Viibryd (Vilazodone) is a drug that was developed by Merck for the treatment of clinical depression. It was approved in the United States as an antidepressant medication in 2011. It functions as an atypical serotonergic antidepressant. Although some consider it to be similar to SSRIs, it differs in that it is unlikely to cause significant weight gain or sexual dysfunction.

While it does inhibit the reuptake of the neurotransmitter serotonin, it also acts as a partial agonist of the 5-HT1A receptor. It is believed that its agonism effect is responsible for minimizing unwanted side effects. Despite its more favorable side effect profile, it is unknown as to whether this drug is any more effective than current medications on the market.

Does Viibryd Cause Weight Loss or Weight Gain?

Many people that take Viibryd notice that their weight changes throughout treatment. Some people may lose weight during the first few months of treatment as a result of side effects like diarrhea or an appetite decrease. Others may notice that they gain a few pounds early in treatment, but their weight stabilizes. In an open-label 1 year study, it was found that the average amount of weight gained on this drug was slightly less than 4 lbs. (~3.75 lbs.).

On average, most people consider it to be a “weight neutral” drug in that it does not typically affect weight throughout treatment.  That said, it is important to acknowledge the fact that there are always outliers or individuals that do experience significant weight loss and gain contrary to the majority.

  • Source: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3369713/

How Viibryd Causes Weight Loss

Those that experience weight loss from the drug generally do so within the first 6 months of treatment. Those that are on the drug for a longer term actually are more likely to gain a few pounds. Viibryd is believed to cause weight loss initially as a result of its laxative effects (e.g. diarrhea) and increased energy.

  • Appetite decrease: Many people that take Viibryd may notice that their appetite decreases after they begin treatment. Anytime a drug decreases your appetite, there’s a good chance you’ll consume less calories and ultimately weight loss will ensue. It should also be mentioned that people who were coping with their depression by overeating (prior to taking Viibryd) may now feel less of an urge to eat as a means of coping. This leads to the person losing the weight that they may have packed on as a result of their depression.
  • Diarrhea: A significant number of people report experiencing diarrhea in the early stages of treatment. It takes awhile before the body adapts to the drug and diarrhea stops. Most physicians will recommend taking Imodium with Viibryd to help offset any laxative effects. If you notice laxative effects resulting from this medication, you’re probably going to lose some weight until they subside.
  • Increased energy: For some people, this drug has an activating effect, making them more energetic than they were prior to taking it. If you notice that you’ve become more energetic, you’re probably more likely to engage in physical activity or move around more than when you were depressed. When energy levels increase, exercise becomes easier and not as much of a chore.
  • Metabolism increase: Some people believe that their metabolism increases or stays neutral while taking this drug. If the drug boosts your energy and you start moving around more, the fact that you’re moving more will increase your metabolism. If the weight starts dropping and you aren’t doing anything different in terms of diet and/or exercise, it could be that the drug sped up your metabolism.
  • Nausea: If you feel nauseous as a side effect of this drug, eating may be somewhat difficult. The nausea alone makes it difficult to force down food even when you haven’t eaten. As long as this side effect persists, it’s going to be tough to get adequate calories. If you aren’t eating an adequate amount of calories, you’re going to lose weight. Fortunately most people notice this side effect eventually subsides.
  • Partial 5-HT1A agonist: The drug acts as a partial agonist at the 5-HT1A receptor, meaning it partially activates this receptor to produce an effect. It is believed that activation of this receptor is capable of offsetting weight gain that a person would experience if the drug solely functioned as a serotonin reuptake inhibitor. Among drugs that act as an agonist at this same receptor, weight gain is less common.
  • Vomiting: This is a side effect that some people experience that goes hand-in-hand with nausea. Some people experience nausea and actually vomit as a result. This is more common in the early stages of treatment when the nervous system is trying to adapt to the drug. If you end up vomiting frequently, you’re going to lose weight until it stops.

Note: It is unknown specifically what causes some people to lose weight while on Viibryd. However, most speculate that it is a combination of factors that are subject to individual variation.

How Viibryd Causes Weight Gain

Understand that most people do not notice any significant weight gain while taking this drug. If you do gain weight, it could be due to a variety of factors including: appetite increase, food cravings, metabolic changes, and social dining. Understand that the factors contributing to weight gain are highly based on the individual.

  • Appetite increase: Some people notice that their appetite increases after they start taking Viibryd. An increased appetite typically leads to eating more foods (possibly unhealthy foods) and ultimately weight gain. Individuals that lost weight as a result of poor appetite stemming from depression are likely to gain weight back during treatment as a result of appetite increasing.
  • Fat storage: Some believe that any drug inhibiting the reuptake of serotonin is capable of altering the way the body stores fat. If you notice that your body starts to store fat in places that it hadn’t prior to taking the drug, it could be a result of the medication. When the body stores more fat or fails to metabolize enough of it, you’re going to gain weight.
  • Food cravings: Another theory is that serotonergic drugs are capable of causing us to crave foods. If you notice that you crave foods, specifically carbohydrates (e.g. pizzas, pastas, etc.) and other sugary junk foods, there’s a chance this is from the drug. Compare your food cravings prior to taking Viibryd with how you feel now that you are taking it. Some people are able to notice a clear difference in the foods that they’re drawn to eating.
  • Hormone levels: Over a longer term treatment, there’s a possibility that this drug is affecting hormone levels. Regardless of what hormones the drug is affecting, this is a disruption in your body’s natural state of functioning. Any disruption in hormone levels could cause a person to gain more weight than usual.
  • Improved taste: Some people notice that their taste is dull and the flavor of most foods is relatively bland when they are depressed. When they are properly treated for their depression, their taste experiences a noticeable improvement. This marked improvement in taste could lead some people to eat larger portions of food.
  • Interaction effects: Never rule out the possibility that Viibryd may be interacting with another medication to cause weight gain. Although Viibryd is unlikely to cause weight gain as a standalone treatment, augmenting it with another medication may be an entirely different story. All interaction effects among medications aren’t well documented and are highly subject to individual variation.
  • Metabolism decrease: If you gain weight, the drug may have actually decreased the speed of your metabolism. Typically a major decrease in metabolism will not occur over the short-term. However, people that have been on the drug for a longer duration could notice subtle weight gain despite the fact that they’ve been eating the same amount of food.
  • Side effects: Not everyone experiences increased energy while taking this drug. Others may feel tired, groggy, or weak – making it difficult to exercise. If the drug is making you feel more sluggish or lazy than usual, your metabolism is probably going to decrease and you will naturally burn less calories than if you were active.
  • Social eating: Going out to eat with friends may become a routine among those that feel happier and less depressed. The only problem with social eating is that it is typically a major contributor to weight gain. If you find yourself going out to eat with co-workers, friends, etc. more than you did in the past, understand that this could be responsible for your weight gain.

