The aim of this randomized, controlled trial was to investigate effects of breakfast high or low in protein on body composition and cardiometabolic markers in young women with overweight. In total, 56 women aged 18-30 years consumed a breakfast containing either high-protein (HP, 34 g protein, n= 26) or low-protein (LP, 6 g protein, n=30) for 12 weeks. Measurements of body composition by DXA, waist circumference, glucose tolerance, and fasting glucose, insulin, and lipid profile were performed before and after this period. The primary outcome was fat mass. Satiety and hunger were evaluated by self-reported VAS-scores. Dietary intake was estimated by 4-day dietary records, and calcium intake was estimated by food frequency questionnaires. At baseline, relative daily protein intake was 15.2±2.8 E%, which increased to 19.3±3.4 E% in HP but was unchanged in LP (P<0.001 between groups). HP reported higher satiety compared to LP (P=0.02). Yet, no group differences were observed in changes in energy intake, body composition, blood lipid profile, or measures of glucose tolerance (all P>0.10). However, bone mineral content tended to increase in HP (P=0.05) and decrease in LP (P=0.07, interaction effect: P=0.01). Conclusively, a high versus low content of protein in breakfast increased satiety but did not affect body composition or cardiometabolic markers in young women with overweight. This study adds to the sparse evidence on effects of breakfast with different macro-nutrient compositions on health parameters in women with overweight. Registered at clinicaltrials.gov: NCT04518605.
Keywords: Obesity; dairy; diet intervention; fat mass; satiety.