Association of Protein Intake in Three Meals with Muscle Mass in Healthy Young Subjects: A Cross-Sectional Study.

Protein intake of >0.24 g/kg of body weight (BW) at a single meal is necessary to maximize muscle protein synthesis in a young population. However, the association between the protein intake rate for three meals and muscle mass in the young population has not been evaluated. We hypothesized that a protein intake of >0.24 g/kg BW at all three meals is effective for maintaining muscle mass. Therefore, we cross-sectionally examined the association between protein intake at all three meals with muscle mass in 266 healthy young subjects (aged 21.4 ± 2.4 years). Subjects were divided into the AP group, which achieved protein intake >0.24 g/kg BW at all three meals; and the NP group, which did not. We calculated total fat-free mass (FFM) and appendicular fat-free mass (AppFFM) with dual-energy X-ray absorptiometry, and the percentage of total FFM (TotalFFM%) and appendicular FFM (AppFFM%) were calculated as the percentage of BW (%BW). We demonstrated that TotalFFM% (77.0 ± 0.5 vs. 75.2 ± 0.4%, p = 0.008) and AppFFM% (34.7 ± 0.3 vs. 34.1 ± 0.2%, p = 0.058) were higher in the AP than in the NP group. This finding suggests that achieving protein intake of >0.24 g/kg BW at all three meals is important for muscle mass maintenance in young populations.

Skipping breakfast is associated with lower fat-free mass in healthy young subjects: a cross-sectional study.

Skipping breakfast has been reported to decrease daily energy and nutrient intake. We aimed to investigate whether habitual breakfast intake frequency is associated with fat-free mass (FFM) in healthy young subjects. We hypothesized that skipping breakfast and the subsequent negative energy balance may be risk factors for reduced muscle mass. This cross-sectional study included 270 healthy young subjects (152 men, 118 women). We collected information on habitual breakfast intake frequency, sleep quality according to the Pittsburgh Sleep Quality Index, circadian rhythm type using the Morningness-Eveningness Questionnaire, and physical activity using the International Physical Activity Questionnaire. According to the definition of National Health and Nutrition Examination Survey in Japan, the subjects were asked to report habitual breakfast intake frequency over the preceding month (excluding consumption of tablets, energy drinks, confectionary, fruits, dairy products, or sweetened beverages alone). FFM was assessed using dual-energy x-ray absorptiometry; then, appendicular FFM (AppFFM) was calculated. We also calculated appendicular skeletal muscle mass index (kg AppFFM/m2) and %AppFFM (% body weight) to adjust body size between individuals. Multiple regression analysis showed that habitual breakfast intake frequency was positively associated with appendicular skeletal muscle mass index (ß = .087, P = .031) and %AppFFM (ß = .086, P = .045) after adjusting for age, sex, living conditions, Pittsburgh Sleep Quality Index, Morningness-Eveningness Questionnaire, and International Physical Activity Questionnaire scores as covariates. These findings suggest that skipping breakfast is a risk factor for lower muscle mass in healthy young subjects, irrespective of strong confounders, such as age, sex, and physical activity.