We are genetically programmed to put on weight. Our genetic make-up, eating habits, and physical inactivity are some of the causes of overweight. Our appetite is elastic and it follows Parkinson’s Law. The law says that work expands so as to fill the time available for its completion. When applied to appetite, it says that more we to eat, more we have to eat. “Collecting the maximum number of calories with the least amount of effort is, after all, the dream of every creature,” writes Elizabeth Kolbert in The New Yorker. Obesity happens when we eat more calories than we use. The calorie imbalance over time causes obesity.

Michael Power and Jay Schulkin, the authors of The Evolution of Obesity, blame our brain for obesity epidemic. Human brain is heavy calorie demanding part of our system. It weighs 2 per cent of the body weight but consumes 20 per cent of the total energy intake. Our present cranial capacity (about 1,300 cc) is more than three times the cranial capacity of our distant ancestors. As our cranial grew our digestive tract shrank. This “expensive tissue hypothesis” forced man to obtain more energy-dense foods than his fellow-primates were subsisting on. The evolution of obesity is the result of eating high calorie and easy to digest food.

Because food was scarce, early humans had to stockpile food in themselves for later use. Our body thus developed a biological system to store energy (fat) and our brains and bodies adapted to thrive in these environmental conditions. Austerity was the rule for hunter-gatherer societies. Now, in most countries, food is easily available. We are consuming more energy than we burn. “We evolved on the savannahs of Africa. We now live in Candyland” write Power and Schulkin. The positive energy balance is the cause of obesity.

Obesity is a global phenomenon. The excess weight may result in type 2 diabetes, coronary disease, hypertension, various kinds of cancers, gallstones, and osteoarthritis. Obesity problem is no longer restricted to resource rich countries. It is one of the biggest drains on national health-care budgets, say Francis Delpeuch, Bernard Maire, Emmanuel Monnier, and Michelle Holdsworth, authors of the book Globesity. An interesting observation made by Delpeuch and his colleagues is that it is possible to be overweight and malnourished at the same time.

This is due to the overdependence of modest income group people on cheap calorie-packed food. The real cost of fattening food and soft drinks have dropped in recent years, resulting in alarming increase in overweights. David Kessler, author of The End of Overeating, says reengineered fashion products (known also as “eatertainment” to create “lot of fun in your mouth”) are the real culprits. Researchers say animal brain reacts to sweet, fatty food the same way addicts react to cocaine. Brian Wansink, author of Mindless Eating, says that people have no idea how much they want to eat or, once they have eaten, how much they’ve consumed. “Give them a lot and they eat a lot.”

What should be done to deal with the problem of obesity? The World Health Organisation (WHO) has suggested some action plans to encourage better eating and fitness. These include imposing a “fat tax” on caloric snacks, improving health education, regulating food and beverage advertising, and limiting the foods available in public facilities. Since obesity is related to brain function (for example, the influence of the smell, taste and appearance of food on the stimulation of hunger), one suggestion is to treat obesity as a psychological/psychiatric disorder. Since obesity develops over years, obese should expect a similar time scale to return to his or her ideal weight after starting treatment. Quick-fix weight loss solutions are unreliable.

The writer is a biotechnologist and ED, Birla Institute of Scientific Research, Jaipur