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Topamax For Weight Loss: How It Works, Dosage, & Individual Variation

Topamax (Topiramate) is an anticonvulsant medication that is primarily used for the treatment of epilepsy, but has also been approved for migraine prevention and as an adjunct to phentermine for weight loss. It is also commonly used as an off-label medication to treat bipolar disorder as well as borderline personality disorder, but there is no conclusive evidence to support its efficacy in these conditions.

Despite the drug being effective in reducing the prevalence of seizures, its mechanism of action that produces therapeutic effects is unknown. Some speculate that it alters voltage-gated sodium channels as well as various calcium channels within the brain. Others believe that it may affect GABA receptors, AMPA receptors, and carbonic anhydrase isoenzymes.

Topamax & Weight Loss

Regardless of how the drug works, it is known that it is often used as an off-label pill to lose weight. Although not everyone will lose weight from taking Topamax, many people lose a significant amount throughout their treatment. It is also important to mention that although it isn’t approved as a standalone drug for weight loss, it is included in the formulation known as “Qsymia” which is approved specifically for weight loss.

How Topamax Works for Weight Loss

The mechanism behind how Topamax works is relatively misunderstood. It has been tested in clinical trials for weight loss, but was inevitably discontinued as a result of people experiencing a significant number of adverse effects. Although the drug never lasted in clinical trials for weight loss, many doctors are knowledgeable that patients taking Topamax are likely to lose some weight. Below is a list of factors that may influence how Topamax works to promote weight loss.

  • Addiction centers of the brain: It is speculated that Topamax may be targeting the addiction centers of the brain with its mechanism of action. Individuals that previously sought out pleasure-inducing substances like food, alcohol, and drugs no longer do so. This is because Topamax may change neural pathways within the addiction control center of the brain. It may also reduce overexcited nerves within this region.
  • Appetite reduction: Many people taking this drug experience appetite reduction or suppression as a side effect. It isn’t exactly known as to how this drug may supress appetite, but some believe it ties into the reward center of the brain. The drug may numb or alter the way rewards are processed, leading to people feeling less hungry or experiencing less cravings for food.
  • Hormone alterations: Another school of thought suggests that the drug may be altering levels of hormones such as cortisol and leptin. Specifically the drug may be decreasing the amount of leptin that is found in cortisol, as well as cortisol itself. Leptin is a hormone that regulates appetite, and when reduced, people tend to feel less hungry. Also when cortisol (the stress hormone) is reduced, the body tends to store less fat, which will lead to weight loss.
  • Disorientation: Those that take Topamax may feel so disoriented as a result of their treatment, that they may have a difficult time functioning and remembering to actually eat. While this may sound silly, this drug can have potent effects on memory, lead some people to feel dizzy, and result in profound disorientation. Those that feel disoriented as a result of treatment may forget to eat or may not want to eat as much.
  • Ketosis: This drug may also be affecting levels of blood glucose as well as insulin, which could promote ketosis, a state by which the body uses its own fat as fuel. When in ketosis, your body uses up fat stores to give you energy, often resulting in significant weight loss. This is how individuals on “low carb” diets lose weight. Some speculate that Topamax may artificially induce ketosis.
  • Loss of taste sensation: Many people notice that food loses its pleasurable taste and the “yum factor” seems to be missing while medicated. This typically leads people to eat smaller portions and/or less overall food. Some have complained that Topamax makes food taste bland, “grey,” flavorless, and in some cases just “bad.” If your taste buds feel like they’ve been hijacked, it’s a result of the drug.
  • Metabolism changes: While many people don’t believe that Topamax speeds up the metabolism, some do. If you have maintained the same diet pre-drug as during treatment, and aren’t doing anything noticeably different, but are losing weight, it could be a result of a faster metabolism. This theory is less likely to be true due to the fact that this isn’t a psychostimulant medication, but one that should be considered.
  • Saliva production: A specific theory as to why Topamax reduces ability to taste has to do with reduced saliva production. Those that take the drug tend to experience reductions in the amount of saliva produced on a daily basis. When saliva is reduced, it can result in poorer taste and people may lose some of their normal appetite – leading to weight loss.
  • Side effects: Many people experience drug-related side effects that can also contribute to weight gain. Common effects that lead to weight loss include: diarrhea, nausea, and vomiting. If you are experiencing diarrhea and/or vomiting, it’s a no brainer that weight loss is inevitable. If you are nauseous all the time, you probably won’t want to eat as much; this is common sense.

