We're all guilty of the thinking that if we just lost a few (or more) pounds, we'd be happier.

But according to a new study, losing weight will not make you happy ... and may even make you more depressed.

For four years, researchers at the University College of London followed 2,000 overweight individuals who were trying to lose weight. At the end of the four years, 14 percent had lost 5 percent or more of their body weight, 15 percent gained more than 5 percent, and 71 percent stayed the same weight.

Here's where it gets crazy ...  While all the study participants were healthier physically, the ones who lost weight were twice as likely to be depressed as those who gained weight or maintained their weight. The ones who lost weight also reported a lower overall sense of  well-being.

Why would someone be depressed if they lost weight? According to lead study author Sarah Jackson, Ph.D., while they can't determine the exact cause, she believes there is something about the dieting process that makes people unhappy. "Although dieters may feel a sense of satisfaction in seeing the numbers of the scale go down, each pound lost requires considerable willpower and sacrifice to achieve," Jackson says. "It is easy to see how restricting food intake, resisting temptation, and, in some cases, even avoiding social occasions that center around food could take a toll on well-being." (Shape)