The aim of this study was to compare the impact of a high-protein meal replacement (HP-MR) versus a control (CON) breakfast on exercise metabolism. In this acute, randomized controlled, cross-over study, participants were allocated into two isocaloric arms: (a) HP-MR: 30% carbohydrate, 43% protein, and 27% fat; (b) CON: 55% carbohydrate, 15% protein, and 30% fat. Following breakfast, participants performed a moderate-intensity aerobic exercise while inside a whole-body calorimetry unit. Energy expenditure, macronutrient oxidation, appetite sensations, and metabolic blood markers were assessed. Forty-three healthy, normal-weight adults (24 males) participated. Compared to the CON breakfast, the HP-MR produced higher fat oxidation (1.07 ± 0.33 g/session; p = 0.003) and lower carbohydrate oxidation (−2.32 ± 0.98 g/session; p = 0.023) and respiratory exchange ratio (−0.01 ± 0.00; p = 0.003) during exercise. After exercise, increases in hunger were lower during the HP-MR condition. Changes in blood markers from the fasting state to post-exercise during the HP-MR condition were greater for insulin, low-density lipoprotein cholesterol, peptide tyrosine-tyrosine, and gluca-gon-like peptide 1, and lower for triglyceride and glycerol. Our primary findings were that a HP-MR produced higher fat oxidation during the exercise session, suppression of hunger, and improved metabolic profile after it.

Although meal replacement can lead to weight reduction, there is uncertainty whether this dietary approach implemented into a lifestyle programme can improve long-term dietary intake. In this subanalysis of the Almased Concept against Overweight and Obesity and Related Health Risk (ACOORH) study (n = 463), participants with metabolic risk factors were randomly assigned to either a meal replacement-based lifestyle intervention group (INT) or a lifestyle intervention control group (CON). This subanalysis relies only on data of participants (n = 119) who returned correctly completed dietary records at baseline, and after 12 and 52 weeks. Both groups were not matched for nutrient composition at baseline. These data were further stratified by sex and also associated with weight change. INT showed a higher increase in protein intake related to the daily energy intake after 12 weeks (+6.37% [4.69; 8.04] vs. +2.48% [0.73; 4.23], p < 0.001) of intervention compared to CON. Fat and carbohydrate intake related to the daily energy intake were more strongly reduced in the INT compared to CON (both p < 0.01). After sex stratification, particularly INT-women increased their total protein intake after 12 (INT: +12.7 g vs. CON: −5.1 g, p = 0.021) and 52 weeks (INT: +5.7 g vs. CON: −16.4 g, p = 0.002) compared to CON. Protein intake was negatively associated with weight change (r = −0.421; p < 0.001) after 12 weeks. The results indicate that a protein-rich dietary strategy with a meal replacement can improve long-term nutritional intake, and was associated with weight loss.

Background: High-protein diets and total diet replacements are becoming increasingly popular for weight regulation; however, further research is needed to elucidate their impact on the physiology of body weight regulation. The aim of this inpatient metabolic balance study is to compare the impact of a high-protein total diet replacement versus a control diet (North American) on energy expenditure, macronutrient oxidation rates and balances, metabolic blood markers and appetite sensations in healthy adults. Methods: Two randomized, controlled, cross-over clinical trials conducted separately in men and women will be conducted. In each trial, participants will be allocated to two isocaloric arms: a) Control diet: 55% carbohydrate, 15% protein, and 30% fat; b) High-protein total diet replacement: 35% of carbohydrate, 40% protein, and 25% fat. They will receive the prescribed diets for 32 h while inside the whole-body calorimetry unit. Diets will be designed to ensure participants are in energy balance. The following physiological changes will be compared between groups: energy expenditure, macronutrient oxidation rates and balances, metabolic blood markers, and appetite sensations. Body composition will be assessed at baseline using dual-energy X-ray absorptiometry. Discussion: This will be the first inpatient metabolic balance study examining the impact of a high-protein total diet replacement on energy metabolism, metabolic blood markers and appetite sensations in healthy young adults (of both sexes) using a whole-body calorimetry unit. Results of this clinical trial can ultimately be used to develop strategies to optimize high-protein diet interventions and weight management. Trial registration: ClinicalTrials.gov Identifiers: NCT02811276 (registered on 16 June 2016) and NCT03565510 (registered on 11 June 2018). Protocol version: NCT02811276: version 10 (2 March 2018); NCT03565510: version 3 (28 September 2018).

The aim of this study was to characterize the metabolic profile of healthy, normal-weight adults presenting with low satiety responsiveness. Individuals were categorized with low or high satiety responsiveness (LSR and HSR, respectively) based on the satiety quotient (SQ), a marker of satiety responsiveness, which was calculated following two isocaloric breakfast test meals offered while participants were inside the whole-room indirect calorimeter (WRIC): 1) North American: 55 % carbohydrate, 15 % protein, and 30 % fat; 2) High-protein: 31 % carbohydrate, 43 % protein, and 26 % fat. Following the North American breakfast, participants continued receiving a diet resembling the North American dietary pattern while inside the WRIC for 32 consecutive hours where the following outcome measures were assessed: energy metabolism components, metabolic blood markers, and appetite sensations. Forty-three participants were included; 13 were classified as LSR (n = 3 females; n = 10 males), n = 16 as HSR (n = 10 females; n = 6 males), and n = 14 were uncategorized. Compared with HSR, individuals with LSR had higher body weight (5.4 ± 2.5 kg; P = 0.042) and waist circumference (LSR: 77.5 (7.6) cm; HSR: 70.7 (5.2) cm; P = 0.012). Participants with LSR presented with higher total energy expenditure (184 ± 85 kcal/day; P = 0.040) and carbohydrate oxidation rate (34 ± 13 g/day; P = 0.015). Moreover, individuals in the LSR category presented with weakened satiety response to the meals when compared to those with HSR. Our primary findings were that, compared to individuals with HSR, those in the LSR category exhibited differences in their metabolic profile. The long-term impact on body weight and overall health should be assessed in further studies.