Obesity is a major risk factor for the increasing rates of non-communicable diseases such as diabetes, heart diseases, and hypertension. The prevalence of these disorders is increasing not only in developed nations but also in developing countries such as India and China.
Obesity occurs when there is an imbalance between energy intake (food intake) and energy expenditure (physical activity). Therefore people who overeat, especially those who take calorie-rich food such as fats and sugar in large quantities, tend to gain weight.
A series of population surveys indicated that lifestyle changes in the urban and rural populations in southern India had produced marked increase in overweight and obesity. In the urban population, the percentage of obesity has increased from 23 per cent in 1995 to 41% in 2006. What is more striking is the change that has occurred in rural population in Southern India. From a very low rate of obesity of 2% in 1989 it has reached 20% in 2006. The socio-economic transition in rural areas has improved living conditions, transport facilities, food habits, medical care, educational status and family income. Sedentary habits like watching television have contributed to increasing rates of overweight and obesity associated metabolic diseases such as diabetes.
People who do not have much physical activity, either job-related or during leisure, accumulate large percentage of fat in the body; thereby weight gain is common in such persons. Indians tend to accumulate fat in the abdominal region or central obesity, which is a stronger risk factor than general weight gain. Walking, jogging, swimming and cycling are common forms of physical exercise. By losing excess weight or by maintaining ideal body weight, the risk of diseases like diabetes can be considerably reduced. There is sufficient scientific data to show that many metabolic diseases can be prevented by being physically active, losing excess weight and eating a healthy diet.
Paradigm shift
In recent years there has been a paradigm shift in the understanding of the mechanisms related to overweight and obesity. In the past decade it has been recognised that sedentary behaviour and physical inactivity are different constructs, which have independent effects in promoting many diseases. Scientists recognise that even a non-exercising activity that involves sitting or lying can be considered sedentary whereas any activity involving standing can be considered non-sedentary.
The modern world has several gadgets and devices by which human locomotion is minimised, physical exercise is reduced and sedentary behaviour is enhanced. Mechanisation at work has reduced the need for physical movement. Many studies have also shown that sitting time has increased in one's daily routine. Watching television, using computers, desk-bound occupation and commuting by automobiles have significantly reduced standing or walking time.
The modern environment promotes sedentary habits, which we will have to fight if we want to take charge of our health. The key points centre on quitting sedentary habits and obeso-genic food habits. The new sedentary behaviour paradigm is likely to create new avenues in research and interventions aimed at prevention and management of diseases like diabetes. Nearly 50-70 per cent of our waking day consists of sedentary behaviour. Non-sedentary behaviour involves standing activity or low grade ambulation. The energy expenditure associated with this is referred to as “non-exercise activity thermogenesis”. This consumes nearly 1.5-2.5 times more energy than the activities done during sitting, and thus helps to burn calories to a great extent. For example a waiter or nurse who stands and performs low grade ambulation at work spends large amount of energy in comparison with person engaged in desk-bound job.
It is reported that in England, obesity rates doubled during a period when energy intake reduced. Similarly in Canada, despite decrease in energy intake and an increase in physical activity obesity levels doubled. This could probably be due to increase in sedentary behaviour (more sitting time and non-ambulatory activities). Studies show that nearly 25 per cent of adults and children who watch television for 21 or more hours a week are obese. Obesity was considerably less among those who watch for five or less hours a week (less than 14 per cent). Similarly people who use computers for 11 or more hours a week have higher risk of obesity. This impact is much more among children and adolescents. It has been reported that among Indians, the risk of diabetes increases proportionately with increasing hours of TV viewing. Scientists now recommend “Stand up for your health”.
