Effexor (Venlafaxine) is a common antidepressant medication that is classified as an SNRI. It functions by preventing reuptake of the neurotransmitters serotonin and norepinephrine. It differs from standard SSRI medications in that it also targets norepinephrine, which often elicits a stimulatory effect on the user. Some believe that increasing norepinephrine in addition to serotonin makes it less likely that a user will experience weight gain as a side effect.

Effexor and Weight Gain

A majority of individuals prescribed Effexor aren’t really concerned with whether they will gain weight while taking it. They are generally just hoping that it will improve their symptoms of depression. Effexor is considered the first SNRI ever approved (1993) for the treatment of major depression, and there are a significant number of success stories from those that have benefitted from this drug.

Doctors generally consider Effexor to be a “weight neutral” antidepressant in that it is less likely to cause weight gain than other antidepressants, but that doesn’t mean it’s impossible to gain weight while taking it. There are still plenty of individuals that notice they pack on some pounds after they’ve been taking Effexor.

How Effexor Causes Weight Gain: Possibilities

While Effexor is regarded as being mostly “weight neutral,” it doesn’t mean that nobody will gain weight while taking it. Some people still gain weight and there are a variety of possible reasons that could account for the increase in weight.

  • Appetite changes: Some individuals who are depressed don’t eat enough. When they get proper treatment for their depression, their appetite comes back and they start eating again. For people who weren’t eating enough as a result of their depression, packing on some weight is inevitable when the appetite returns. Among others, an increase in appetite may be obvious. They may feel significantly more hungry than usual after they’ve taken the Effexor.
  • Carbohydrate cravings: Neurotransmitter changes are often responsible for regulating “cravings.” There are studies that demonstrate close ties between the serotonin system and the propensity to crave carbohydrates. If you’ve been taking this drug and you all of a sudden feel like a pasta addict or are constantly buying candies to eat, it’s probably partly influenced by the drug.
  • Drug interactions: It is possible that Effexor is interacting with another medication that you’re taking to promote weight gain. When people are taking multiple drugs, they often believe that one specific drug is to blame – and in many cases they’re correct. However, it could also be that synergistically, the drugs interact to produce the effect of weight gain.
  • Fat storage: The storage of extra fat in your body is less likely when taking Effexor due to the fact that norepinephrine increases should (in theory) speed up your metabolism. However, Effexor acts on serotonin to 30 times the extent than it does on norepinephrine. Some would consider its effects on norepinephrine negligible. If your body starts storing more fat, it’s likely stemming from the serotonergic effects.
  • Hormonal alterations: Taking antidepressants can alter hormone levels, especially when taken over the long term. Really the only way to track this would be to get hormone levels checked prior to taking a drug, and then checked again after months of treatment. Some individuals notice that certain hormone levels shift and this may account for changes in weight.
  • Metabolic changes: Despite the fact that this drug acts on norepinephrine, it doesn’t mean that all metabolic effects will be positive. Some theorize that the norepinephrine increase will offset any metabolic changes resulting from serotonin increase. That said, serotonin is targeted to a significantly greater extent by this medication, which could result in a slowed metabolism.
  • Motivational changes: Some people notice that their motivation changes as they take Effexor. For some people the motivation may be a marked improvement, but for others, motivation may plummet. Not everyone experiences increased energy from this medication and is able to stay weight neutral. A drop in motivation makes it less likely that you’ll go to the gym or engage in activities that require physical movement.
  • Side effects: Not everyone will be free of side effects while taking Effexor. Despite the fact that this drug is touted as being activating, some people may actually become drowsy, tired, or lethargic while taking it. This often leads people to sleep more and get less exercise which inevitably slows the metabolism.
  • Social eating: Those who take this drug and start to become less depressed or anxious often become social again. This results in them being more likely to go out with friends to get food. Whether it’s dining at restaurants, going out for lunch, etc. – frequently eating out with friends is a quick ticket to weight gain.
  • Taste improvement: If you were depressed and are no longer, often times food tastes better. It becomes pleasurable to eat foods and go out to eat. The improvement in taste is a subjective statement, but often times altering neurochemistry can result in a perceived taste improvement. This leads some people to seek out more food because they are deriving pleasure from the taste.

Note: It may be difficult to determine which of these theories is accurate based on your individual scenario. It may be that none are accurate, or it may be that a specific combination of these factors are to blame. For example, someone may experience lethargy from the medication, crave carbohydrates, and store more fat than they would being off the drug.

Factors that influence weight gain on Effexor

There are a variety of factors that may influence the amount of weight you gain from Effexor. This includes things like your dosage, individual habits, the duration for which you’ve taken the drug, and whether you are currently taking any other medications.

1. Dosage

What dosage are you currently taking of Effexor? Those that are taking higher doses often end up gaining more weight than those at lower doses. The primary reason for this weight gain at a higher dose is that the drug has more influence over your natural functioning. Those taking a lower dose may not experience much of any weight fluctuation simply because their body’s natural functioning hasn’t become as disrupted.

