Is Your Partner (Suddenly) Losing Weight for Someone Else?

Don't feel too flattered if your partner suddenly starts hitting the gym — it might be for somebody else.

People who begin fighting the flab while in an apparently steady relationship may be preparing, consciously or not, for the partner market. That is the provocative conclusion of a study by Professor Thomas Klein of the Max Weber Institute for Sociology at the University of Heidelberg, published in the Cologne Journal of Sociology and Social Psychology.

Klein surveyed around 2,000 people and found a consistent pattern: people in happy relationships tend to gain weight, while singles and people going through relationship crises tend to lose it. The explanation he offers is competitive pressure. Singles who are looking for a partner watch their weight and exercise more, hoping a good figure improves their chances. In a happy partnership, that pressure largely disappears — couples eat together, relax together, and the pounds creep on.

"When you are on the lookout for a new partner, people try to be as thin and attractive as possible," Klein said. A relationship crisis, he argues, can end the comfort-eating — and restart the dieting. Weight loss in that situation, he suggests, can be read as a kind of preparation for the partner market: with a better figure, the chances of finding someone new go up.

He also noted a wrinkle: where competitive pressure on the partner market is weaker, the weight gap between singles and couples shrinks. The mechanism, in other words, isn't romance itself — it's the audience.

So the next time your other half develops a sudden obsession with the gym, the salad bar and the bathroom scale, you might ask: who exactly are they trying to impress?