The disappearance rate of an injected depot of radioactive Xenon dissolved in saline has been used to measure the blood flow through human adipose tissue according to the tissue clearance principle of Kety. The technical details regarding the injection and radioactivity measurement are described and the theoretical implications of the use of local clearance methods in general are discussed. The study comprised 69 examinations of 17 men and 38 women in various states of nutrition. The average blood flow, as measured in the abdominal fatty tissue, was 2.6 ml/100 g. min with a standard deviation of 1.7, and it was found to decrease significantly with increasing thickness of the fatty tissue.

A significant relationship between body weight (BW) and bone mass (BM) has been established previously. A diet-induced weight loss is accompanied by a significant decrease in bone mineral density (BMD) and total body bone mineral (TBBM), but the underlying mechanisms are not clarified. Sixty-two obese women were included in the study. Dual-energy X-ray absorptiometry (DXA) and measurements of a series of calciumregulating hormones and biochemical markers of bone turnover were performed at baseline and after 1 month and 3 months on a low calorie diet. Thirty of the women were randomized to a daily supplement of 1 g of calcium. After an additional 3 months without dietary prescriptions or calcium supplements, a subgroup of 48 subjects (24 from each group) were scanned again using DXA. There was a significant decrease in TBBM after 1 month and 3 months. A similar pattern was observed in the bone mineral content (BMC) of the lumbar spine in the patients who did not receive a calcium supplement, whereas no changes occurred in the supplemented group. The initial calcium supplementation seemed to protect against bone loss in the lumbar spine but not in the TBBM. In the nonsupplemented group, a statistically significant inverse correlation was found between the calcium/creatinine ratio in the morning urine and the changes in BMC of the lumbar spine. Such a relationship was not seen in the calcium-supplemented group. In the nonsupplemented group, no significant biochemical changes were observed, whereas a significant decrease in serum parathyroid hormone (PTH) was seen in the calcium-supplemented group. This might explain some of the protective effects of calcium supplementation on trabecular bone mass. We conclude that a diet-induced weight loss is accompanied by a generalized bone loss, which probably is explained mainly by a reduced mechanical strain on the skeleton. This loss can be partly inhibited by a high calcium intake. Therefore, a calcium supplementation should be recommended during weight loss, even if the diet contains the officially recommended amounts of calcium.

No abstract

We compared the weight-reducing effect of diet and gastroplasty with that of diet alone in a randomized trial in 60 morbidly obese patients followed for two years. Initial median body weight was 120 kg in patients randomly assigned to gastroplasty plus diet and 115 kg in those assigned to diet alone. Maximum weight losses did not differ significantly between the groups (26.1 kg in the gastroplasty group and 22.0 kg in the group treated with diet alone, P greater than 0.05). The risk of a Type II error with a true difference larger than 9.5 kg was less than 5 per cent. However, the group treated with diet alone regained significantly more weight after maximum weight loss had been achieved, so that the gastroplasty group had a more favorable net outcome at two years (P less than 0.05).