When Antidepressant Medications Cause Weight Gain

Your weight loss options may be limited.

Posted Feb 26, 2020

People suffering from mental illness are more likely to be obese and prone to cardiovascular disease and diabetes than the general population. An article in Psychiatry Advisor by Nicola Davies cites several articles describing the increased incidence of obesity among those who are or have been mentally ill.

The poor diet, limited exercise, social isolation, and mood-induced overeating of those with mental illness may contribute to the weight gain. And, when the mental illness is treated successfully, a normal lifestyle and weight may resume. Sadly, weight gain may also be a side effect of the treatments used to bring about a remission. Most antidepressants, mood stabilizers, and drugs used for schizoaffective disorder and schizophrenia can cause anywhere from a 5-to-100-pound weight gain.

Often cardiovascular problems and diabetes, consequences of the obesity, follow. The psychotropic medications may decrease calorie utilization by decreasing physical activity, due to fatigue, but much of the weight is gained due to a significant increase in food intake. Nighttime bingeing, persistent cravings for snacks, and the doubling of meals can cause a rapid and persistent weight gain.  

The risks of obesity have been well characterized. Yet surprisingly, there are few weight-loss options designed specifically for this population. Recently, at a meeting with a group of psychiatrists to discuss this problem, one of the physicians said that her patients are never weighed, nor does she talk about weight-loss programs.

“We know many of our patients will gain weight, but our first priority is to get them well,” she said. “If we discuss weight gain, they may decide not to be treated, or they will become more anxious, depressed, or stressed. If weight gain does occur, we try to find another equally effective drug with less weight-gain potential. But sometimes that is not possible.”

Her responses were reasonable but left unanswered the question of who will help the patients if they gain weight rapidly and substantially? Might NAMI, the National Alliance on Mental Illness, be a source of information about weight-loss programs for this population? A look at a recent newsletter mentioned that an eating disorder awareness week was coming shortly. Perhaps there would be some discussion about individuals whose eating was out of order, i.e. disordered, because of a side effect of their medication. Perhaps NAMI was working with the National Eating Disorder Association to find establish support and maybe even research to stop the weight gain side effect. But no, there was no mention of awareness of this subgroup of overweight and obese individuals.

Fortunately, a few weight-loss programs for mentally ill individuals have been developed and tested for their efficacy. One such program, inShape, offers a personal health mentor who interacts with a patient to offer continual nutritional guidance and exercise support. Participants in the program are helped to participate in community activities to decrease social isolation. Even though some of the participants had major depressive disorders, mood disorders, and schizophrenia, after a year, most showed significant weight loss.

An 18-month-long weight-loss intervention study with similar personalized support also found positive results among those with severe mental illness.

These programs are important because of their ability to bring about weight loss among a population who otherwise would have difficulty following conventional weight-loss programs. However, the labor-intensive nature of the interventions might make it difficult to extend their use to large numbers of mentally ill people. Moreover, no information is available as to how long weight loss is maintained once the support systems are removed.

These comprehensive weight-loss interventions were directed at those who suffer from severe mental illness and presumably would not be able to take advantage of the many programs available to the general population. But those whose mental illness is being successfully treated by their medications shouldn’t need specific diets or physical activity support any more than anyone in the population who has to lose weight. Their therapist, if asked, could recommend any diet: fasting, keto, home-delivered calorie-controlled meals, Weight Watchers, a Mediterranean-type food plan, vegetarian, or vegan.

So why the fuss? Just because the weight was gained as a side effect of a psychotropic drug doesn’t mean that it won’t come off if fewer calories are eaten than needed.

But it may not.

This group of overweight and obese individuals is not like others who need (or want) to lose weight because they eat more than they need. This group may never have had to diet, had they not been on their psychotropic medications. They are taking one or more drugs that have undermined their ability to feel full after eating, regardless of the size of the portions. Their drugs are causing them to snack, especially on sweet and starchy foods, which is something they may never have done before going on their medication. Their drugs may be interfering with their metabolism, making it hard to lose weight within a reasonable period of time.

They need a diet that does not decrease serotonin levels in their brain because, for most, the drug(s) they are taking is attempting to increase serotonin activity. (Carbohydrate must be eaten alone or with very small amounts of protein for serotonin to be made.)

They need a diet that will remove their persistent need to snack and eat meals by increasing satiety. (Serotonin is the neurotransmitter in the brain that increases a sense of satisfaction after eating.)

They need an exercise program that may be able to increase their metabolism by increasing muscle mass. (Because of drug-associated fatigue, the exercise program must be aware of the patient’s limitations.)

They need a support group that understands that they are overweight or obese because their medication took away their control over their food intake. (The psychological distress at the unexpected weight gain must be dealt with.)

Let us hope that the programs and support to help these individuals restore their pre-treatment
weight will be available soon.


“The Trajectory from Mood to Obesity,” Wurtman, J and Wurtman, R, Curr Obes Rep 2018; 7:1-5.

“Lifestyle Intervention for People With Severe Obesity and Serious Mental Illness,” Aschbrenner, N, Scherer, E, Pratt, S, et al, Am J Prev Med. 2016; 50:145-53.

“A behavioral weight-loss intervention in persons with serious mental illness,” Daumit, G, Dickerson, F, Wang, N et al, N Engl J Med. 2013; 368): 1594-602.