If you're feeling desperate to lose weight, you are actually less likely to be successful in your efforts than people who are more satisfied with their bodies, a new study has found.

People who are extremely dissatisfied with their bodies are the least likely to have success with programs of dieting and exercise, say Dr. Michaela Kiernan and colleagues at Stanford University School of Medicine, whose research was published in the "Annals of Behavioral Medicine."

Two types of people face extreme difficulty losing weight, even when they combine exercise and dieting, the researchers found:

Overweight individuals who are extremely dissatisfied with their bodies, even if they're not significantly heavier than other participants in the study; and

Individuals with a history of losing and regaining weight.

During the research, the Stanford group assigned 177 men and women who were mildly to moderately overweight to one of two weight-loss programs. One group dieted, while the other took up the same diet and began an exercise regimen.

One year later, nearly half (49 percent) of the diet-and-exercise group successfully lost the targeted amount of roughly 10 to 15 pounds for a 5-foot, 9-inch man or 5-foot, 4-inch woman. However, only 26 percent of the diet-only group met this goal.

Strongly linked with success among the diet-and-exercise group, the researchers found, was participants' initial satisfaction with their bodies. Members who started out more satisfied were more than twice as likely to succeed as their deeply dissatisfied counterparts (55 percent, compared with 26 percent).

Researchers speculated that those extremely dissatisfied with their bodies may be uncomfortable exercising in a class with others and end up not going to class regularly. For them, exercising at home or with a friend may be more appealing.

Those without a history of repeated weight changes also were more likely to meet the weight-loss target than those with such a history (63 percent, compared with 35 percent), the study results showed.

So many people failed within the diet-only program that no successful subgroups were identified, emphasizing the importance of changing diet and exercise habits, it stressed.