Gabapentin: Does it Lead to Gaining Weight?

Dr. Christopher McGowan
November 11, 2022

Most people will experience fluctuations in their body weight from time to time during the normal course of life. The reason weight goes up or down is typically related to dietary habits and regular physical activity levels. Sometimes, though, the standard explanations may not tell the whole story, particularly for those who are on prescription medications. Such medications typically have side effects that can include changes like gaining weight. One example of a medication that seems to be connected to unexplained weight gain is gabapentin.

What Is Gabapentin?        

Gabapentin is an anticonvulsant medication that is used to treat some types of seizures and nerve pain. Sold under the brand names Neurontin, Gralise, and others, gabapentin was first approved for use by the Food and Drug Administration (FDA) in 1993. It was originally designed to interact with GABA (gamma-aminobutyric acid), the neurotransmitter in the brain that is primarily responsible for reducing excitability in the nervous system. Gabapentin was initially used as a way of improving the effectiveness of other anti-seizure medications, but it is now prescribed for a variety of conditions: 

  • partial seizures 
  • neuropathic pain 
  • anxiety 
  • sleep disorders 
  • drug dependency 
  • multiple sclerosis (MS) 
  • hot flashes 
  • restless leg syndrome or tremors     

Though gabapentin can be used to treat these many different conditions, most of the time it is prescribed for people suffering from epilepsy, a neurological condition that is defined by bursts of activity in the brain that result in a seizure. Gabapentin is used to treat partial seizures that occur in a specific part of the brain, but it isn’t effective at treating generalized epileptic seizures that affect the whole brain. The other main condition gabapentin is helpful with is postherpetic neuralgia, a type of neuropathic pain that stems from damaged nerves. Neuropathic pain can also be caused by shingles, diabetes, fibromyalgia, or a spinal cord injury.  

How Does Gabapentin Work?

Perhaps surprisingly, scientists aren’t entirely sure how gabapentin works in the brain. While it is similar in structure to the neurotransmitter GABA, it doesn’t appear to actually bind to GABA receptors. Instead, gabapentin seems to bind to certain calcium channels in the central nervous system. This action then stimulates release of GABA, which decreases the kind of neural excitability characteristic of seizures. But it also seems to reduce the release of other neurotransmitters that are involved with pain transmission; this action is the reason it is used for neuropathic pain.   

Possible Side Effects of Gabapentin

As with many other medications that affect neural activity and the way neurotransmitters operate, gabapentin is also known to have certain side effects. The most common side effects reported are feelings of dizziness and drowsiness, though they usually are only experienced when a patient first starts taking the medication. Below are some other less common but relatively mild side effects that are possible while taking gabapentin: 

  • weakness or fatigue 
  • swelling of the extremities 
  • involuntary eye movements 
  • ataxia, involuntary muscle movements or problems with balance or speech
  • headaches
  • nausea or vomiting 
  • diarrhea 
  • dry mouth
  • increased appetite 
  • erectile dysfunction 
  • memory problems   

There are a few more serious side effects and potential complications, but they are exceedingly rare. In less than 1% of cases, patients have experienced suicidal thoughts or a preoccupation with death. There is also the possibility of having trouble breathing if gabapentin is taken along with opioids or other depressants. In patients who have certain allergies, there is an additional risk of anaphylaxis, an allergic reaction that can cause itchiness, swelling, and even death.  

Does Gabapentin Cause Weight Gain?   

One other potential side effect of gabapentin is weight gain. In studies that looked into gabapentin’s impact on weight, a small number of people (3%) gained around five pounds of body weight during a six-week trial. Doctors aren’t precisely sure why the drug might have this effect, but it appears to be at least in part because of the tendency for appetite level to increase while on the medication. As appetite increases, so also does the likelihood of overeating or choosing foods that have generally higher calorie counts.  

Another possible explanation for mild weight gain is fluid retention, especially in the limbs (also known as peripheral edema). The reason for this fluid buildup is unknown, but researchers have theorized that it has to do with the effect of gabapentin on calcium channels and more water being drawn into the body because of dilation in the arteries. A different avenue being explored as the cause of weight gain is the impact of other side effects on physical activity levels. Fatigue, dizziness, problems with balance all have the potential to discourage movement and exercise; combined with increased appetite, a person taking gabapentin may very well be more likely to gain weight.   

Avoiding Weight Gain While on Gabapentin

In summary, it does appear that weight gain can be a side effect of taking gabapentin, regardless of the reason the medication was prescribed. However, the potential for gaining weight is related to the indirect effects of the drug and not any specific action in the brain or elsewhere in the body. Overall, weight gain should be viewed as a potential but relatively unlikely side effect of gabapentin. And even if a patient does experience some increase in body weight, it will probably be minor and it may even be temporary, especially if it is because of water retention.  

Nevertheless, even a little bit of extra weight may be unwelcome to most people. To avoid gaining extra weight while taking the medication, then, a patient may want to first speak with their doctor about alternatives. If there are none, the best course of action is to be more mindful of eating habits by eating smaller portion sizes at meals, avoiding high-calorie snacks and desserts, increasing the proportion of lean proteins, and finding ways to increase weekly physical activity levels. It’s important to note that if the medication is causing any weight gain, do not stop taking it without consulting with your doctor. 

How to Lose Weight and Keep it Off

Ultimately, everyone’s weight management goals are personal and based on their own preferences and experiences. Taking gabapentin might inadvertently lead to putting on a few extra pounds, but it won’t cause you to become overweight or obese by itself. If you’re just trying to lose a few of those holiday pounds, for instance, making some minor modifications to your diet and activity levels can probably get you where you want to be in a matter of a few months. 

For others, though, the weight loss journey is much more involved and may require a different approach. At True You Weight Loss, we understand how seemingly fruitless it can be to rely on the traditional methods of losing weight. That is why we offer several alternatives that are designed to help you make the long-term changes necessary to finally find the freedom you’ve been seeking. If you’d like to learn more about our non-surgical weight loss procedures, please contact us today to request a consultation. We would be glad to talk with you about a new start to your journey. 

Dr. Christopher McGowan
Dr. Christopher McGowan

Dr. Christopher McGowan, MD, a leader in endobariatrics, specializes in non-surgical obesity treatments and is triple-board-certified in Internal Medicine, Gastroenterology, and Obesity Medicine. Renowned for pioneering endoscopic sleeve gastroplasty (ESG) with over 2,000 procedures, his global influence and research contributions define him as a top expert.

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