Note: What leads to weight loss in one person may not be the same as in another. Therefore it is important to understand that certain factors may be more influential in one person’s weight loss than another. For example, one person may predominantly experience poorer taste, while another may have a reduced appetite and diarrhea.

Factors that influence weight loss on Topamax

There are other factors that may influence weight fluctuation as a result of Topamax treatment. These include things like: the dosage you ware taking, time span over which you’ve been taking it, your lifestyle and general habits, genetics, as well as other medications that you take.

1. Dosage

It is known that this drug tends to help people lose weight, and there is a relationship between weight loss and the dosage taken. Those that take higher doses, tend to lose more weight than those on lesser doses. It should be speculated that dose in relationship to bodyweight as well as tolerance may also play a role. For a smaller statured individual, less of a dose may produce more weight gain than the same dose in a larger person.

Doctors will generally prescribe specific dosages based on the condition for which you are taking the drug. Those that are on Topamax for seizure prevention are likely to be on a higher dose than those for migraine prevention. The lower the dose, the less physiological influence the drug will have, leading to less weight change. If your goal is to avoid weight loss, you should be taking the “minimal effective dose.”

2. Time Span

The duration over which you’ve been taking Topamax can also play a role in determining how much weight you’ve lost. Someone who has been on the drug for a week and is just adapting to its effects may not experience as much weight change as someone who has taken it for several months. Over the short-term, you’re less likely to notice weight fluctuations in comparison to when you’ve taken it for a few months.

Those that have been on the drug for an extensive period may notice that weight loss stops once tolerance is developed. At a certain point, you’re likely to reach a peak in the amount of weight you lose simply due to the fact that your body will adapt to the drug.

3. Lifestyle / habits

Many people end up losing varying degrees of weight while on Topamax due to lifestyles and habits. Someone who isn’t getting proper sleep, is over-stressed, is eating junk food, and avoiding exercise may not lose as much weight as someone who is doing the opposite.

If you are eating healthy, getting a little bit of exercise each day, are sleeping well, and keeping stress to a minimum, you may be more likely to lose weight. Daily habits account for many individual differences in amount of weight lost while taking this drug.

4. Genetics

While we don’t know exactly how this drug interacts with a person’s genetics, many genetic factors determine how much weight you’re likely to lose in comparison to someone else. Certain people may experience considerable weight loss from this drug, while others may remain weight neutral or even experience weight gain.

These differences in reactions may be partially explained by genetic variation. Fortunately there is new technology in development like GeneSight that predicts how you’ll react to drugs like Topamax.

5. Other drugs

If you are taking other medications, it is important to consider interaction effects as well as how they may influence your weight. For example, if you are on an SSRI or antipsychotic, you may be more likely to eat more food, regardless of how dull Topamax makes your taste buds. Any medications that make you more inclined to eat typically offset the weight loss effects of Topamax.

It should also be mentioned that if you are on stimulant-related medications such as Adderall or Wellbutrin, you may end up experiencing a synergistic weight loss effect. In other words, since you will be on multiple medications that can cause weight loss, the amount of weight you lose will be more significant than if you were just taking Topamax as a standalone treatment.

Should you use Topamax just for weight loss?

Probably not. Obviously this isn’t a medically accepted use of the drug, and most doctors wouldn’t allow it. If you were specifically struggling with weight, they may prescribe Qsymia, which contains Topamax as part of its formulation. Many people that struggle with seizures and are overweight typically are taking the drug primarily for seizure reduction, but may be pleasantly surprised when they also lose weight.

If you are using this drug just to lose weight, it may be difficult to put up with some of the neurological side effects such as memory impairment, dizziness, etc. While some people are willing to take any drug in order to lose weight, you really should be weighing the pros and cons before sacrificing mental performance in order to look skinnier.

