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 dietary strategies have been shown to support weight reduction and improve body composition during lifestyle interventions. However, evidence regarding long-term dietary adaptations and their association with body composition in overweight women remains limited. This secondary analysis of the ACOORH randomised controlled trial investigated whether a protein-rich soy-based meal replacement promotes sustained dietary protein intake and favourable body composition changes in female participants. Methods: Female participants from the multicentre ACOORH RCT with complete dietary records at baseline, week 12 and week 52 were included (n = 64). Participants received either a standardised lifestyle intervention alone or the same intervention combined with a protein-rich soy–yoghurt–honey meal replacement during the first 26 weeks. Dietary intake, body composition, physical activity and muscle strength were evaluated longitudinally. Between-group comparisons, repeated measures ANCOVA and exploratory correlation analyses were performed. Results: Both groups significantly reduced daily energy intake during the first 12 weeks. However, only the intervention group increased body weight-adjusted protein intake (+0.22 ± 0.29 g/kg/day), resulting in a significant between-group difference (p = 0.004). The higher protein intake was maintained throughout the 52-week study despite discontinuation of meal replacement after week 26 (p < 0.001). Repeated measures ANCOVA demonstrated significantly greater improvements in body mass index (p = 0.04) and fat mass (p = 0.03) in the intervention group. At week 52, higher protein intake was significantly associated with lower body mass index (r = −0.253; p = 0.04), lower fat mass (r = −0.321; p = 0.01) and greater muscle strength (r = 0.292; p = 0.02), whereas no association with physical activity was observed. Conclusions: Among overweight women participating in a structured lifestyle intervention, temporary supplementation with a protein-rich soy-based meal replacement was associated with sustained increases in dietary protein intake and more favourable long-term body composition. These findings support the concept that maintaining a higher protein intake during weight reduction may contribute to improved body composition outcomes. Larger prospective studies specifically designed to investigate sex-specific effects of protein-rich dietary interventions are warranted.