A comparison of the effect of protein vs. carbohydrate consumption on human energy balance in free‐living conditions

Abstract

BackgroundSeveral clinical studies have demonstrated beneficial effects of protein on satiety and reduced energy intake acutely, whereas some evidence suggests carbohydrate consumption may lead to positive energy balance. However, it is unclear if these findings have high external validity, or applicability and effectiveness in free‐living settings. Our objective was therefore to compare the effect of consumption of egg protein to consumption of carbohydrate on energy balance in an ad‐libitum, free‐living setting.MethodsA double blinded, randomized crossover study with a two‐week washout period was conducted. The treatments were mandatory consumption of protein supplied as an egg protein shake (PS) or mandatory consumption of a maltodextrin shake (CS)(23, 32, or 42 g dose with each meal, individualized depending on basal metabolic rate) each for 5 days. The shakes were consumed before breakfast, lunch and dinner. All meals were consumed in a laboratory setting in a buffet format, and food intake was measured covertly by weighing before and after consumption. Physical activity energy expenditure was measured using accelerometers for the entire duration of the treatment period, and satiety and hunger were measured using self‐reported visual analogue scales (VASs). Missing values were addressed via multiple imputation based on available intake data within and across subjects. Changes in energy balance, calculated based on energy intake and total energy expenditure (from resting metabolic rate and accelerometer‐measured physical activity), were compared across PS and CS weeks using a linear mixed effects model, accounting for the crossover design. VAS measures were compared via comparisons of area under the curve (AUC).ResultsThere was no evidence for significant carryover effects in any analysis. Change in energy balance on CS was higher than PS (+115 kcal/week) but this amount is not statistically significant; the corresponding p‐value was always at least p = 0.31 in each of our 1000 imputations. Similarly, subjects reported weekly changes of more hunger (+723 mm2), less fullness (−549 mm2), more desire to eat (+634 mm2) and ability to eat much more (+713 mm2) while on PS when compared to CS, but these differences were not statistically different from 0 (all p > 0.20).ConclusionThe effects of mandatory consumption of egg protein on energy balance in a free‐living setting do not differ from the effects of mandatory consumption of maltodextrin over a 5‐day period. This study does not support that eating high‐protein foods in this context would have a beneficial effect on energy balance, when compared to consuming high carbohydrate foods.Support or Funding InformationThis work was funded by the Egg Nutrition Center.