Food, fat or physical inactivity? What’s to blame for diabetes?

Diabetes affects people in the prime of their productive life. Unfortunately all the “good” things associated with modern life are risk factors for diabetes. In other words, diabetes affects healthy people and the conventional risk factors include age, high intake of foods with sugar and fat, obesity, sedentary lifestyle, stress — all of which are characteristics of today’s lifestyle.

Among the obvious risk factors, importance of physical activity is often not recognised. One major reason has been the lack of sensitive tools to assess physical activity. Moreover, the optimal level of physical activity needed for human beings to maintain good metabolic and cardiovascular health is not clearly known.

There is no doubt that physical inactivity is a major cause of obesity. Many scientific studies have proved that physical inactivity is detrimental, even in the absence of obesity. In fact a large proportion of people who develop diabetes in India have a Body Mass Index that would be considered non-obese by western standards. The scientific explanation is that Indians have comparatively more fat mass than muscle mass. Recent studies have shown that physical inactivity may be a more important risk factor than bad/high fat diet for diabetes and obesity in developed countries. Increasing physical activity helps weight reduction in obese persons, which is beneficial in improving metabolism.

Studies have shown increasing obesity rates in Australia, the U.K., and the U.S., although sugar intake in Australia and the U.K. showed a slight decline. In the U.S., a small increase in sugar intake occurred but this was much smaller than the increase in obesity rates. Furthermore, the U.S. had massive increases in sugar intake early in the 20th century, but no increase in obesity rates was seen. Therefore, declining total daily energy expenditure is a more likely cause of the obesity epidemic, causing metabolic disorders such as diabetes.

In a recent paper, published in Lancet 2012, I-Min Lee and colleagues analysed the effect of physical inactivity on non-communicable diseases and concluded that physical inactivity is a major risk factor for NCD along with obesity and smoking.

It has also been noted that in India the average physical activity among the urban population is much lower compared to western countries. This is true not only for adults but also for children. This situation needs to change and the proof is reflected in the number of Olympic medals we win compared to China.

One of the major reasons is the increased amount of time adults and children spent in front of televisions and computers. One study in Chennai showed that the number of hours of watching television per week was directly proportional to the prevalence of diabetes. This study was conducted when there were only 25 TV channels. Other studies have shown that physical activity improves glucose and fat metabolism even in non-obese persons and can even prevent the onset of diabetes in those at risk (Indian Diabetes Prevention Programme, Diabetologia, 2006).

There are many misconceptions regarding healthy exercise programmes. We need to realise that increasing the number of steps taken during working hours in an office or at home adds to physical activity. For example, take the staircase instead of the elevator, walk to the market instead of driving, walk in the railway station or airport especially if the train/flight is delayed. These small steps will substantially improve physical activity in the Indian scenario.

Walking is one of the best physical activities. To those who complain that they do not have time to walk, the answer is: make time —half an hour daily — for walking, it will add 10 more years to your lifetime.