There's a common trope in Hollywood celebrities who gain weight and receive attention for it. They talk about how much healthier and better they feel about themselves at higher weight - and then they immediately lose weight and talk about how much healthier and better they feel about themselves.

Severely obese people who aren't famous also experience much better spirits once they shed weight through diet, lifestyle changes or medical intervention but Valentina Ivezaj and Carlos Grilo of the Yale University School of Medicine write in Obesity Surgery that it is not a psychological magic bullet.

Ivezaj and Grilo set out to investigate how prone bariatric patients are to still experiencing depressive symptoms, and especially if such symptoms increase markedly or not at all, after post-surgery. Their study is the first to examine patients with discernible worsening depressive symptoms six and 12 months following gastric bypass surgery.

Self-reported questionnaires were completed by 107 patients with extreme obesity before they underwent gastric bypass surgery, and then again six and 12 months after the procedure. They were asked to reflect on their levels of depression, possible eating disorders, their self-esteem and general social functioning. Of the 107 participants, 94 were women and 13 were men, 73 were white and 24 had completed college.

Consistent with previous research, Ivezaj and Grilo observed that most people who had undergone this procedure were in much better spirits. In fact, most patients reported experiencing a normal and improved mood at six and 12 months after surgery. However, in some cases negative mood changes started to creep in between six and 12 months after the operation, with 3.7 percent of patients reporting that they felt discernibly more depressed 12 months post-surgery.

Between six and 12 months after the operation, however, even more patients (13.1 percent) reported increases in depressive symptoms. These changes went hand-in-hand with significantly lower levels of self-esteem and social functioning.

They advise that levels of depression in patients be measured six to 12 months after they have had such bariatric surgery.

"The majority of patients whose mood had worsened discernibly experienced these mood changes between six and 12 months post-surgery, suggesting this may be a critical period for early detection and intervention, as needed," explains Ivezaj.

"The increases in symptoms of depression are also notable given that they were associated with other difficulties including lower self-esteem and social functioning," adds Grilo.

The authors note that the increases in depressive symptoms were indicative of only subthreshold or mild mood disturbances. They also indicated that future research is needed to determine whether these mood changes continue to worsen over time for this group.