Consuming 30 Grams of High-Quality Protein at Breakfast, Lunch, and Dinner Does Not Protect Against Loss of Fat-Free Mass During Weight Loss in Women

Abstract

Abstract Objectives Consuming 30 g of high-quality protein at each meal stimulates skeletal muscle protein synthesis more effectively than the typical intake pattern of consuming the majority of protein at dinner. We tested whether this dietary protein intake pattern protects against loss of skeletal muscle mass during weight loss. Methods Healthy overweight/obese women (age 31.1 ± 7.7 yrs.; BMI 35.6 ± 4.0 kg/m2) were provided with all foods for daily consumption at a level of 20% reduction of energy needs for 8 weeks. The diet provided 90 g of animal source protein daily with at least 30% of weekly protein requirements coming from beef. One group (EVEN; n = 18) received their animal source protein evenly distributed among breakfast, lunch, and dinner (30 g at each meal). The other group (SKEWED; n = 19) received their protein in a skewed distribution pattern with 10 g at breakfast (B), 15 g at lunch (L), and 65 g at dinner (D). Indirect calorimetry and Stanford Brief Activity Survey was used to assess energy intake. Diet History Questionnaire II was used to determine baseline protein intake. Body composition was determined via dual-energy X-ray absorptiometry pre- and post-intervention. Results Protein intake during the intervention was 23.0% ± 1.8% of calories, representing an increase of 7.1% ± 3.0% of calories compared to habitual diet. Weight loss was only marginally different between the groups (P = 0.076), with the EVEN group losing slightly more (5.3 ± 2.2 kg) body weight than the SKEWED group (4.2 ± 1.8 kg). Loss of fat mass did not differ (P = 0.650) between the EVEN (3.8 ± 1.9 kg) and SKEWED (3.7 ± 1.8 kg) groups. However, loss of fat-free mass was greater (P = 0.036) in the EVEN group (1.3 ± 0.8 kg) compared to the SKEWED group (0.8 ± 0.7 kg). Conclusions Contrary to our hypothesis, consuming 30 g of protein at breakfast, lunch, and dinner did not provide better protection against loss of fat-free mass during weight loss than consuming the majority of daily protein intake at a single meal. These preliminary results suggest that a meal protein intake of greater than 30 g is needed to spare metabolically active fat-free mass during energy restriction. Further research is needed to gain a better understanding of women's protein needs during weight loss. Funding Sources The United States Department of Agriculture and the North Dakota Beef Commission.