Factors that influence weight changes on Viibryd

Regardless of whether you lose or gain weight while taking Viibryd, there are important additional factors that may be contributing. These factors typically include things like: the dosage you’re taking, your lifestyle and personal habits, how long you’ve been on the drug, as well as other medications that you’re taking.

1. Dosage

Most people are taking a dose anywhere from 10 mg to 40 mg. While the recommended dose is 40 mg, there are people that end up taking less due to a superior therapeutic effect. Others may end up taking more than 40 mg if this protocol is recommended by a physician. In any event, taking the minimal effective dose of this drug (and any drug) is a good way to minimize weight change while medicated.

The more you increase your dosage, the more you are disrupting your body’s homeostatic functioning. At higher doses, the drug has more control over your brain and nervous system, essentially rendering you helpless to the effects of the drug. At lower doses, there is less disruption within your homeostatic functioning, thus leading to less weight change.

2. Individual factors

Before blaming the drug for any weight changes you experience, it is important to consider individual factors that could contribute to weight change. Something as simple as not getting enough sleep could raise cortisol levels and thus storage of body-fat. Be sure to evaluate your sleep habits, dietary intake, the amount of exercise that you’re getting, your stress level, etc.

Understand that many lifestyle factors that you have direct control over can lead to weight gain or loss. Also know that genetics likely play a significant role in determining how you’re going to react to Viibryd. For this reason, it is recommended to consider the “GeneSight test” which examines your genetics and predicts which antidepressants will work best for you.

3. Time span

The duration over which you take this drug will influence the amount of weight you gain. Those that only take the drug for months are only likely to experience dramatic shifts in weight as the body adjusts to the medication. After the body has adjusted, weight typically stabilizes and people tend to remain weight neutral or gain small amounts of weight.

Realize that over time, you will eventually develop a tolerance to the drug and may need to bump up the dosage – leading to greater likelihood of a weight change. Due to lack of long-term studies, it is unknown how much a person’s weight will change if they are on this treatment for an extended term (i.e. several years).

4. Other medications/drugs

If you take any other medications and/or drugs, consider that they may be contributing to weight changes. Realize that drugs with stimulating properties are more likely to suppress appetite and speed up the metabolism, while sedating medications are more likely to increase appetite and slow the metabolism.

If you are taking another drug with Viibryd and you suspect that it may be responsible for your weight change, be sure to talk to a doctor to clarify this assumption. Also understand that there’s a possibility for an interaction effect between the Viibryd and the other drug, which could amplify any weight changes you experience.

Why Viibryd is considered a “weight neutral” antidepressant

In clinical trials, there were no significant weight changes among those treated with this antidepressant. Does this mean that everyone will experience no weight gain or loss during treatment? No, what it means is that on average, most people maintain the same weight throughout treatment as they were pre-treatment.

In studies spanning less than a year, there was no reported weight gain among those taking Viibryd. Other data reveals that those taking Pristiq for longer than a full year are likely to gain some weight, but the amount of weight gained is relatively insignificant – especially when compared to other medications. Therefore, most doctors will recommend this antidepressant for people who are reluctant to try medication for fear of weight gain.

How much weight will you lose/gain from Viibryd?

There’s no telling exactly how much weight you stand to lose or gain from taking Viibryd. Some people lose a significant amount of weight throughout their treatment, even over longer terms. Others notice minor fluctuations in weight throughout their treatment, but nothing significant enough to report. Despite weight gain being highly unlikely on this drug over the short term (occurring in less than 1% of cases throughout 8-weeks), there is a need for longer term data. On average, those that gain weight are only likely to gain 3.75 lbs. after 12 months of treatment.

Viibryd: Comparing weight changes with therapeutic effects

Assuming you dislike the weight gain (or loss) associated with Viibryd, it is important to compare these weight changes with its therapeutic effects. If you didn’t gain much weight and feel significantly less depressed than you did before you took it, it’s probably safe to say that the benefits significantly outweighed the side effects.

On the other hand, if you gained (or lost) a bunch of weight and the drug isn’t noticeably improving your depression, it may be worth pursuing a different treatment (or considering Viibryd withdrawal). Always take the time to compare the benefits with the drawbacks so that you’re able to objectively evaluate how you respond to this particular drug.

Did you notice weight changes while taking Viibryd?

If you noticed any weight loss or weight gain while taking Viibryd, be sure to share your experience in the comments section below. Understand that not everyone is going to have the same experience as you; the reaction you have to this drug will be largely individualized. To better understand your situation, it would be beneficial to discuss: the dosage you were taking, how long you had been taking Viibryd, and any other factors you can think of that may have contributed to your weight change.