Body weight reduction by exercise increases the urinary 3-methylhistidine excretion level with relatively positive nitrogen, sodium, and potassium balances when compared to dietary restriction.

Background: Regarding changes in muscle mass, differences due to types of exercise and/or nutritional interventions, and associations with nutrient balances are still unclear. Methods: To estimate changes in muscle mass during a body weight loss program using either a diet or exercise regimen, we investigated levels of muscle mass-related indices, and body contents of nitrogen, sodium, and potassium as measured by the balance method. Six healthy young adult male volunteers participated in two 10-day crossover experiments (20 days total). The first 5 days comprised an adjustment period (energy intake, 2656 ± 367 kcal/day (mean ± standard deviation)). During the second 5-day period, the participants either reduced their energy intake to 1770 ± 244 kcal/day (diet regimen) or exercised on a bicycle ergometer to expend 886 ± 122 kcal/day (exercise regimen). Results: The nitrogen, sodium, and potassium balances were significantly more positive during the exercise regimen than during the diet regimen. The urinary excretion levels of creatinine, 3-methylhistidine (3-MH), aldosterone, and catecholamines, and the 3-MH/creatinine ratio were significantly increased only during the exercise regimen. Conclusions: The exercise regimen suppresses the decrease in muscle mass-related indices during body weight loss compared to the diet regimen with a relatively positive state of whole-body protein, sodium, and potassium balances, accompanied by an increase in sympathetic/adrenal cortical functions.

Remnant lipoprotein metabolism is improved more when body weight is reduced by exercise than by dietary restriction.

BACKGROUND: Remnant lipoprotein levels during weight-loss programs have not been examined in detail. We investigated the effects of reducing body weight by exercise and by dietary restriction on lipid metabolism including remnant-like particle-cholesterol (RLP-C) and apolipoprotein B48 (apo B48). METHODS: Six adult male volunteers participated in 2 experiments over 10 days. The first 5 days were an adjustment period (energy intake, 2656+/-150 kcal/day; mean+/-SEM). During the second 5 days, the participants either exercised on a bicycle ergometer to consume 886+/-50 kcal/day or reduced their energy intake to 1770+/-100 kcal/day. RESULTS: Serum triglyceride (TG) and RLP-C levels were significantly lower, whereas the increase in high density lipoprotein-cholesterol (HDL-C) level was significantly larger after exercise than after dietary restriction. We measured changes (Delta) in serum levels and identified positive correlations between Delta insulin and Delta TG, Delta apo B48 (p<0.05) and Delta RLP-C (p=0.050) only during exercise. CONCLUSIONS: Reducing body weight by exercise has more beneficial effects on lipid metabolism than a dietary approach, and improved insulin resistance accompanies the decrease of serum remnant lipoprotein levels.

A simplified modification of the AOAC official method for determination of total dietary fiber using newly developed enzymes: preliminary interlaboratory study.

A preliminary interlaboratory study was conducted to evaluate the validity of the modified AOAC method for determination of total dietary fiber by Tada and Innami, in which the 3-step enzymatic digestion process in AOAC Method 991.43 is modified to a 2-step process without pH adjustment. Total dietary fiber contents in 8 representative foodstuffs were measured using both the original AOAC Method 991.43 and the modified method in 6 research facilities in Japan. Repeatability relative standard deviations, reproducibility relative standard deviations, and Horwitz ratio values from the modified method were equivalent to those from AOAC Method 991.43, except in the rice sample. However, this exceptional case shown in the modified method was entirely dissolved by the addition of alpha-amylase stabilizing agents. The modified method, which shortens the process of enzymatic digestion from 3 to 2 steps and in which only reaction temperature is adjusted under the same pH, was found not only to give accurate values comparable to the original method, but also to substantially reduce the labor required by the laboratory staff in the process of routine analysis. This study revealed that the validity of the modified method was further ensured by adding alpha-amylase stabilizing agents to the reaction system.