Ghrelin, an endogenous ligand for the growth hormone (GH) secretagogue receptor, has been reported to induce a GH-releasing, orexigenic effect on weight gain, and adipogenic actions. It is, therefore, thought that ghrelin links the regulatory systems for growth and energy balance.We examined 25 obese children undergoing a 3-month inpatient weight reduction program for obese children based on a combination of diet and exercise therapy and evaluated the change in the serum ghrelin levels.The subjects consisted of 25 children with moderate to severe simple obesity [17 boys, 8 girls ; mean age 9.9±1.3 years, percent overweight (% overweight) 52.1±13.6%]. Height, weight, percent body fat (% BF), fat mass, fat-free mass (FFM), and serum ghrelin were measured before and after weight reduction.After therapy, body weight, % BF and fat mass had all significantly decreased (p<0.001), while height and FFM had both significantly increased (p<0.001 ; p<0.05, respectively). There were no correlations between pre-therapy serum ghrelin and any of the following: initial height, weight, % overweight, % BF, fat mass, or FFM. However, after therapy, serum ghrelin levels were negatively correlated with body weight (r_s=-0.544, p<0.01). Serum ghrelin levels increased significantly from pre- to post-therapy (113.9±30.7 to 129.6±42.9 fmol/ml, p<0.05). The rate of changes in ghrelin levels was negatively correlated with the rate of change in the % overweight (r_s=-0.412, p<0.05).These findings suggest that long-term weight reduction based on a combination of diet and exercise therapy lessens the severity of obesity and increases serum ghrelin levels in obese children.

The decrease in physical activity in elementary school children is an important problem in Japan. Previous studies have shown that physical activity during the summer vacation is lower than during the school days, and a program for increase in physical activity during the summer vacation are required. Therefore, the purpose of this study is to assess the effectiveness of physical education homework and exercise events during summer vacation in elementary school children. A total of 67 children in grade 4 were assigned to the two groups for each school: the control school (n = 39) or the intervention school (i.e., did physical education homework and participated in exercise events; n = 28). Physical education homework was constituted of four exercise programs per day. Additionally, exercise events were carried out four times during the summer vacation. Physical activity before and during the summer vacation were measured by accelerometer (Lifecorder EX). The decline in physical activity of the intervention school was less than the control school, and significant interactions were indicated by two-way repeated ANOVA (Step count: F (1, 65) = 6.704; Light-intensity physical activity, LPA: F (1, 65) = 4.365; Moderate- to vigorous-intensity physical activity, MVPA: F (1, 65) = 6.088, all P < 0.05, respectively). After adjusted for sex, percentage of overweight, participation of sport activity, and each physical activity, significant trends of interactions about the step count, LPA, and MVPA were shown (Step count: F (1, 61) = 3.982, P = 0.050; LPA: F (1, 61) = 3.243, P = 0.077; MVPA: F (1, 61) = 2.916, P = 0.093). These results suggest that combined use of physical education homework and exercise events are effective to attenuate the decrease in physical activity during summer vacation in elementary school children.