Obesity and Exercise

By Dr Ananya Mandal, MD

Obesity usually means an imbalance between energy intake and expenditure such that the excess energy is stored in fat cells. These fat cells increase in number leading to several health consequences.

Excess body fat frequently results in increased risk of heart disease, diabetes, gallbladder and liver disease, arthritis and some cancers. Obesity has become a global epidemic with an estimated 1.3 billion people overweight or obese.

Causes of obesity

Among the risk factors of obesity, the prominent ones include increased intake of energy rich foods and decreased physical activity or sedentary lifestyle.

Other causes of obesity include endocrine, hypothalamic and genetic disorders. There is a fine balance between calorie intake and expenditure that gets negatively affected by lifestyle factors such as excess dietary fat, sugar and decreased physical activity. This leads to negative alterations in the body’s physiology.

BMI

Individuals are considered obese when they weigh more than 20% above their ideal weight. Body mass index (BMI) is calculated as weight in kilograms divided by height in meters squared.

The currently accepted criteria for overweight is defined as body mass index (BMI) levels greater than 25 kg/m2 and obesity as BMI of 30 kg/m2. Another measure is the percentages of body fat as shown here:-

  Men Women
Minimal Fat 5% 8%
Below Average 5-15% 14-23%
Above Average 16-25% 24-32%
At Risk >25% >32%

Distribution of fat

The distribution of fat is one of the major contributors to disease. For example upper body fat distribution is termed Android and has been associated with increased risk of coronary artery disease, high blood pressure, high cholesterol levels, diabetes as well as hormone and menstrual dysfunction. It is determined by measurement of waist – to – hip ratio.

  Men Women
Lower fat distribution (low-risk) < 0.78 < 0.78
Upper body fat distribution (high-risk) > 0.91 > 0.86

Risk of disease through fat distribution can also be measured by the waist circumference measurement, measured in centimetres:

  Men Women
Low-risk < /= 102cm < /= 88cm
High-risk > 102 cm > 88cm

Exercise and managing obesity

Exercise thus is one of the most important measures in managing obesity. It is commonly added to diet alterations, medications and surgical management of obesity.

Apart from reducing weight by increasing calorie consumption, exercise also improves self esteem that in turn increases adherence to both diet and physical activity.

Exercise therapy for obesity needs to develop in a planned and monitored program of activities that would suit the needs of the patient best. Exercise should begin slowly and should be increase as functional capacity improves.

Exercise and body fat distribution

Exercise reduces body weight and affects body fat distribution by promoting regional fat loss especially at the abdomen. This reduces the risk of the diseases associated with upper body fat distribution. In addition the lost weight is also maintained best with exercise.

Exercise and glucose metabolism

In addition to weight reduction, exercise improves glucose metabolism and reduces fasting blood glucose, fating blood insulin levels, improves glucose tolerance and decreases insulin resistance.

However it needs to be remembered cessation of exercise can lead to significant increases in intra-abdominal fat within weeks or months according to some studies.

Reviewed by , BA Hons (Cantab)

Further Reading

Last Updated: Apr 8, 2013

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