Relationship between Seasonal Changes in Food Intake and Energy Metabolism, Physical Activity, and Body Composition in Young Japanese Women.

We investigated seasonal changes in food intake, energy metabolism, and physical activity (PA) and explored their associations with body composition. In total, 28 women aged 20−23 years in the Kansai area of Japan participated in this year-long study spanning the winter, spring, and summer seasons. A dietary investigation was performed using the weight recording method, and the amount of histidine in the diet, which may be related to the regulation of energy intake, was calculated. Resting metabolic rate (RMR), body composition, and PA were measured using indirect calorimetry, bioelectrical impedance analysis, and uniaxial accelerometry, respectively. The results showed that energy intake was highest in winter, decreased significantly with increasing temperature, and decreased by 25% in summer. As the intake of histidine in the diet did not increase in summer, it did not seem to be involved in the suppression of energy intake. RMR was highest in winter and decreased significantly in summer by 20%. The amount of PA was low in winter, increased significantly in the spring, and decreased again in summer. Body weight increased in winter, with an accumulation of fat in the trunk and arms, and decreased in summer, with a reduction in the amount of fat. Greater energy intake and less PA in winter induced an increment in body weight despite the increase in RMR. There were no significant changes in lean body mass between the seasons; however, the muscle weight of the lower limbs increased significantly in spring and in summer compared with that in winter (p < 0.001). Thus, seasonal changes in food intake, energy metabolism, and PA occur, with resultant changes in the body composition under comfortable air-conditioned environments.

Excessive fat restriction might promote the recurrence of colorectal tumors.

The incidence of colorectal cancer is rapidly increasing in Japan. This trend has been suggested to be caused by an increasing fat intake as a result of the Westernized diet among Japanese. We investigated whether dietary instruction optimizing the fat energy ratio suppresses the recurrence of colorectal tumors. The subjects, 373 men and women, were the participants in a randomized clinical trial of colorectal cancer prophylaxis. At entry, each participant completed a 3-consecutive-day food record on which dietary instruction was given to restrict fat energy ratio to 18-22%. Data obtained before and after the intervention were examined by cohort analysis. The primary endpoint was the presence or absence of colorectal tumor(s) at colonoscopy after 4 yr. Unexpectedly, the recurrence of tumor increased as the subjects reduced their fat intake. The lowest tumor recurrence among the men was observed in the group with 23.8-26.4% fat energy ratio after the intervention. Furthermore, in men, the risk of tumors decreased significantly as the intake of linoleic acids per body weight increased. For women, similar trends were observed. These results suggest that extreme fat restriction is highly likely to promote the recurrence of colorectal tumors, which may be partly attributable to linoleic acid deficiency.

Metabolic response to short-term 4-day energy restriction in a controlled study.

OBJECTIVES: Metabolic rate is affected not solely by diet but also by environmental characteristics such as climate and seasonal changes in day length. In the present study, we conducted a controlled study in which we observed metabolic response to short-term energy restriction (ER). MATERIALS AND METHODS: Thirty-two subjects were divided randomly into a slight ER group and a moderate ER group. The energy intake per day for slight ER vs moderate ER was 1462 kcal vs 1114 kcal. During the 4-day study periods, the same daily timetable, which consists of nutrition, exercise, sleeping and others, was imposed on both groups. The same environment was also provided to both groups. RESULTS: After the 4-day ER, significant decreases in body weight and basal metabolic rate (BMR) were shown in both groups. The decrease in body weight was 2% of the baseline level in both groups, and the decreases in the BMR were 6% of baseline levels in the slight ER group and 13% in the moderate ER group. The decrease in BMR in the moderate ER group was significantly larger than that in the slight ER group. CONCLUSIONS: In a controlled study of short-term ER, we observed a significant decrease in BMR. There was a positive association between the degree of ER and the reduction in BMR. Reductions in BMR were greater than those in body weight. It, thus, appears that the minimization of weight loss is due to dramatic decreases in BMR. This suggests the existence of metabolic resistance against ER.