Anytime you “double the dose,” you are essentially doubling your risk for weight gain. This is all too common with people that increase their dosage and then wonder why they start to pack on the weight. At this point the drug has significant influence over the individual’s brain and physiological functioning.

2. Individual factors

Although a medication-induced effects may be to blame for weight gain, it is nearly impossible to rule out individual habits and lifestyle factors. Many people don’t realize that things like: stress level, hormones, dietary intake, exercise, genetics, and physiology can determine whether someone gains weight. It is important to consider that your stress level may have increased and/or your dietary intake may have changed since starting to take Effexor. Always look at your individual habits and lifestyle factors that could account for weight gain.

3. Time span

Over what duration have you taken Effexor? People that have taken it for a longer duration are more likely to gain weight than those who only have taken it for a short term. Taking it over the long term (e.g. years) often results in tolerance, which makes the brain reliant on the drug for functioning. Unfortunately when tolerance is established, the dosing is generally increased, which simultaneously increases the likelihood of weight gain.

When a person takes Effexor for years, it may alter hormone levels and elicit unknown physiological changes. All of the changes that the drug makes may account for an increase in weight. There are often cases of people who take a drug for awhile, don’t notice any weight gain, but after a couple years they’ve packed on more weight than expected.

4. Other medications

If you are taking multiple drugs, it is important to always consider that the other drugs may be to blame for the weight gain. It is also important to consider that Effexor and the other drug may both be contributing to your weight gain. In some cases the other drug(s) and Effexor will interact to actually amplify the amount of weight that you gain; it depends on the other drug you are taking. Be sure to always consider the possibility that other medications are responsible for your increase in bodyweight.

Why Effexor is regarded as being “weight neutral”

In comparison to other antidepressants, Effexor is often considered to be “weight neutral.” This is due to the fact that serotonergic effects may be partially offset by noradrenergic effects. The norepinephrine increase is capable of speeding the metabolism and reversing some “weight gain” effects brought upon by the serotonin.

  • Energy boost: For some people, even the minor action on norepinephrine can serve as a significant energy boost. This increase in energy is thought to be activating, helping the person stay physically active and maintain motivation to exercise.
  • Metabolism increase: Certain people experience some weight loss while taking Effexor due to its effect on metabolism. Some believe that even the small increase in norpinephrine is capable of helping certain people lose weight by speeding up their homeostatic metabolism.
  • Stimulatory: While this isn’t a “stimulant,” it does act on the neurotransmitter norepinephrine, which is of stimulatory nature. Increasing levels of norepinephrine is known to increase central nervous system activity and cortical arousal. Therefore its stimulating properties are thought to offset some of the weight that could be gained as a result of serotonin.

How much weight will you gain from Effexor?

There’s no telling exactly how much weight you will gain from taking this drug. As was mentioned, some people may gain a small amount of weight, others will remain at the same weight, while certain individuals may actually shed a few pounds. For SNRIs, there is no exact estimate of weight amount you will gain.

It is thought that nearly 30% of people taking high-doses of Effexor will complain of weight gain. Whether weight will be gained on standard or low doses remains controversial. In most cases, the amount of weight gain will be highly subject to individual variation. It is believed that throughout the course of treatment, an individual could stand to gain between 5 and 10 lbs.

  • Source: http://www.ncbi.nlm.nih.gov/pubmed/15260908

Will everyone gain weight while taking Effexor?

No. Not everyone will gain weight from this drug. There are cases of people who’ve taken this drug and not noticed any weight gain at all throughout the course of their treatment. In order to minimize the potential for weight gain, it is recommended to always take the minimum effective dose. This prevents the drug from further disrupting homeostatic metabolism and other physiological functions (e.g. fat storage).  There are new genetic tests being conducted like GeneSight in effort to determine what side effects you will be most likely to experience.

Effexor: Cost-Benefit Analysis

If you are taking Effexor, it is important to conduct a cost-benefit analysis in regards to any weight gain that you experience. For some people, gaining weight is a pretty big deal and can actually make them even more depressed. If the medication is working well to treat your depression and anxiety, you may be able to justify small or moderate changes in weight while undergoing treatment.

However, if you think the weight gain is significant and aren’t getting much benefit from the drug, it’s a relatively choice to switch medications and/or embrace Effexor withdrawal. Do your best to objectively consider both the benefits and drawbacks associated with your current treatment regimen. If the drawbacks significantly outweigh any benefits, you may be better off with a different treatment.

Did you gain weight while taking Effexor?

Realize that not everyone is going to have the same reaction to taking Effexor in regards to weight or side effects. If you have taken Effexor or are currently taking it, feel free to share whether you noticed any weight gain or other weight changes throughout your treatment. It may help others to know how much weight you gained, the dosage you were taking, how long you’ve been taking it, and any other possible factors (e.g. other meds) that may have contributed to weight gain.