Exercise and Obesity

The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.

Based on guidelines provided by the American College of Sports Medicine.

Condition Overview:

This condition is categorised by an increase in body fat levels. Obesity is a major risk factor for such chronic conditions as heart disease and type two diabetes. The distribution of body fat, rather than the amount of body fat is more indicative of disease risk. Upper body adiposity, specifically on the abdominal region is the greatest risk factor for these conditions.

Obesity can be caused by hormonal, genetic and thyroid disorders, though the major preventable risk factors are poor diet and insufficient physical activity. The relationship between diet and exercise creates a caloric balance. If energy consumed (diet) is greater than energy expended (physical activity), weight is gained. If the two variables are equal, weight remains the same. If Energy expenditure is greater than consumption, weight is lost.

Although this basic equation provides an overview of weight loss, maintenance or gain, there do exist a cascade of chemical and hormone factors resulting from this imbalance:

• Increased fasting insulin.
• Increased insulin response to exercise.
• Reduced insulin sensitivity.
• Decrease in growth hormone levels (thereby reducing lean muscle mass) and their response to insulin.
• Increased adrenocortical hormones.
• Increased cholesterol production.

The classification of obesity comes in several forms, including height/weight tables, body mass index (BMI), body fat percentage and waist to hip ratio.

Short Term Response to Exercise:

Directly, it is the increased body weight that provides the greatest effect on the ability to exercise. This reduces work capacity, and increases the energy expenditure required to complete a task. Indirectly, factors pertaining to heart disease, type two diabetes and hypertension will influence the ability to exercise.

Long Term Response to Exercise:

Along with nutritional modification, exercise and physical activity are vital in the treatment of obesity. It has been shown that in obese populations, exercise has a drastic effect on reducing upper body adiposity (in particular abdominal adiposity – the greatest predictor of chronic disease).

Exercise also has a considerable effect on insulin and glucose levels, thus aiding in the prevention and treatment of type two diabetes. These effects occur irrespective of any loss in weight, and include:

• Reduced blood glucose.
• Reduced insulin.
• Increased glucose tolerance.
• Reduced insulin resistance.

Condition Management:

The following techniques are employed in maximising the treatment of obesity.

• In terms of nutrition, consume five meals a day (three main meals and two snacks). Each meal/snack should include carbohydrates, protein and fat. 40% of your energy should come from carbohydrates and 30% each from protein and fat. A gram of carbohydrates contains 16kJ of energy, a gram of protein contains 17kJ of energy, and a gram of fat contains 37 kJ of energy. Lean protein from meat, fish, poultry, eggs, protein powder (though best to stick with whole foods where possible). Carbohydrates should come from vegies and fruit. Nothing that has been refined in any way. Choose low Glycaemic Index versions of these foods. Fat should be unsaturated.
• High intensity interval based exercise to maximise energy expenditure during exercise and to increase Excess Post-Exercise Oxygen consumption (‘passive’ energy expenditure for up to 38 hours following completion of a session).
• Short sessions to maximise quality and allow the required intensity.
• Resistance based exercise to maximise lean muscle mass and thus increase the size of the body’s metabolic engine. Every kilogram of muscle burns the equivalent of 6kg of fat per year.
• Efficient and complex full body compound movements to maximise the physical requirements of exercise.
• Alternating and conflicting movements to increase energy expenditure due to a blood shunting effect (redistribution of blood to different areas of the body, therefore maximising physical requirements).
• The moving of large loads, long distances, quickly, thus increasing work capacity and energy expenditure.
• Very high degree of variety to ensure constant adaptation.

Wallace, J. P., (2003). Obesity. In: Durstine, J. L., Moore, G. E. (2003), ACSM’s Exercise Management for Persons with Chronic Diseases and Disabilities 2nd Ed. (pp 149-156) American College of Sports Medicine, Human Kinetics