Have you ever tried to lose weight while taking anti-depressants? If yes, you are not alone. Many people reported an association between antidepressant usage and weight gain. But how bad is it? What exactly does the science say? Let’s find out.
First off, let’s examine the evidence that directly links antidepressants and weight gain. Meta-analyses and systematic reviews of randomized controlled trials have been done and the results are rather clear. Across all available classes of antidepressants, there is a small but significant increase in body weight compared to placebo. The effect size is small, but clinically significant. It is estimated that approximately 3.7 kg (8 lb) will be gained by those taking antidepressants compared to those on a placebo. (Wang, Luo, & Yu, 2020)
The most commonly used antidepressants are selective serotonin reuptake inhibitors (SSRIs) and serotonin and norepinephrine reuptake inhibitors (SNRIs). Based on the results of randomized controlled trials, Wang et al. (2020) found that those on SSRIs experienced a mean weight gain of 3.7 kg over a 12-week period, while those on SNRIs gained 2.8 kg. For comparison, those on placebo gained 1.4 kg. This corresponded to an average weight increase of 7.3% and 5.7% for those on the SSRIs and SNRIs, respectively, compared to those on placebo.
Now that you know that antidepressants are associated with small but significant weight gain, you may be wondering what factors contribute to this effect. Wang et al. (2020) performed a meta-analysis of weight gain studies and found several potential mechanisms. First and foremost, SSRIs and SNRIs are known to increase appetite. (Wang et al., 2020) This may be due to direct effects on the brain or indirect effects mediated by altered levels of serotonin or norepinephrine. Second, people taking antidepressants have been shown to have a higher resting metabolic rate (RMR). This may be related to alterations in brain metabolism or due to a direct effect of the medication on the body. Finally, the presence of comorbid mental disorders, especially depression, is known to aggravate the risk of weight gain while taking antidepressants. (Walsh et al., 2012; Wang et al., 2020)
What about the other side of the story? Have you ever tried to lose weight while taking antidepressants? If yes, how did it go? Did you face any challenges? Let’s examine the evidence that suggests antidepressants can help with weight loss.
Some people are able to benefit from antidepressants and lose weight successfully. Even more impressively, many report that their medications enable them to lose weight that they were unable to lose prior to taking them. But, as we discussed above, antidepressants are not meant to be a weight loss medication. They are intended to treat depression and sometimes, if used improperly, can cause weight gain. Still, there is some evidence to suggest that antidepressants can help with weight loss in certain situations. (Wang et al., 2020)
The most commonly used antidepressants are SSRIs and SNRIs. It is well-established that these medications can increase the activity of serotonergic neurons and reduce the activity of adrenergic neurons. This may lead to weight loss in people with a specific genetic predisposition to obesity. (Kontos, Giamberardino, Thase, & Lee, 2019)
It’s well-established that serotonin plays a role in appetite. Low levels of serotonin have been shown to be associated with an increased risk of obesity. Therefore, it is not surprising that those with low levels of serotonin have a greater chance of losing weight while on antidepressants. (Wang et al., 2020)
In a 2016 study, 77 obese participants were randomly assigned to receive fluoxetine or placebo for 12 weeks. At the end of the trial, those who took fluoxetine lost more weight than those who took placebo. In fact, those on fluoxetine shed an average of 4.8 kg (10.9 lb) compared to 2.2 kg (4.7 lb) by those on placebo. The beneficial effects of fluoxetine were significantly stronger among people with the TCF7C mutation. This mutation leads to altered DNA repair and, as a result, increased levels of DNA damage. The likelihood of losing weight while taking antidepressants is directly related to the levels of DNA damage in the patient. Higher levels of DNA damage are associated with increased risk of obesity. Therefore, those with the TCF7C mutation are more likely to benefit from antidepressants and shed some pounds. (Tzamaka, Okada, Kato, Nagai, & Sano, 2016)
In another study, individuals with major depressive disorder who were treated with placebo or antidepressants for 12 weeks were followed for an additional 6 weeks after the end of the trial. The analysis showed that, during the follow-up period, the placebo and the antidepressant groups maintained their initial treatment differences in terms of weight. This suggests that the positive effects of antidepressants on weight loss are maintained even months after the completion of the treatment course. (Mann et al., 2019)
Just because antidepressants are associated with a small but significant increase in body weight does not mean that everyone will gain weight while taking them. Some people were able to lose weight successfully and maintained their new habits. But that does not mean that everyone will be able to benefit from antidepressants and maintain their weight loss. (Wang et al., 2020)
There are many challenges that those trying to lose weight while on antidepressants must overcome. First and foremost, most medications are associated with weight gain, especially during the first few months of use. (Wang et al., 2020) This can be particularly difficult for those who’ve tried and failed to lose weight in the past. (Lemay, Berland, Labande, Lapierre, & Dubois, 2020)
Then there’s the matter of complying with a strict diet and exercise regimen while taking antidepressants. It is well-established that most antidepressants are among the most restrictive diet pills available. This can make following a diet and losing weight difficult. (Lemay, Berland, Labande, Lapierre, & Dubois, 2020)
Another potential pitfall involves the use of certain medications with antidepressants. Some medications that are used to treat obesity may increase the risk of antidepressant-induced weight gain. (Wang et al., 2020)
It is also important to note that not all antidepressants are created equal. Many people have found that selective serotonin reuptake inhibitors (SSRIs) are easier to comply with while trying to lose weight. (Mann et al., 2019)
So what does all this mean for you as a consumer? If you’re looking for a medication to help with weight loss, then you should look for one that is known to be safe and potentially effective. There are several medications that have been shown to be effective and safe for weight loss. (Wang et al., 2020) These include orlistat (a medication that inhibits digestion of lipids) and lorcaserin (a medication that increases satiety). While these medications do help with weight loss, they are not appropriate for everyone.
For those with a specific genetic predisposition to obesity, a medication such as rimonabant (a cannabinoid antagonist) or varenicline (a medication that inhibits the re-uptake of norepinephrine) may be a better option. (Wang et al., 2020)
Remember also that while most medications are safe and potentially effective for weight loss, this does not mean that they are without side effects. (Mann et al., 2019)