Value of exercise in fighting obesity a "myth" claim experts

A leading cardiologist says that the notion that exercise can help obese people lose weight is a “myth” and that they should instead be encouraged to eat more healthily. They also say that unhealthy diets, not lack of exercise, are to blame for the obesity epidemic.

The controversial claims are made in an editorial published in the British Journal of Sports Medicine, jointly written by London-based Dr Aseem Malhotra, and two other experts, one from South Africa, the other from the United States.

They said that “manipulative marketing” by the food industry undermined government initiatives to combat obesity, and that “vested interests” distorted public health messaging relating to diet and exercise.

But the head of the body that sets health guidelines for England and Wales insists that any attempt to underplay the value of exercise in weight loss is “idiotic.”

The editorial’s authors say that as levels of obesity have soared in the Western world over the past three decades, levels of exercise have remained almost static.

“This places the blame for our expanding waist lines directly on the type and amount of calories consumed,” they assert.

Citing the Lancet global burden of disease programme, they said “poor diet now generates more disease than physical inactivity, alcohol and smoking.”

They also said that PR by the food industry “uses tactics chillingly similar to those of big tobacco” in leading many to believe, incorrectly, “that obesity is entirely due to lack of exercise.”

They added: “It is time to wind back the harms caused by the junk food industry's Public Relations machinery. Let us bust the myth of physical inactivity and obesity. You cannot outrun a bad diet.”

Dr Malhotra told BBC News: "An obese person does not need to do one iota of exercise to lose weight, they just need to eat less.

“My biggest concern is that the messaging that is coming to the public suggests you can eat what you like as long as you exercise. That is unscientific and wrong."

However, the views expressed in the editorial were countered by a number of other experts, who said that exercise, alongside a healthy diet, had a vital role to play in fighting obesity.

But Professor Mark Baker from the National Institute of Health and Care Excellence, which sets guidelines for health in England and Wales and says people should follow "well-balanced diets combined with physical activity" insisted it was "idiotic" to downplay the value of exercise.

And Ian Wright, director general of trade body the Food and Drink Federation, rejected criticism of the food industry’s PR on the subject.

He said: "The benefits of physical activity aren't food industry hype or conspiracy, as suggested. A healthy lifestyle will include both a balanced diet and exercise.

Referring to the editorial, he said: "This article appears to undermine the origins of the evidence-based government public health advice, which must surely be confusing for consumers."

Philip Insall, director of health at the sustainable transport charity, Sustrans, said that in the case of the UK, levels of physical activity had fallen over the past half century and said exercise was vital not just in combating obesity, but a range of other health conditions.

“Whilst going easy on the sugar and consuming a balanced diet is essential to managing obesity and our overall health, playing down the importance of physical activity is a misleading message,” he said. “Both are very important.

“From 1961 to 2005, levels of physical activity in the UK dropped by 20% and if current trends continue, will reduce by more than 35% by 2030.

“As a direct result, diabetes, cancers and many more health disorders are becoming increasingly prevalent.

“The UK Chief Medical Officers recommend 150 minutes per week of physical activity for adults, and 60 minutes a day for children, because this is beneficial to health and helps prevent a whole range of diseases – not just obesity.

“Healthy levels of activity can be built into a person's day much more easily than some might think,” he added.

“Most of us can build activity into our daily routine by choosing to walk or cycle everyday journeys, instead of taking the car or bus.”