass represented 50% and 81% of the physique weight acquire within the sunflower and palm oil teams, respectively. Moreover, the palm oil group had considerably better will increase in liver and visceral fats than the sunflower oil group. Adjustments in liver and visceral fats in addition to whole FM had been instantly related to modifications in plasma palmitic acid, whereas liver fats and FM had been inversely related to modifications in plasma linoleic acid. Regardless of comparable weight acquire after overfeeding, this research confirmed that overfeeding on a food plan wealthy in linoleic acid had a extra favorable impact on physique composition and ectopic fats deposition than overfeeding on a food plan wealthy in palmitic acid. The mechanisms behind the differential results on liver and whole fats deposition are unknown, however could contain variations in hepatic lipogenesis and/or fatty acid oxidation and storage.(21) The authors notice that the muffins contained important quantities of fructose (though no knowledge on sugar consumption is offered), and former overfeeding analysis has proven that fructose and saturated fats act synergistically to advertise liver fats accumulation.(41) Accordingly, future work ought to try to duplicate Rosqvist et al.’s findings utilizing low-sugar diets.(37)

It should even be acknowledged that completely different fatty acids inside the identical chemical class elicit completely different physiological responses, thus limiting generalization of those findings.(29) Additional analysis is now wanted to ascertain how palmitic acid and linoleic acid evaluate with different fatty acids similar to medium-chained saturated fatty acids, omega-3 polyunsaturated fatty acids, and the first monounsaturated fatty acid, oleic acid.

 

EFFECTS OF THE MAGNITUDE OF THE CALORIC SURPLUS

The investigation by Siervo et al.(40) is the one one that gives info on how the diploma of power extra throughout overfeeding influences modifications in physique composition.

Six sedentary males had been recruited to partake in a 17-week protocol of progressive overfeeding. The contributors had been challenged with a 20, 40, and 60 % power surplus for 3 weeks every, separated by one-week washout durations. The research started with a three-week baseline interval to ascertain upkeep power necessities. All meals was offered to the contributors as three meals per day. The macronutrient composition of the diets was 12–13 % protein (1.4–1.7 g/kg), 43–48 % fats, and 40–44 % carbohydrate throughout every of the overfeeding phases. Notably, physique composition was assessed utilizing the four-compartment mannequin, the gold-standard methodology of measurement that removes assumptions about physique hydration and bone mineral standing.(49) Physique weight constantly elevated in the course of the overfeeding phases, though statistical significance was achieved solely after the 40 and 60% phases. Comparable observations had been made for FM and FFM, each of which elevated after every part however solely considerably after the 60% part. In the end, FM accounted for 57, 52, and 63 % of the physique weight acquire in the course of the 20, 40, and 60 % overfeeding phases, respectively. Nevertheless, will increase in FFM had been primarily attributable to will increase in whole physique water, which accounted for 61, 79, and 92 % of the FFM will increase in the course of the progressive overfeeding phases.

It’s cheap to hypothesize that the bigger the caloric surplus, the better the rise in water weight. Moreover, proportional positive factors in FM don’t seem like meaningfully altered because the caloric surplus will increase from 20 to 60 %. Nevertheless, Siervo et al. didn’t evaluate the overfeeding phases to at least one one other and had a really small pattern dimension, thus stopping agency conclusions.(40) Relatively, this research offers observations that future analysis ought to examine instantly (e.g., a research during which a number of teams of people are overfed differing quantities of power and in contrast on their modifications in physique composition).

 

EFFECTS OF OVERFEEDING WITH A HIGH-PROTEIN DIET

Seven research have investigated the results of protein overfeeding on physique composition. Two of those research had been performed in sedentary people whereas the rest concerned an athletic inhabitants that underwent a concurrent resistance coaching program.

Webb and Annis recruited 9 sedentary adults to overfeed by 1000 kcal/d for 30 days on a high-protein food plan [20% protein (2.4 g/kg), 50% fat, and 30% carbohydrate], common food plan [14% protein (1.7 g/kg), 41% fat, and 45% carbohydrate], or high-carbohydrate food plan [10% protein (1.2 g/kg), 30% fat, and 60% carbohydrate].(47) Every of the three teams included 4 contributors, with three of the 9 contributors consuming two of the diets and the rest solely being in a single food plan group. The contributors lived at residence however ate all meals underneath researcher supervision. Meals consumption was strictly managed. A 30-day baseline interval previous to overfeeding was used to ascertain upkeep power necessities. The typical and high-carbohydrate diets confirmed comparable will increase in physique weight, FM, and FFM, with FM being 74 and 78 % of the acquire in physique weight of those diets, respectively. Nevertheless, the high-protein food plan gained considerably much less physique weight (1.8 vs. 2.7 kg in each different teams) and FM (1.1 vs. 2.0 kg in each different teams) however comparable FFM, resulting in a FM acquire that was 61% of the acquire in physique weight.

