Keeping a busy social life amongst lots of friends may keep people slimmer than spending hours on a treadmill, according to scientists.

They say that socialising and meeting with friends helps boost levels of 'brown fat' in the body which burns calories to generate heat.

Living in a stimulating, social environment was found to reduce abdominal fat in mice by half over four weeks, even if they ate more.

US researchers say that social stimulation aids weight loss by converting white fat into brown.

White stores calories and makes us fatter, while brown burns energy to generate heat.

Converting white fat into brown is notoriously difficult, normally requiring long term exposure to cold conditions or activating part of the body's nervous system.

However, scientists from Ohio State University now think that having a busy social life is an even more effective way of changing white fat into brown.

The team came up with their theory by studying the effects of various living environments on mice.

Those who lived alongside a greater number of mice, had more space and toys to stimulate them lost far more weight over the course of the study than their 'couch potato' counterparts.

Study author Dr Matthew During, whose team's findings appear in journal Cell Metabolism said: I'm still amazed at the degree of fat loss that occurs.

Explaining how new technology had threatened face-to-face socialising, he added: ‘It's not just a sedentary lifestyle and high calorie foods, but an increasing lack of social engagement.’

Co-author Dr Lei Cao said: ‘Loneliness is a profound factor for cancer and death; it's on par with cigarette smoking. Social engagement is very important.’

(Read by Nelly Min. Nelly Min is a journalist at the China Daily Website.)