Article Abstract:
In the treatment of obesity, a therapy that would build or maintain muscle tissue while promoting the loss of fat tissue would be highly desirable. Growth hormone (GH) injections are being evaluated for this purpose. Obese subjects have participated in several studies in which various doses of GH have been combined with different levels of calorie restriction. In these studies, injections of GH, given every other day, caused increased retention of nitrogen, which indicates retention of proteins in the form of lean (muscle) tissue. It was concluded that GH increased nitrogen retention by way of a mediator known as insulin-like growth factor I (IGF-I), which was increased in the blood. However, the effects of GH on nitrogen retention and IGF-I were diminished when the subjects were put on a strict low-calorie diet. In the current study, eight obese women followed the same strict diet, but were given twice the dose of growth hormone to determine whether this combination would facilitate loss of fat and maintenance of muscle mass. The women, who were 33 to 83 percent over their ideal body weight for height, followed the regimen for 14 weeks. During the study period, each woman was given GH injections for five weeks and placebo (inactive) injections for another five weeks. The results demonstrated that GH had no significant effect on loss of body fat, but it did cause significant increases in plasma IGF-I, indicative of gains in muscle mass. Because the effect of GH seems to be dose-dependent, these findings may be applicable to treating patients with diseases involving the deterioration of muscle tissue. (Consumer Summary produced by Reliance Medical Information, Inc.)
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Article Abstract:
The safety of very-low-calorie diets (VLCDs) has been questioned; 60 deaths were associated with these diets in the 1970s. The diets typically contained collagen, a poor-quality protein, and inadequate amounts of vitamins and minerals; in some cases, there was no doctor supervision. Many of the people who died while following VLCDs had chronic diseases that may have contributed to their deaths. One report documents 17 persons who died while on VLCDs who had no known predisposing medical condition; electrocardiogram (ECG) results of some of these individuals indicated cardiac arrhythmias, or abnormalities in heart rhythm. A study was performed with 24 obese women who followed a VLCD (660 to 720 calories per day) for six weeks. The safety of this diet was evaluated by giving the subjects stress tests; these tests can induce cardiac arrythmia in patients who are susceptible. Cardiac tests were performed before, during, and after the six weeks of dieting; no abnormal changes in ECG readings were noted. These results support the assumption that VLCDs are safe for use by normal, healthy overweight women under the study conditions. The study diet supplied over 650 calories per day, included adequate amounts of vitamins, minerals, and high-quality protein, and subjects were monitored for six weeks. A VLCD supplying fewer calories or less nutritional quality may not be as safe. (Consumer Summary produced by Reliance Medical Information, Inc.)
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Article Abstract:
The effects of aerobic exercise training and weight loss on blood lipids were assessed in 21 mildly obese women, who were placed on a stringent lactovegetarian diet, consisting of 1,268 kilocalories for five weeks. The subjects were divided into exercise and non-exercise groups. Exercise consisted of walking at 60 percent of the heart-rate reserve (134 beats per minute) for 45 minutes five times a week. Although exercise improved oxygen consumption, changes in total body, lean body, and fat weight were similar for both groups. Total body weight decreased 5.5 kilograms (kg) in exercising women and 5.6 kg in nonexercising women. The pattern of change for high-density-lipoprotein cholesterol (HDL-C) differed between the two groups, but changes in total cholesterol (TC), low-density-lipoprotein cholesterol (LDL-C), triglycerides, and glucose were similar for all subjects. The 12.7 percent decrease in TC resulted from a change in the quality of the diet and body weight. When diet and body weight are similar for exercising and non-exercising mildly obese women, moderate exercise training improved only HDL-C. (Consumer Summary produced by Reliance Medical Information, Inc.)
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