The second sedentary inhabitants research was performed by Bray et al.(12) Utilizing a double-blind, randomized, parallel-group design, 25 sedentary adults had been overfed by 40% of power necessities for eight weeks on diets supplying 5% protein (0.7 g/kg), 15% protein (1.8 g/kg), or 25% protein (3.0 g/kg). Carbohydrate consumption was equal throughout teams (41–42 % power) and fats was decreased to accommodate the growing protein consumption. All through the research, contributors had been confined to a metabolic unit and underneath 24-hour supervision. Meals consumption and bodily exercise had been managed, with meals offered as three meals and one snack. A 13- to 25-day baseline interval was used to ascertain upkeep power necessities. All teams gained a big quantity of physique weight throughout overfeeding, however the low-protein group gained considerably lower than the opposite two teams (3.1 kg vs. 6.0 and 6.5 kg within the regular and high-protein teams, respectively). Nevertheless, all three teams considerably elevated FM to an analogous extent (3.4 to three.7 kg) whereas solely the normal-protein and high-protein teams considerably elevated FFM. The failure to extend FFM within the low protein group accounted for its smaller weight acquire. The truth is, the low-protein group misplaced a non-significant quantity of FFM to the extent that the rise in FM represented 119% of the acquire in physique weight. Against this, the normal- and high-protein teams had a FM acquire of 58 and 52 % the acquire in physique weight, respectively. Primarily based on the regression line of protein consumption and alter in FFM, Bray et al. confirmed that the protein consumption required to stop lack of FFM averaged ~78 g/d (1.05 g/kg), which was 30 g/d (0.35 g/kg) increased than the protein consumption of the low protein group (47.0 g/d; 0.7 g/kg).(12)

Each the above research recommend {that a} increased protein food plan results in a extra helpful change in physique composition with overfeeding. Webb and Annis confirmed that FFM acquire was comparable throughout protein intakes of 1.2, 1.7, and a pair of.4 g/kg.(47) Bray et al. confirmed that the acquire in FFM was comparable with a protein consumption of 1.8 and three.0 g/kg. Thus, the info recommend that FFM requires about 1.05 g/kg to be no less than maintained. It seems that consuming greater than 1.2 g/kg/d of protein has no additional helpful affect on FFM amongst a sedentary inhabitants underneath hypercaloric situations.(12) In distinction to the settlement on FFM, the above research present disparate findings relating to FM. Webb and Annis present that progressing from 1.7 to 2.4 g/kg reduces positive factors in FM whereas 1.2 and 1.7 g/kg have comparable results on FM acquire.(47) But, there was no distinction in FM acquire among the many 1.8 and three.0 g/kg teams from Bray et al.(12) The 40% power surplus from Bray et al. corresponded to about 900 to 980 kcal/d, which isn’t meaningfully completely different from the 1000 kcal/d surplus of Webb and Annis. The research length of Bray et al. was roughly twice the size of Webb and Annis (56 vs. 30 days), however modifications in physique composition confirmed a comparatively linear improve in each research, suggesting that altering the length wouldn’t clarify the discrepancy in FM acquire. Contemplating that solely Bray et al. strictly managed bodily exercise, it’s potential that consuming extra protein results in will increase in spontaneous bodily exercise or non-exercise exercise thermogenesis (NEAT) that will be obvious in Webb and Annis, presumably by means of an impact of protein on neuropeptide concentrations.(46) Alternatively, there could also be an interplay between protein consumption and fats and/or carbohydrate consumption, as each “medium” protein teams from Bray et al. and Webb and Annis had an analogous macronutrient composition, whereas the “high” protein group in Bray et al. consumed 41 and 33 % of power consumption as carbohydrate and fats in comparison with 30 and 50 %, respectively, in Webb and Annis. Regardless, Bray et al. utilized a a lot stronger research design and bigger pattern dimension of each women and men than Webb and Annis, thus placing extra confidence of their discovering that the quantity of dietary protein doesn’t meaningfully affect positive factors in FM amongst an overfeeding sedentary inhabitants.