Topamax weight loss dosage…

Some research suggests that there is an ideal daily dosage of Topamax specifically for weight loss. Those that consistently take between 100 mg and 200 mg of Topamax daily, have reported that weight loss is virtually effortless. Most people taking the drug within this dose range (assuming they aren’t on other treatments) end up losing between 15% and 20% of their baseline bodyweight. Some speculate that dosages above 200 mg may result in more drastic weight loss.

Will everyone lose weight from taking Topamax?

Not everyone is guaranteed to lose weight on this medication. There is a lot of individual variation such as diet, habits, genetics, other medications, etc. that can have a huge impact on someone’s weight. That said, it is estimated that weight loss is among the most common side effects of the drug Topamax.

Most evidence suggests that weight loss occurs among 11% and 26% of those taking the drug. It should be mentioned that a select number of individuals can experience a counterintuitive reaction of weight gain during their treatment, but this is very uncommon.

Topamax’s therapeutic effect vs. unwanted weight loss

Those that are taking the medication for the purpose of treating a condition like Bipolar disorder may not like the weight loss. If you are already relatively skinny, you may have a problem with looking even skinnier. Although most people look forward to losing weight while on a medication, not everyone shares that perspective. If you are losing a ridiculous amount of weight on this drug and don’t like it, be sure to talk to your doctor about other options and/or Topamax withdrawal.

Also if you like the weight loss, but find the drug ineffective for the primary condition for which it was intended to treat, you’ll likely need to try something new. Others may find the drug effective for treating a condition, and may like the weight loss, but the other side effects such as memory loss may be too profound to justify continued usage. Always evaluate how you’re doing on the drug throughout your treatment.

Did you lose weight while taking Topamax?

If you are a person that has taken Topamax and lost weight, be sure to share your story in the comments section below. It may help others to know the dosage you took, how long you were on the drug, as well as how quickly you noticed the weight loss. Be sure to mention why you think the drug caused you to lose weight (e.g. lost your appetite) and other potential lifestyle factors that may have also contributed to your weight loss.

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{ 88 comments… add one }
  • Kerryn August 29, 2018, 6:27 am

    On 200mg daily for migraine and no weight loss in sight, bummer.

  • Angela August 15, 2018, 5:24 pm

    I have been taking a combination of Topamax and Wellbutrin, along with Diethylpropion (appetite suppressant) solely for the purpose of losing weight, not for headaches or mood disorders since March 2018. My starting weight was 184. I am a 46 years old, female. I am currently 145 pounds. With a BMI of 25.

    It works for me! The side effects of the Topamax alone in the beginning were tough to deal with. Back pain was my main complaint. I actually went to the doctor thinking I had a bad kidney infection. I didn’t. It was the side effect of the medication. I will continue the Topamax for about another month and then I will wean myself off.

    If you are considering losing weight this way, ask your doctor about this combo. It worked for me!

  • Nikki July 14, 2018, 3:21 am

    I started taking Topiramate in March due to Intracranial Hypertension. I have lost 63 lbs in 4 months. Primarily because all my food addictions have been “switched off” and I suffer a lot from nausea. But that is a small price to pay after years of struggling to lose weight.

  • Jen July 13, 2018, 6:36 pm

    I’ve been on Topamax for 5 years for seizures 100mg twice a day. I’m a 5’5.5″ tall female, 45 years old, and weigh 156 lbs. When I first started taking it I was 180 lbs and lost 60 lbs fast. I was too skinny at first. My tastebuds definitely changed and carbonated drinks taste flat so I haven’t had soda in 5 years.

    I follow a clean diet of organic fruits, veggies, grass-fed dairy, pastured eggs, grass-fed beef, wild caught fish, and healthy fats, nuts, seeds, and sprouted grain bread. I drink water, coffee, green tea, and wine. I am also on Effexor, Pravastatin, ER Oxycontin, Seroquel, and I take a lot of supplements like vitamins, greens, probiotics, and fish oil.

    My weight loss plateaued after about 6 months and I began gaining weight back at the 2 year mark. I started loosing weight slowly again about 6 months ago. I think it revved up my metabolism at the beginning, then my body adjusted. I had a hysterectomy before taking Topamax so I cannot say how those side effects are, but it does make me forget words in the middle of a conversation.

