See your physician regularly to ensure proper monitoring of gastrointestinal side effects and weight loss or gain while taking Prozac. If weight loss or gain persists, your physician can determine if you need to to stop taking the drug or modify the dose. Antidepressants That Cause Weight Loss. The majority of antidepressants cause some weight gain. There are a small number of antidepressants that have been shown, in some cases, to cause a loss in weight. When treating depression, the most important thing is to treat the depression. However, since weight gain can lower a person's self esteem. Prozac is also known to be a slight stimulant and on the medication you might notice a little weight-loss or remain weight neutral, unlike other SSRIs. So coming off and gaining weight wouldn't be unusual. Also, if you are actively trying to have a baby, your body may be preparing and your hormones are definitely changing. The more sex you have the more estrogen your body makes and that can. Do both cardio & weight training. Doctors give trusted answers on uses, effects, side-effects, and cautions: Dr. Jones on weight loss after stopping prozac: Eat healthfully. Try to eat at least 5 servings of vegetables & 4 of fruit per day. Although Prozac can cause some initial weight loss, it may cause weight gain in the long run. What can you do to lose weight when using Prozac? Although Prozac can cause some initial weight loss, it may cause weight gain in the long run. What can you do to lose weight when using Prozac? Menu. Verywell Mind. Prozac (Fluoxetine) and Weight Gain. Share Flip Email Search. Search Clear GO. More in. Hi Everyone. I started taking prozac 20 mg, then 40 mgs, about 8 months ago. At first I noticed a little weight loss (4 lbs) but after being on it for about 6 months I noticed rapid weight gain. Some antidepressants can cause weight loss. For example, duloxetine and bupropion have been reported to lead to weight loss in some people. For example, duloxetine and bupropion have been reported. Prozac can often cause loss of appetite, nausea, and diarrhea, which may contribute to weight loss. Often, these side effects go away with time. Also, since weight gain can be a depression symptom, treating the depression can lead to weight loss. I thought these 2 meds were known to be weight neutral or cause weight loss. My doctor knows my concern about the weight issue as this is something I have never fought to maintain while everything else in life seems to be a fight. Stopping suddenly can cause serious side effects. Your doctor will help you safely stop the medication. Don't take Prozac or other forms of fluoxetine if you're allergic to fluoxetine or any of.