WHAT IS OBESITY? 

Stable weight depends on an even balance between energy intake from food and energy expenditure. Energy expenditure occurs during the day in three ways: 

As energy expended during rest ( basal metabolism ). This accounts for about two-thirds of expended energy, which is generally used to maintain body functions, such as maintaining body temperature and muscle contractions in the heart and intestine. 

As energy used to metabolize food ( thermogenesis), accounting for about 10% of expended energy. 

As energy expended during physical activity.
When a person’s caloric intake exceeds his or her energy expenditure, the body stores the extra calories in the fat cells present in adipose tissue. These adipose cells function as energy reservoirs, and they enlarge or contract depending on how people use this energy. If people do not balance energy input and output by adopting healthy eating habits and regular exercise, then fat builds up, and they may become overweight.
Measurement of Obesity 

Obesity is determined by measurement of body fat, not merely body weight. People might be over the weight limit for normal standards, but if they are very muscular with low body fat, they are not obese. Others might be normal or underweight, but still have excessive body fat. Different measurements and factors are used to determine whether or not a person is overweight to the degree that it threatens health:
Body mass index (BMI) (a measure of body fat). 

Waist circumference. 

Waist-hip ratio. 

Anthropometry. 

The presence or absence of other disease risk factors (eg, smoking, high blood pressure, unhealthy cholesterol levels, diabetes, relatives with heart disease) in addition to obesity. (Such risk factors plus BMI may be the most important components in determining health risks with weight.) 

 

 

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