People who suddenly start dieting while they're in an apparently steady relationship are secretly prepping to drop their other halves.

According to a study, happy couples don't worry about their weight because there is less pressure to look attractive.

A sociologist 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.

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

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