The role of physical exercise in weight loss programs

A successful long-term weight loss program consists of diet, physical activity, and behavior modification. For decades, regular exercise has been recognized a cornerstone of weight management, along with diet and medication. In fact, in addition to its important role in weight management for obese and diabetic patients, there is irrefutable evidence of the effectiveness of regular exercising in the treatment and prevention of other chronic diseases such as cardiovascular disorders, cancer, high blood pressure, depression and osteoporosis. Unhealthy lifestyles, such as lack of physical exercise and inappropriate dieting, initiate and propagate the weight gaining due to the unbalanced food intake and energy expenditure. Physical activity is a core part of lifestyle modification that can prevent people from obesity or type 2 diabetes.

Obesity/overweight is an extremely prevalent problem that is associated with a range of potential health risks. Exercise intervention has long been included various weight loss programs by health care professionals in an effort to combat the rising prevalence of obesity. Although dieting is important in the initial stage of weight loss, incorporating physical exercise as part of a weight loss plan helps maintain weight loss and prevent weight recycling syndrome in the long term. Exercise has been confirmed to be beneficial for weight loss as well as glycemic control in people with type 2 diabetes. Regular physical activity may improve insulin action through changes in regional adipose tissue (specialized connective tissue used as the major storage site for fat in the form of triglycerides) deposition which a recognized indicator of risk for type 2 diabetes and cardiovascular disease, and more recent researches suggest that intramuscular lipid is an preliminary contributor to the pathogenesis of insulin resistance.

As the most variable part of energy expenditure, regular physical exercise can help control the development of obesity and contribute to success in getting both short and long term weight loss. In people with obesity, exercise may be predominantly essential in sustaining initial weight loss via increasing total energy expenditure, preserving lean body mass, and producing modifications in substrate utilization. More over, the psychological benefits derived from regular participation in a physical program may serve as an additional driving force for engaging in such activities over the long run.

Either resistance or aerobic training alone may improve glycemic control and achieve weight loss in type 2 diabetes, but the improvements are most remarkable with combined aerobic and resistance training. Structured aerobic training (brisk walking, jogging, or cycling) or resistance training (weightlifting) decreased the absolute hemoglobin A1c (glycosylated hemoglobin) value by about 0.6%. The hemoglobin A1c value manifests the mean plasma glucose concentration over the previous two to three months. Higher levels of HbA1c can be found in patients with constantly elevated blood sugar, as in diabetes mellitus. Persistent elevations in HbA1c magnify the risk factors for vascular complications of diabetes such as heart attack, coronary disease, stroke, kidney failure, heart failure, erectile dysfunction, neuropathy, gangrene, and gastroparesis. These researches indicate that physical activity should be a mainstay of weight control and primary prevention of diabetes.

Resistance exercise may stimulate beneficial changes in insulin sensitivity through muscle mass development, promoting glucose clearance from the circulation, effectively raising glucose storage, and decreasing the quantity of insulin necessary for the maintenance of a normal glucose tolerance. Because of the health benefits from resistance exercising, experts recommend that resistance training be included in various fitness programs, in particular, weight loss programs. People with type 2 diabetes are recommended to perform resistance training three times a week.

However, physical activity alone, without concomitant diet control and lifestyle modification, is not sufficient to produce remarkable weight loss. Because obese patient often have trouble performing sufficient exercise to create enough energy expenditure. Moreover, for people of this group it is very possible to counterbalance increased energy consumption through physical training by more food intake or becoming inactive when not participating in the exercise programs. Besides, there is controversy over whether aerobic and/or resistance exercise has the same effect on weight loss as compared with dietary caloric restriction.