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.

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).

No abstract

Dual-energy x-ray absorptiometry was performed in 51 obese patients before and after 15 weeks on a low-calorie diet. Of these patients 39 were scanned 6 months later. Total and regional body bone mineral, fat mass, and fat free mass were measured. In the control group, 9 normal volunteers were scanned with up to 23 kg lard distributed anteriorly, and 9 volunteers were scanned with 15 kg lard posteriorly. The lard was then gradually removed to simulate the fat loss found in the patient group. In the patient group the mean weight loss was 12,273 g, the mean fat loss was 11,014 g, and the mean bone mineral loss was 171.6 g after 15 weeks. Close correlation between the fat loss and the bone loss was found and calculated to be 16.5 g bone mineral per kg fat in the patient group, in contrast with 0.5 g bone mineral per kg fat in the control group. In the control group, 15 kg lard placed posteriorly had no statistically significant effect on the bone measurements. If weight and fat were regained at the scanning time 6 months later, the bone mineral was regained as well. Patients with further weight loss continued to lose bone mineral. One patient lost 754 g bone mineral in 9 months. Her weight loss was 45 kg in that period, and the bone mineral content remained within the range for normal women at her age. Methodologic and pathogenetic problems are discussed. It is concluded that the observed bone loss should be regarded as physiologic normalization accompanying a diet-induced weight loss in the obese.

SummaryFive patients with gross obesity were subjected to an eleetrostimulatory exploration of the lateral hypothalamic area. In three eases a convincing hunger response was elicited. Two of these patients received unilateral electroeoagulatory lesions, and in the third a eontralateral (left sided) coagulation was performed three months later. In contrast to the two patients who had only been explored, the patients with lesions showed a statistieMly significant, but transient decrease from preoperative to postoperative spontaneous calorie intake.Body weight decreased slightly and temporarily, but was not significantly affected. It is concluded that in humans, as well as in experimental animals, the lateral hypothalamus is the site of nuclei or tracts that are related to hunger.

Thermogenic combinations of ephedrine with caffeine and newer selective beta 3-agonists are being assessed for the treatment of obesity. The actions of beta-agonists may be multifaceted, with acute stimulation of thermogenic mechanisms in various tissues. During chronic treatment recruitment of brown fat may occur and hypertrophy of skeletal muscle may occur and simultaneously increase lean body tissue and reduce fat mass by stimulation of lipolysis and energy expenditure. The weight-reducing effect of an ephedrine-caffeine combination was superior to placebo treatment during 24 wk of energy restriction in obese women, whereas caffeine and ephedrine separately had no effect. In a second study it was found that ephedrine-caffeine compared with placebo preserved fat-free mass and enhanced fat loss, which could be accounted for both by anorexia (75%) and by increased thermogenesis (25%). The ephedrine-caffeine compound seems useful for the treatment of obesity and may serve as reference in the clinical assessment of new beta-agonists.

For 2 years, 12 Danish hospitals have conducted a randomized clinical trial to evaluate the hazards and benefits of jejunoileal bypass operations for severe obesity. At present (January, 1976), there are 92 operated and 46 unoperated patients. There has been no mortality in the operated group. One control patient has died. Weight loss is significantly better in the operated group, but not always satisfactory. The well-known postoperative complications have not been deterring in frequency or seriousness. On the whole, but not invariably, the operation has been followed by an improvement in psychosocial status.