Daily dietary protein distribution does not influence changes in body composition during weight loss in women of reproductive years with overweight or obesity: a randomized controlled trial

Authors: DE LEON, ANGELA - FORMER ARS EMPLOYEE; Roemmich, James; Casperson, Shanon

Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/13/2024
Publication Date: 4/10/2024
Citation: De Leon, A., Roemmich, J.N., Casperson, S.L. 2024. Daily dietary protein distribution does not influence changes in body composition during weight loss in women of reproductive years with overweight or obesity: a randomized controlled trial. Journal of Nutrition. 154(4):1347-1355. https://doi.org/10.1016/j.tjnut.2024.02.009.
DOI: https://doi.org/10.1016/j.tjnut.2024.02.009

Interpretive Summary: Women, in particular, are are more likely to suffer with severe obesity (body mass index (BMI) = 40 kg/m2) and to experience a greater severity of obesity-related health problems. A common recommendation to produce weight loss is to eat a high-protein diet. But, these types of diets are difficult to maintain for any length of time. Consuming a more moderate amount of protein and distributing it evenly across all meals that has been shown to be beneficial maintaining skeletal muscle and may be more advantageous for women to help achieve and sustain better weight control. We found that the daily distribution of dietary protein did not produce differential alterations in body composition or weight loss. These results provide a better understanding about the protein needs of women during intentional weight loss.

Technical Abstract: Background: Preservation of fat-free mass (FFM) during intentional weight loss is challenging yet important to maintain resting metabolic rate, especially for women. A balanced protein distribution of 25-30g per meal improves 24-hour muscle protein synthesis which may promote FFM maintenance and greater reductions in fat mass (FM) during weight loss in women. Objective: We aimed to determine whether the daily dietary protein distribution pattern during energy restriction influences changes in body composition in women of reproductive years. We hypothesized that a balanced daily protein distribution compared to the usual intake pattern of consuming most of the protein at the dinner meal would be superior in preserving FFM while reducing FM during weight loss. Methods: Healthy women (n=43) aged 20-44y with a body mass index 28-45kg/m2 completed a randomized parallel feeding study testing two patterns of daily protein intake (even distribution across all meals vs. a skewed distribution with most protein consumed at the evening meal). Participants completed an 8-week controlled 20% energy restriction (all foods provided), followed by an 8-week self-choice phase in which participants were asked to maintain a similar diet and dietary pattern when purchasing and consuming their own foods. Body composition was measured at baseline, week 8, and week 16. Data were analyzed using linear mixed models. Statistical significance was set at P<0.05. Data are presented as differences in least squares means ± standard error. Results: No significant main effects of group or group by time interactions were observed. There were main effects of time for all measures (P<0.001). Overall, body weight, FFM, FM and body fat percentage decreased 5.6±0.4kg, 1.0±0.2kg, 4.6±0.4kg, and 2.3±0.2%, respectively, during this 16-week study. Conclusions: Daily dietary protein distribution at a fixed protein level does not appear to influence changes in body composition during weight loss in women of reproductive years.