Both westernization of diet and lifestyle habits and chronic inactivity have accelerated the obese population in Japan. Obesity is defined as being a condition in which the excessive energy is stored in the body as fat. Irrespective of organs and tissues, excessive fat accumulation impairs their structure and function, that is, ectopic adiposis. These days, the rapid increase in the number of adult people with abnormal liver function associated with obesity is largely attributed to an increase in the incidence of non-alcoholic fatty liver disease (NAFLD), a chronic liver disease accompanying fat accumulation. In Japan, about 30% of obese people suffer from NAFLD. About 10% of NAFLD progresses to non-alcoholic steatohepatitis (NASH). NASH is a progressive disease leading to liver cirrhosis. Any treatment with consensus other than diet restriction and exercise training is ineffective for the prevention of onset and progression of NAFLD. The important thing is a practice of suitable amounts of exercise, since it maintains muscle volume, increases the utilization of glucose, and attenuates insulin resistance, all of which may contribute to a decease in hepatic fat accumulation levels. It may be of great significance to practice exercise training for patients with chronic liver disease for improving the liver pathophysiology of NAFLD. In this review, first, the onset mechanism for NAFLD in obese subjects is summarized; second, beneficial effects of exercise on liver pathophysiology of NAFLD are reviewed based on the data from a weight reduction program consisting of dietary restriction plus aerobic exercise; and finally, medical support of obese patients with NAFLD in Tsukuba University Hospital are introduced.

Enrolled in our study were 16 seriously handicapped persons (9 males and 7 females) institutionalized in our medical center. They were 20 to 58 years of age (mean 35 yrs). In the previous study, we found they had no evidence, serological or clinical, of osteomalacia but were verified as having significantly low bone mineral density (BMD) at the calcaneus and lumbar vertebrae. Serum levels of 25-OH-vitamin D were low and positively correlated with the lumbar vertebral BMD. Thus we postulated that low BMD was at least partly due to the lack of ultraviolet exposure. In the present study, the lumbar vertebral BMD of the above subjects were measured before and after increasing their exposure to sunlight. We found that mean lumbar BMD increased signigicantly from 770 mg/cm² to 786 mg/cm² (P<0.05, Wilcoxon, paired test). The Z-score also increased significantlyfrom 78 ± 13% to 80 ± 12%(P<0.05, Wilcoxon, paired test).
These findings suggest low BMD could be corrected to some extent by increasing sunlight exposure of institutionalized persons. Former members of farming communities who are retired, handicapped, or otherwise limited to indoor activity, can also recover their BMD and prevent osteoporosis by an increased daily exposure to sunlight.