The remaining 5 “high-protein” research concerned an athletic inhabitants that underwent a resistance coaching program whereas overfeeding. Not one of the research managed meals consumption or bodily exercise and relied on meals logs to find out the dietary consumption of the contributors.

In a double-blind, randomized, parallel-group design, Spillane et al. recruited 21 wholesome, resistance-trained males to overfeed on 1250 kcal of carbohydrates alone (312 g/d maltodextrin) or a mix of carbohydrates and protein (94 g, 196 g, and 22 g of protein, maltodextrin, and fats, respectively) whereas concurrently performing a standardized resistance coaching routine over eight weeks.(42) The contributors consumed the carbohydrate or carbohydrate plus protein dietary supplements along with their common food plan: half consumed inside half-hour earlier than and half-hour after every resistance coaching session, or your entire complement dose upon waking on non-training days. Meals logs accomplished by the contributors confirmed that neither group considerably modified their ordinary food plan in the course of the intervention. When the complement was included within the food plan, the high-protein group consumed 22% protein (2.4 g/kg), 29% fats, and 49% carbohydrate, whereas the carbohydrate solely group consumed 10% protein (1.0 g/kg), 25% fats, and 65% carbohydrate. There have been no important variations between teams for will increase in physique weight, FM, or FFM, however whole physique water content material elevated considerably extra within the high-protein group. Nevertheless, whereas each teams gained an analogous quantity of FM (~1.4 kg), solely the high-protein group gained a big quantity of FFM (2.3 vs. 0.2 kg). In the end, the acquire in FM was ~100% the physique weight positive factors within the carbohydrate solely group in comparison with 37% within the high-protein group. Nonetheless, the acquire in FFM may probably be defined by the rise in physique water and whether or not the rise was owed to water or skeletal muscle protein is unclear. Latest proof reveals that progressive resistance coaching will increase whole physique water by means of an increase in mobile hydration; nonetheless, it’s unclear why whole physique water elevated solely within the high-protein group.(33) Nonetheless, a confounding variable of this investigation is that each teams really overfed totally on carbohydrate. Thus, it’s considerably deceptive to explain a gaggle that’s ‘high’ in protein when in reality it was roughly twice as excessive in carbohydrate content material. Extrapolating the findings of Spillane et al. to an athletic inhabitants trying to bulk is troublesome due to the large power surplus employed, the quantity of carbohydrate consumed (i.e., this was extra of a excessive carbohydrate overfeed) and the dearth of distribution by means of the day.(42) This limitation is essentially overcome by a sequence of research performed by Antonio et al. that used power surpluses and power distribution patterns extra typical amongst athletes trying to achieve lean physique mass.

Antonio et al.(7) examined 30 wholesome women and men with a median of 9 years of resistance coaching expertise. Topics had been randomized into one in every of two teams: devour 4.4 g/kg of protein each day or to take care of present dietary habits for eight weeks. Each teams had been additionally instructed to take care of their present train habits. In comparison with the management group, the high-protein group consumed considerably extra energy (+ 800 kcal) and protein (4.4 vs. 1.8 g/kg) derived primarily from whey protein shakes, resulting in a food plan that was 45% protein, 27% fats, and 30% carbohydrate. There have been no statistically important modifications between teams or inside teams for any of the physique composition variables. Nevertheless, it’s notable that the high-protein group elevated FFM (+1.9 vs. 1.3 kg) and decreased FM (−0.2 vs. +0.3 kg) in comparison with the management group regardless of consuming a further 800 kcal/d.

In a follow-up investigation, Antonio et al. randomized 48 wholesome, resistance-trained women and men to devour a minimal of three g/kg of protein each day or to take care of present dietary habits for eight weeks whereas present process a standardized resistance coaching program designed to extend lean physique mass.(4) In comparison with the management group, the high-protein group consumed considerably extra energy (+ 490 kcal) and protein (3.4 vs. 2.3 g/kg) from primarily whey protein shakes, resulting in a food plan that was 39% protein, 27% fats, and 34% carbohydrate. Each teams considerably elevated FFM and considerably decreased FM in comparison with baseline, however the discount in FM was considerably better within the high-protein group in comparison with the management group (−1.6 vs. −0.3 kg). Accordingly, physique weight acquire was additionally considerably much less within the high-protein group in comparison with the management group.

