Just who is your lover losing the weight for? People dieting while in a relationship are preparing to break up with their other half

Don't feel too flattered if your partner starts losing weight - it might be for somebody else.

People who suddenly start fighting the flab while they're in an apparently steady relationship are secretly preparing to drop their other halves, a study claims.

Happy couples don't worry about their expanding waistlines because there is less pressure to look attractive, sociologists claim.

Professor Thomas Klein studied the link between happiness and body weight and said the warning signs could include a sudden obsession with the gym or getting involved in sports and diets.

'When you are on the lookout for a new partner people try to be as thin and attractive as possible,' Professor Klein said.

Consequently, when one half in a relationship starts slimming down it can be interpreted as 'preparing for the partner market'.

Professor Klein, of the University of Heidelberg, added: 'People in a relationship feel less pressure and often put on weight as they do not watch their weight so much.

Content: Happy couples don't worry about their expanding waistlines because there is less pressure to look attractive, sociologists claim

'In a happy partnership, people tend to get fat. With less competition, the weight difference is low.'

But a crisis in a relationship can end the gluttony, he says. And that could end up with both partners dropping weight.

Researchers studied more than 2,000 people aged between 16 and 55. Among the findings was that people in couples generally weighed more than single people hoping to attract a partner in a