You can't outrun a bad diet, say experts

Excessive sugar and carbohydrates are behind the obesity crisis rather than physical inactivity, claim three experts in the British Journal of Sports Medicine.

"It is time to bust the myth of physical inactivity and obesity: you cannot outrun a bad diet," said cardiologist Dr Aseem Malhotra who co-wrote the editorial.

Regular exercise is key to staving off serious disease, such as diabetes, heart disease, and dementia.

But they say calorie laden diets now generate more ill health than physical inactivity, alcohol, and smoking combined.

"The public health messaging around diet and exercise, and their relationship to the epidemics of type 2 diabetes and obesity, has been corrupted by vested interests."

Celebrity endorsements of sugary drinks must end, while health clubs and gyms need to set an example by removing them and junk food from their outlets.

As well as blaming excessive sugar, the authors say studies suggest that excessive carbs are no better.

But CSIRO research director Professor Manny Noakes said it was myth to say sugar and carbs alone were responsible for obesity.

"Australians eat over 30 per cent of excess kilojoules from indulgence foods," she said.

"Some may be high in sugar and carbohydrate, but many may also be high in fat and salt.

"Eating for good health and wellbeing will not be achieved by focusing on avoidance of one nutrient."

Exercise has many benefits, but particularly for weight loss maintenance rather than weight loss, she added.