Heart-friendly town-planning

A study of older (aged 45+) Indian adults recently published in the journal Preventive Medicine finds that while several drivers of cardiovascular diseases are present amongst them, a high level of belly fat (central adiposity) and physical inactivity are by far the most prevalent.

When measured using the WHO benchmark of a waist–hip ratio of greater than 0.9 for men and 0.81 for women, 77.2 per cent were found to have excess belly fat (ranging between 95.3 per cent for the population of Chandigarh and 63 per cent for Mizoram), with 73.9 per cent having low levels of physical activity as well.

In sharp contrast, the proportion of overweight and obese individuals, at 17.7 per cent and 6.8 per cent respectively, was much lower. This is an exciting finding, because body weight is most strongly linked to total calorie intake and is difficult to change (because it needs fundamental changes in food habits). On the other hand, belly fat is much easier to address, because it can be reduced through modest levels of daily exercise.

Belly fat is strongly associated with insulin resistance and is linked to several diseases, such as high blood pressure and diabetes. Insulin resistance refers to a weakened response to increases in insulin levels in the body, and our evolutionary history provides a clue to its origins.

We evolved in an environment with poor food and salt availability and a high risk of attack, injury and infections. In such an environment, during periods of stress— including pregnancy as well as infection/inflammation—since the body needs to maintain higher levels of glucose in the blood, insulin resistance proved to be a helpful adaptation.

However, when the environment changed to one in which food and salt availability became plentiful, insulin resistance moved from a helpful response essential to our survival to one now linked to severe disease.

Belly fat is now so familiar that it is considered a normal part of ageing. Some cultures even regard it as an attractive physical feature because it is a sign of prosperity or perhaps—in an evolutionary carryover— of the presence of insulin resistance, historically so crucial for survival.

Unfortunately, it is now well understood that belly fat is strongly linked to high blood pressure, high blood sugar and higher cholesterol levels—the three most important risk factors for cardiovascular disease, even amongst people with a normal weight.

People with excessive belly fat who also have high blood pressure are even more likely to develop diabetes. It may interfere with digestion in their daily lives too, resulting in problems like heartburn produced by oesophageal reflux. It hurts sleep quality and can cause lower back pain as well. In addition, belly fat is associated with an increased risk of developing cancer and clinical depression.

To deal with the challenge of belly fat, one must look at its underlying causes. High calorie intake and inadequate physical exercise are linked to it. However, unlike overall body weight, belly fat has been shown to respond well to even moderate levels of exercise.

Exhorting people to eat less and exercise more has rarely been effective. Increasing the price of sugar and cooking oil, as has been done in some countries, effectively reduces the calories consumed. The political and policy challenges associated with bringing about similar changes in the Indian context are, however, likely to be extremely high and perhaps even insurmountable.

Many cities, including London and New York in developed countries and Addis Ababa in the developing world, have sought to explicitly design their cities to enhance the level of exercise that people can get as a part of their daily routines.

To increase the levels of exercise, more parks—while adding an attractive feature to cities—have not been found to be effective. Instead, public transportation systems that require people to walk to and from their residences to get to bus and train stops on smoothly connected, safe, brightly lit and well-built pavements have had a demonstrated effect on the level of exercise that people get daily.

In India, while the rates of formal urbanisation are still considered low (at close to 30 per cent), an analysis of the night lights data obtained by satellites indicates that much of the population already lives in habitations so dense that they would be classified as urban in many countries.

As these dense habitations transform into formal cities, they offer an opportunity to build these walk-friendly features into their designs.

As these urban areas evolve, even independently of any health benefits that might accrue, they need to invest in public transportation so that the denizens of the city can move around safely and economically without the need to use private vehicles, which require expensive roads and result in a much higher degree of pollution and road traffic injuries.

Building good pavements is also essential because otherwise, as tends to happen in most cities currently, pedestrians spill onto roads, resulting in congestion and an increased risk of accidents.

Ensuring that these pavements link smoothly to the city’s public transportation infrastructure becomes the next logical step—which, happily, also has the desirable side-effect of reducing belly fat and a direct impact on lowering the prevalence of cardiovascular disease and diabetes.

The poor state of our healthcare system makes designing our emerging cities—where most of our people are likely to reside—as pedestrian-friendly and equipped with effective public transport even more critical.

After all, diseases like diabetes and high blood pressure pose perhaps one of the greatest challenges we are likely to confront as a people.

The good news is that our average calorie consumption and associated obesity levels is, at least for now, relatively low compared to the developed world. The bad news is the prevalence of poor waist-to-hip ratios.

Even the alarming fact that over 75 per cent of our adults have big bellies and rarely, if ever, do even moderate exercise may have a silver lining—it offers some hope that we might be able to reverse the trend.

(Mayanka Ambade is an assistant professor at IIT, Mandi. Nachiket Mor is a visiting scientist at The Banyan Academy of Leadership in Mental Health, Chennai. Courtesy: The Billion Press)