Overweight couch potatoes live a dangerous life: Epidemiologists estimate that about 80 percent of the most common diseases are linked to severe overweight and obesity and a sedentary lifestyle. Obese people are at an increased risk for cardiovascular diseases, vascular diseases, hypertension, diabetes and cancer. This lowers their life expectancy.
Weight loss and physical activity help to counteract this. Women who lose weight lower their breast cancer risk. Regular physical activity lowers the risk of developing breast, colorectal and cervical cancers.
The links between body weight, lifestyle and the risks of developing cancer and other chronic diseases are not yet understood in every detail. However, changes in hormonal signaling are believed to be among the culprits of these processes.
Fat tissue produces various hormones which have a big impact on metabolism. The important hormones are anti-inflammatory adiponectin, which increases the effect of insulin, and leptin, which can promote tumor cell growth.
Researchers from the National Center for Tumor Diseases (NCT) Heidelberg set out to determine if body weight and exercise also affect production of these key adipose tissue hormones? In a randomized controlled study with 439 overweight postmenopausal women, participants were divided into three intervention groups: 1) diet, 2) exercise, and 3) diet + exercise) as well as a control group.
The research team hypothesized that a combination of physical activity and weight loss should result in a more favorable relation of the two hormone levels.
Leptin production decreased in all three intervention groups, most noticeably (up to 40 percent) in the diet + exercise group. Adiponectin production increased most in women who were on a reduced calorie diet only.
Irrespective of the type of intervention, the positive effect on hormone production was dependent on the degree of weight loss: the more pounds a study participant had lost, the more her adiponectin levels increased and the more her leptin levels decreased. The greatest changes occurred in women who had lost ten percent of their initial body weight.
Leptin production appears to be influenced by changes of body composition, because in the exercise intervention group, participants gained muscle mass also without losing weight.
These study findings indicate the mechanisms by which weight loss and training protect from chronic diseases. The lead researcher said, "the health-promoting effect of adiponectin is regarded as established by numerous studies now. Lower leptin levels, on the other hand, offer less growth incentives for tumor cells. Therefore, we are now able to give well-founded recommendations to women how they can positively influence these two important metabolic regulators by keeping a healthy body weight and getting more exercise"
Journal of Internal Medicine, 2013.
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