Overweight and obesity are both results of imbalances between calorie intake and expenditure. As the names would suggest, both are characterized by excess body weight (read fat).
BMI (basal metabolic rate) is the chief criterion used universally to classify an individual into normal weight, overweight or obese.
• BMI < 25 kg/m2: normal
• BMI > or = 25 kg/m2: overweight
• BMI > or = 30 kg/m2: obese
• BMI > or = 40 kg/m2: grossly obese
Although, BMI is accepted universally as the norm for determining overweight and obesity, it does not take into consideration the type of tissue. For example, a NFL player or a body builder weighing 320 lbs. and 5% body fat would be labelled obese using the BMI method.
Some therefore consider body fat % (skin fold thickness method) as a more accurate estimate. However, in the general population and for epidemiologic purposes, BMI is the preferred method. Height-weight charts, bio electrical impedance (BIA) are other methods used.
According to recent estimates, more than half of the human population can be safely said to be overweight, one third to be obese and 5% morbidly obese. According to Stein CJ and Colditz GA (The Epidemic of Obesity, J. Clin Endocrinol Metab., 2004), the health care costs related to the direct or indirect effects of obesity in the US alone are a staggering 117 billion dollars a year.
Android obesity: as the name suggest, this is mostly encountered in men. Fat deposition is chiefly around the abdomen with slender arms and legs.
Gynaecoid obesity: mostly seen in women; fat deposition mainly around the lower abdomen, hips and thighs with narrow shoulders, small breasts and waist.
Obesity associated with pathological states
Obesity can occur in relation to a number of diseases or disorders like Myxoedema, Hypothyroidism, Cushing's syndrome, metabolic syndrome, Polycystic ovarian disease, mood disorders and medications.
Complications of Obesity
• Weight gain
• Abdominal distension
• Cardiovascular disease
• Metabolic syndrome
• Appearance of striae (stretch marks)
• Menstruation disturbances
• Female infertility
• Carpal Tunnel Syndrome
For primary prevention as well as treatment of obesity and the more serious consequences of overweight and obesity, life style interventions are a crucial consideration. Reductions in energy intake along with increased energy expenditure are the key to losing weight. Energy can be expended by indulging in physical activity on most days of a week to a total 150 min per week. Moderate intensity (40-60% of VO2 max) will be essential to cause any sort of weight loss. Cardiorespiratory training in the form of jogging, cycling, an aerobics class or swimming should be prescribed. In addition, resistance training by its virtue of increasing muscle mass will increase basal metabolic rate and thus the basal expenditure of energy (muscles are the most metabolically active tissue, even at rest).
A weight loss of 5 to 10% will result in significant improvement in the risk of complications of obesity.