    Feel dizzy, very dry mouth, and if I wasn’t taking it with the PTSD medications I’m on – I would probably be as big as a cow. I think it counteracts the weight-gaining effects of my other meds. Also I don’t have seizures anymore. For me the side effects are worth it. Drinking a lot of water helps with fogginess in the morning.

    Also taking it with a meal helps. I don’t recommend it as just a diet pill, though. The weight loss is only temporary at the beginning and you have to take at least 100-200mg a day to see a difference. Once you start taking Topamax, you’re pretty much on it for life.

    I have to have my liver enzymes and A1c, an lipid panel checked every 6 months and I’ve heard coming off this drug is a nightmare. So if you don’t have seizures or migraines – I’d tell you it’s not worth it.

    • Tracy July 25, 2018, 7:33 pm

      Why do you think you started losing again 6 months ago?

  • tawnya May 29, 2018, 11:47 am

    I have been taking Topamax for about 11 months now and I have lost just about 100 lbs. My dosage is 75 mg twice a day. I also have incorporated 5 days a week movement. I hike each morning at least 3 miles or at least get a walk in with a group of ladies that are on the journey to be healthy with me.

    I have stopped all soda and no alcohol as well since I started the medication. I figured if the doctor had enough faith in me to start this I had to be willing to have enough faith to give it my all and change the lifestyle once and for all. I didn’t want another diet or something that would just gain it all back again plus more.

    It has been great. I have added a stationary bike so when I watch movies at home I do biking which has made my doctor overjoyed. We have a chart of my weight and it keeps going down which is great. I have also thrown out my scale and the only time I weigh in is at the doctor’s because health is not a number for me anymore.

    It’s being able to do those 3 miles and maybe not being out of breath or adding a little extra. I also do not buy anything “diet” and I read my labels. I use as much fresh foods as I can and don’t go out to “fast” food places almost at all.

    I occasionally still go to sit-down restaurants and thats fine. I use real butter and olive oil. I just stopped poisoning my system and punishing myself for doing it.

    I started putting life back in to my years. I am not sure this is what the comments section is for, but this is how my life has changed so I wanted to share.

  • Anthony April 4, 2018, 6:28 am

    I started talking Topamax for debilitating migraines that were becoming more and more frequent! Almost two or three a week. My stress level was through the roof. In nine months I lost forty pounds – went from a 36” waist to a 29 (a little too thin). I started on 50 mg twice a day then 200mg at night. The weight loss has stopped, but more important – no more migraines!

  • Kristy March 23, 2018, 2:47 am

    I started Topamax in 2010 for migraines and seizure like episodes. It helped with both and weight immediately fell right off me. Nothing else ever helped me successfully lose weight so when I lost 30 pounds I was really happy. Weight loss stopped after about 5 months and my normal appetite came back.

    I stopped taking Topamax after about 2 years because I wanted get pregnant and side effects with pregnancy are risky. I gained all my weight back. I started taking topamax again in 2017 and again immediately lost 15 pounds. I’m still on it but my weight loss has stopped and appetite has returned to normal.

  • Michelle J February 20, 2018, 10:36 pm

    I started taking topamax December 2017 25mg, I take 4 pills daily for migraines. Before I started, my migraines and headaches were really bad, and I weighed approximately 148lbs. Now I’m down to 133lbs, my diet has changed significantly and I’m very active so that also contributes to the weight loss.

    As for my migraines/ headaches they’re non existent since I started the medication. The side effects I’ve experienced in the beginning of taking the medication were mainly mood swings, horrible back pain, tingling in the hands and feet, and slurring or forgetting words/ phrases.

    The only side effects I experience now are the tingling and that’s usually during my intense workouts in the mornings before eating or taking my daily dosage.

  • Philip January 7, 2018, 4:39 pm

    I started with 25mg and recently went up to 50mg. I’m a male, six feet tall and I lost 104lbs in 5.5 months. Now weighing at 149lbs and I feel amazing. Of course this is with exercise and a strict diet.

    This medication is truly great but there are times it makes one feel sluggish. But I can’t remember the last time I had a migraine and I can’t imagine my life without it.

