Effect of Different Isoenergetic Breakfast Compositions on Blood Glucose Regulation, Energy Allocation and Satiety

Background and purpose: The increasing prevalence of overweight and obesity among adults, demands improved dietary strategies for weight management and metabolic competence. Hence, the objective of this study was to assess the short-term effects of breakfasts with varying macronutrient composition on blood glucose regulation, energy metabolism and satiety. Methods: This study examined ten healthy males (25.6 ± 4.4 yrs; BMI 23.2 ± 0.9 kg/m²) fed isoenergetic breakfasts rich in either Carbohydrate (CH) (68% of energy), Fat (Fat) (64% of energy) or Protein (P) (35% of energy) or a breakfast which reflected the individuals Normal (N) breakfast composition. Blood glucose and lactate, resting oxygen consumption (VO 2 ), Respiratory Quotient (RQ) and satiety feeling were measured. All breakfasts with the exception of the individual normal breakfast variant were isoenergetic and all contained the same amount of dietary fiber. As a non-dietary control, subjects drank 200 ml water on one test day, with the same metabolic parameters measured. Results: Compared with the water control day, there was a significant macronutrient-induced change in the metabolic parameters. The most significant increases in blood glucose were found after the Carbohydrate breakfast and the individual normal breakfast, whereas the Fat and Protein-rich breakfasts induced comparatively smaller blood glucose responses. Only the Protein- rich breakfast led to significant increases in resting VO2 (up to 30%) without changes in RQ. Finally, the Protein-rich breakfast induced the highest satiety feeling. Conclusions: Although the Protein-induced effects may initially appear minor, the combination of a reduced glycemic response, increased VO 2 , a proportionately high fat oxidation and a stronger satiety effect may support the use of this dietary approach for healthy weight management in normal weight men.