If your partner suddenly starts shedding the pounds and hitting the treadmill, be wary, as their new flab-free look might not be for your benefit, according to new research.
The study investigated the link between happiness and body weight and found that people who start dieting while in a steady relationship, are secretly planning to give their partner the elbow.
Researchers at the University of Heidelberg studied more than 2,000 people and found that happy couples generally don't worry about gaining weight because they feel less pressure to look attractive to others.
Therefore, if one half starts a strict diet regime and becomes a gym bunny overnight, it could be a signal that they aren't as happy as they appear - and may be planning to give their other half the boot, or simply "preparing themselves for the partner market", as the study suggests.
"When you are on the lookout for a new partner people try to be as thin and attractive as possible," Professor Thomas Klein from the study told the Daily Mail.
"People in a relationship feel less pressure and often put on weight as they do not watch their weight so much. In a happy partnership, people tend to get fat. With less competition, the weight difference is low," added Professor Klein.
Another study recently revealed that married couples do less exercise than single people.