  • Janice March 26, 2017, 10:43 pm

    I have been on Topiramate (Topamax) 200mg and Phentermine 30mg and sometimes 37.5mg for a year now. I have lost 60lbs and seem to have slowed down, however, the doctor seems to think I should have lost more. I’m happy with this. I have noticed the taste of soda being bad and some foods not tasting the same. Also I do get full really fast and only eat one or two meals a day. That really drives my family crazy they are all used to 3 full meals a day. I will stay on this as long as the doctor will let me. It has been a Godsend for me with very few side effects except for the soda – which I don’t drink anyway.

  • MARYBETH SUNDERMANN March 19, 2017, 5:38 am

    I took topomax at a high dose for 2 years. I was 5’2″ talk and weighed 125lbs at the beginning. I lost 30 lbs in 6mos. Then I got horrible case of Shingles and lost another 10lbs. At 85lbs I looked AWFUL and was weaker and had more memory loss than I could handle. So I stopped it. I gained it all back within 3mos!! The problem is no one tells you that once you stop and start again, the 2nd time there is no weight loss. None. No one can explain to me WHY? Anyone know? Thanks!

  • Korinne February 14, 2017, 10:48 am

    I’ve been taking topiramate 25mg in the morning with my phentermine for weight loss for several months but I have seen a HUGE spike in positive mood change as well. I’m not sure if it’s because of the drug or reclaiming my body size though. I’ve lost about 25 lbs and am pretty stable weight right now, but I’m taking half the dose of both top/phent of what I’m prescribed because the couple of times I’ve tried to take the second topiramate 25 mg pill in the PM I get really bad insomnia.

    I normally have insomnia but this was jittery all night long bad! I’m considering trying my second pill at lunch without the phentermine to see if that helps me lose the last few lbs w/o the jitters. If that works I may cut the phentermine out completely as a test to see if I can sleep better. I’m not obese but was prescribed it due to complications (bad back does better with less weight to support).

    I’m definitely NOT experiencing the drowsiness, I have way too much energy and constantly need to find outlets for it. I’ve always been like that but I think these drugs have amplified the proclivity by a lot!!! It’s so good to hear about the soda thing! Lol. I literally thought the soda manufacturers made a bad batch of diet Dr Pepper! I couldn’t figure it out! 😆

    I’ve always had a bad memory and so far it doesn’t seem worse with this drug. Fogginess is way less than the pain pills the VA tries to give me for my back. I can’t take them unless my back is really bad or I can’t focus at work. Maybe this pill is amplifying that? But when I don’t take pain pills I’m fine so who knows. I’m also not getting headaches like before so there are lots of wins with this drug for me if I can fix my sleep issues. :)

  • Brenda Edwards February 8, 2017, 11:01 pm

    I was curious about the effects of Topamax after my psychiatrist put me on it today (50mg). I’m 5’7″ and weight 254. I had gained over 70 lbs over 18 months after being on Abilify (30mg) for bipolar disorder, so they think that this could counteract the weight gain from that drug and actually help me lose the weight again.

    I’m not looking forward to the fogginess that some have mentioned, but not worried about the soda side effect (I rarely drink it already). I am on a low carb/high protein diet and do cardio 30 minutes a day, plus circuit training 3 times a week. It looks like others with that combination have had success in losing weight, so I’m excited about that.

  • Lisa January 22, 2017, 2:03 am

    I have been taking Topiramate 50 mg for 3 months now for migraines. I have lost about 15 lbs. I feel like I’ve just lost interest in eating. I probably could have lost more weight if when I did eat I chose healthier options. I eat at the very most 2 times/day. Some of the side effects are… I can not drink ANYTHING carbonated. Double disgusting.

    My feet tingle sometimes (like as if they’ve fallen asleep and have pins and needles), I have some memory issues (but who doesn’t lol) and my word retrieval could be better at times. I find the benefits to outweigh the… (yep can’t find the word lol)… the side effects (for lack of a better word).

    My migraines are down to one in the last 3 months as compared to 3 a week and my weight loss is cool. I’m a happy camper:-) #topamax

    • Haley Hoile January 31, 2017, 2:36 pm

      I deal with the same thing, but only I’m not sure if I’ve lost weight or not. I’m still able to eat I guess, probably because I’m taking other medications for other things as well.

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