According to new research, if your partner embarks on a new weightlosing regime, it's likely that they're about to leave you.

Sociologists (my people!) in Germany say that happy couples put on weight because there is less pressure on them to be attractive and by taking themselves 'off the market' they give themselves permission to let it all hang out.

Conversely, those who are unhappy often set out to change their appearance in order to bag themselves a new partner to grow fat and unattractive with until the cycle starts again.

Or someone dies of an obesityrelated illness, which gets everyone off the hook.

We sociologists are full of terrible news.

There you were looking forward to parading your svelte partner in front of your jealous friends when all along they have been plotting to dump you for some tiresome gym bore that paints their muscles with gravy browning and only eats egg whites at weekends.

Study head Thomas Klein said: 'When you are on the look out for a new partner, people try to be as thin and attractive as possible.

However, people in a relationship feel less pressure and often put on weight.' He added that possible warning signs that you will be in imminent need of a new status on Facebook include your partner's sudden obsession with the gym or their involvement in sports and new diets.

To be fair, if I was with someone who developed a sudden obsession with the gym or a new sport or diet, I'd hope that they were planning to leave me – only one thing is more dull than listening to someone bang on about calories or training programmes and that's doing them yourself.

•This article was original published on November 14, 2011