Satiating Effect Of High Protein Diets On Resistance-trained Individuals In Energy Deficit.

Abstract

Short-term energy deficit strategies are practiced by weight class and physique athletes, often involving high protein intakes to maximize satiety and maintain lean mass despite a paucity of research. This study compared the satiating effect of two protein diets on resistance-trained individuals during short-term energy deficit. Following ethical approval, 16 participants (age: 28 ± 2 years; height: 1.72 ± 0.03 m; body-mass: 88.83 ± 5.54 kg; body-fat: 21.85 ± 1.82%) were randomly assigned to 7-days moderate (PRO MOD : 1.8 g•kg −1 •d −1 ) or high protein (PRO HIGH : 2.9 g•kg −1 •d −1 ) matched calorie-deficit diets in a cross-over design. Daily satiety responses were recorded throughout interventions. Pre-post diet, plasma ghrelin and peptide tyrosine tyrosine (PYY), and satiety ratings were assessed in response to a protein-rich meal. Only perceived satisfaction was significantly greater following PRO HIGH (67.29 ± 4.28 v 58.96 ± 4.51 mm, p = 0.04). Perceived cravings increased following PRO MOD only (46.25 ± 4.96 to 57.60 ± 4.41 mm, p = 0.01). Absolute ghrelin concentration significantly reduced post-meal following PRO MOD (972.8 ± 130.4 to 613.6 ± 114.3 pg•mL −1 ; p = 0.003), remaining lower than PRO HIGH at 2 h (−0.40 ± 0.06 v −0.26 ± 0.06 pg•mL −1 normalized relative change; p = 0.015). Absolute PYY concentration increased to a similar extent post-meal (PRO MOD : 84.9 ± 8.9 to 147.1 ± 11.9 pg•mL −1 , PRO HIGH : 100.6 ± 9.5 to 143.3 ± 12.0 pg•mL −1 ; p < 0.001), but expressed as relative change difference was significantly greater for PRO MOD at 2 h (+0.39 ± 0.20 pg•mL −1 v −0.28 ± 0.12 pg•mL −1 ; p = 0.001). Perceived hunger, fullness and satisfaction post-meal were comparable between diets (p > 0.05). However, desire to eat remained significantly blunted for PRO MOD (p = 0.048). PRO HIGH does not confer additional satiating benefits in resistance-trained individuals during short-term energy deficit. Ghrelin and PYY responses to a test-meal support the contention that satiety was maintained following PRO MOD , although athletes experiencing negative symptoms (i.e., cravings) may benefit from protein-rich meals as opposed to over-consumption of protein.

A systematic review of interventions targeting modifiable factors that impact dietary intake in athletes

“…Macronutrient contribution to total energy intakes are considered factors to be investigated due to the possibility that throughout the course of the intervention, this factor may impact overall energy intake due to gastric emptying variation ( 62 ) or changes in hormonal appetite response ( 63 ) . A macronutrient adjustment intervention was used to impact a variety of factors being investigated: hunger and appetite ( n 5) ( 56 , 57 , 59 – 61 ) and body composition ( n 2) ( 44 , 58 ) . Studies that included a macronutrient adjustment interventions used a variety of study designs, such as randomised crossover trial ( n 4) ( 44 , 58 , 59 , 61 ) , randomised double-blind trial ( n 1) ( 60 ) , counterbalanced trial ( n 1) ( 57 ) and randomised, double-blind, placebo-controlled trial ( n 1) ( 56 ) .…”

“…carbohydrate supplementation ( 60 ) . However, Roberts et al ( 61 ) identified significant differences between moderate-protein and high-protein diet groups in ad libitum buffet consumption, with an increase in protein intake and decrease in carbohydrate intake in the high-protein diet intervention group. No significant differences were found in total energy intake for three of the included studies ( 56 – 58 ) .…”

“…Dietary intake was measured using a wide variety of tools, such as direct observation (n 1) (56) , 24-h recall (n 1) (57) , 7-d food record (n 1) (58) , ad libitum buffet meal (n 3) (59)(60)(61) , electronic food record (n 1) (44) and diet record (n 1) (61) . Investigated factor outcomes were measured using a variety of tools, including visual analogue scale (VAS) for measuring appetite (n 4) (56,(59)(60)(61) , nutrition knowledge questionnaire for measuring nutrition knowledge (n 1) (58) , digital scales (n 2) (44,57) , DXA (n 1) (57) and BODPOD (n 1) (44) for measuring body composition. Total energy intake ad libitum meal was significantly lower for those who consumed carbohydrate supplements before the meal than those who did not (59) , as well as those consuming protein supplementation v. carbohydrate supplementation (60) .…”

“…Macronutrient adjustment interventions were used in seven of the included twenty-four studies. Macronutrient adjustment interventions involved changing intake of one or more macronutrients via supplementation (n 5) (56)(57)(58)(59)(60) or change in overall diet pattern (n 2) (44,61) . Macronutrient contribution to total energy intakes are considered factors to be investigated due to the possibility that throughout the course of the intervention, this factor may impact overall energy intake due to gastric emptying variation (62) or changes in hormonal appetite response (63) .…”

“…A macronutrient adjustment intervention was used to impact a variety of factors being investigated: hunger and appetite (n 5) (56,57,(59)(60)(61) and body composition (n 2) (44,58) . Studies that included a macronutrient adjustment interventions used a variety of study designs, such as randomised crossover trial (n 4) (44,58,59,61) , randomised double-blind trial (n 1) (60) , counterbalanced trial (n 1) (57) and randomised, double-blind, placebo-controlled trial (n 1) (56) . Dietary intake was measured using a wide variety of tools, such as direct observation (n 1) (56) , 24-h recall (n 1) (57) , 7-d food record (n 1) (58) , ad libitum buffet meal (n 3) (59)(60)(61) , electronic food record (n 1) (44) and diet record (n 1) (61) .…”