Furthermore, Antonio et al.(5) performed a randomized, crossover trial during which 12 resistance-trained males consumed a high-protein food plan or their ordinary food plan for eight weeks every. All through the 16-week intervention, the contributors adopted their very own power and conditioning program. In comparison with the management therapy, the high-protein therapy consumed considerably extra energy (+ 370 kcal) and protein (3.3 vs. 2.6 g/kg) from primarily whey protein shakes, resulting in a food plan that was 42% protein, 28% fats, and 30% carbohydrate. There have been no important variations between the management and high-protein remedies for any physique composition variable. Nevertheless, 9 of the 12 contributors confirmed a discount in FM in the course of the high-protein food plan part.

Campbell et al.(1) examined 17 resistance-trained feminine topics that had been matched for whole fats mass and randomized to a high-protein (2.4 g/kg/d) or management group (1.2 g/kg/d) for eight weeks along side a resistance-training program. The high-protein group consumed considerably extra energy (+400 kcal) and protein than the management group, however there have been in any other case no restrictions or pointers positioned on their food plan. The upper protein food plan was proven to be superior to a decrease protein food plan for growing FFM, however each diets equally decreased FM.

The research by Antonio et al. collectively recommend {that a} high-protein food plan could cut back FM if there’s an alteration within the coaching routine; nonetheless, modifications in FFM usually are not completely different between a 2.6 and three.3 g/kg/d protein consumption suggesting there could also be an higher restrict to protein consumption vis a vis positive factors in FFM. Though statistical significance was not achieved in every research, presumably because of massive particular person responses to overfeeding on protein and comparatively small pattern sizes that will have restricted statistical energy, there was a constant statement that consuming above 3 g/kg protein led to reductions in FM in comparison with consuming 2.6 g/kg or much less. Importantly, the comparator food plan in these research could be thought of high-protein by most requirements, so the work of Antonio et al. is evaluating a high-protein food plan to the next protein food plan. Sadly, Antonio et al. didn’t management meals consumption in any of his research, elevating the likelihood that the rise in protein consumption led to a discount in different meals and a decrease power surplus than reported. Nevertheless, the contributors of Antonio et al.’s research had been all athletes who frequently tracked meals consumption of their regular lives and used the MyFitnessPal® smartphone app to log their meals. It subsequently appears unlikely that misreporting would happen. Nonetheless, misreporting error could be anticipated to be randomly distributed among the many teams, thus minimizing its confounding on the research outcomes if it did happen.

The work of Spillane et al. and Campbell et al. seem to distinction the findings of Antonio et al. by exhibiting {that a} high-protein food plan has a helpful impact on FFM in comparison with a low-protein food plan however no impact on FM. Nevertheless, these research in contrast a real high-protein food plan (2.4 g/kg) to true low-protein food plan (1.0–1.2 g/kg), which contrasts with Antonio et al. who in contrast a high-protein food plan (1.8–2.6 g/kg) to the next protein food plan (>3.3 g/kg). As such, the research usually are not in contradiction with each other. It seems that consuming 1.0–1.2 g/kg of protein is just not satisfactory for an athlete to maximise muscle development. It stays unknown how consuming an intermediate quantity of protein (1.6–2.0 g/kg) would honest towards the low- and high-protein diets. Though each Spillane et al. and Campbell et al. discovered no impact of a high-protein food plan on FM in comparison with a low-protein food plan, Spillane et al. reported a big improve in comparison with baseline whereas Campbell et al. reported a non-significant discount. This discrepancy is presumably defined by the distribution of the power surplus being extra even all through the day in Campbell et al.’s research, versus a 600–1200 kcal bolus consumed round coaching or within the morning within the research by Spillane et al. Moreover, the each day power surplus itself was decrease, being a mere 400 kcal in Campbell et al. An evidence for the discount in FM when overfeeding on a high-protein food plan is unclear. It’s potential that will increase in non-exercise exercise thermogenesis or diet-induced thermogenesis with elevated protein consumption performed a task in decreasing FM. Moreover, current animal knowledge recommend {that a} high-protein food plan would possibly cut back fats mass by inhibiting lipogenesis within the liver.(13) The inhibition of lipogenesis is logical contemplating the excessive power price of the metabolic pathways related to protein, together with gluconeogenesis, the urea cycle and excretion of ammonia, and protein synthesis.

“protein overfeeding”