Does Ketamine Affect Appetite or Weight? (2026)

"Will this change my appetite?" and "Am I going to gain weight on this?" are among the most common questions I get once a patient has decided ketamine might be right for them. Sometimes the worry is about gaining weight, the way some people do on certain antidepressants. Sometimes it's the opposite: someone hoping ketamine might curb their appetite the way the GLP-1 drugs do. Both questions deserve an honest answer, and the honest answer is less dramatic than either hope or fear.

Ketamine is a treatment for depression, anxiety, PTSD, and chronic pain. It is not a weight drug in either direction. It does have some effects on appetite around the edges of a session, and it can move weight indirectly by changing mood, but it is not a tool for gaining or losing weight, and I would steer anyone away from thinking of it that way. Here's the fuller picture.

Does ketamine affect appetite?

Yes, but mostly in the short term, and mostly as a side effect of the session itself rather than a lasting change to how hungry you feel day to day.

Around a dosing session, two things can nudge appetite. The first is nausea. Sublingual racemic ketamine at antidepressant doses can produce queasiness, particularly in the first few sessions, and nobody wants to eat when they feel nauseated. The second is dissociation: during and shortly after the medicine's effects, you're inwardly focused and not thinking about food. Neither of these is an appetite-suppressing drug effect in the way people sometimes imagine. They're situational. Once the session is over and the nausea settles, appetite generally returns to baseline, and some people actually feel hungry, especially if they skipped food beforehand.

The longer-term picture is different, and it's where most of the meaningful change happens. Depression itself is one of the most powerful appetite modifiers there is. It flattens interest in food for some people and drives overeating in others. When ketamine works and mood lifts, whatever eating pattern depression had imposed tends to loosen. That's not ketamine acting on an appetite center. It's your appetite responding to feeling better.

Does ketamine cause weight gain or weight loss?

There is no strong, consistent evidence that ketamine directly causes weight gain or weight loss. The data that exist are limited and mixed, and much of what patients notice is downstream of mood rather than a direct metabolic effect.

This is worth being precise about, because it's easy to find confident claims in both directions online. In the controlled research on ketamine and esketamine for depression, weight and appetite changes are tracked as possible adverse events, but they don't emerge as a defining or consistent feature of treatment. A large Cochrane systematic review of ketamine and related glutamate modulators for depression catalogued the adverse-effect profile in detail without weight change standing out as a signature effect (Dean et al., 2021; PMID 34510411). Long-term follow-up of esketamine in treatment-resistant depression, such as the SUSTAIN-3 maintenance data, has likewise reported the tolerability picture over extended use without a dramatic weight signal dominating it (Zaki et al., 2023; PMID 37173512).

So when weight does move during a course of ketamine, the more likely explanation is indirect. Consider the two directions depression pushes people:

Melancholic depression often suppresses appetite. Food loses its appeal, meals get skipped, and weight drifts down. When this kind of depression improves, eating picks back up and some of that lost weight returns. That's a sign of recovery, not a side effect.
Atypical depression frequently does the reverse, driving carbohydrate cravings, comfort eating, and weight gain. As mood stabilizes, the emotional pull toward food eases for many people, and weight can settle lower.

The point is that ketamine's real lever on weight is mood, and mood moves weight in whichever direction your particular depression had been pushing it. There's no single "ketamine makes you gain" or "ketamine makes you lose" rule, because there's no single starting point.

Why might my appetite change on ketamine?

If your appetite does shift during treatment, it's usually one of a few understandable reasons rather than a hidden metabolic effect.

Session-day nausea and dissociation. As above, the hours around a session are the most likely time to notice reduced interest in food. This is transient and expected, and it's why we give meal-timing guidance for the day of a session.

Mood and the brain's reward circuitry. Depression blunts the reward and motivation systems that make food feel appealing. Ketamine's antidepressant effect works through glutamate signaling and neuroplasticity in exactly those circuits. As those systems come back online, the pleasure and interest in eating that depression had dulled can return. Real-world data show ketamine produces meaningful, often rapid improvement in treatment-resistant depression (Alnefeesi et al., 2022; PMID 35688035), and appetite normalization frequently rides along with that broader improvement.

Other medications and life changes. People starting ketamine are often adjusting other medications, sleeping differently, becoming more active as they feel better, or simply paying more attention to their habits. Any of these can move appetite and weight independently of the ketamine itself.

What ketamine is not is an appetite-suppressing or metabolic drug. It doesn't act on GLP-1 receptors, it doesn't slow gastric emptying to keep you full, and it has no place being used to control weight.

Is ketamine used to treat eating disorders?

Not as an approved or established treatment. There is genuine early research interest in ketamine for anorexia nervosa specifically, but it is exploratory, small-scale, and nowhere near standard care, and it is not something Tovani offers.

I want to be careful and honest here, because this is a place where hope can outrun evidence. The scientific rationale that has drawn researchers to study ketamine in anorexia is that the disorder involves glutamate and NMDA-receptor signaling, rigid thought patterns, and frequently co-occurring depression and anxiety, all areas where ketamine has plausible mechanistic relevance. Narrative reviews have laid out this rationale and the very preliminary human observations behind it (Keeler et al., 2021; PMID 34836413), and some researchers have proposed combined approaches such as ketamine paired with zinc, again on largely theoretical and early grounds (Mitchell et al., 2023; PMID 36681939).

But "there is a research rationale" is a long way from "this is a treatment you should seek." Anorexia and bulimia are serious, medically dangerous conditions that require specialized, multidisciplinary eating-disorder care, and they are not conditions we treat at Tovani. If you're struggling with an eating disorder, the right next step is an eating-disorder specialist or program, not ketamine. I mention the research only so that the honest state of it is clear, not as an invitation to pursue it off-label.

Ketamine and GLP-1 medications (Ozempic, Wegovy)

Because appetite and weight are on people's minds, GLP-1 medications come up constantly, and they deserve their own note. The short version: you can almost always do ketamine therapy while on Ozempic, Wegovy, Mounjaro, or a similar GLP-1 drug. These medications and ketamine work on entirely different systems, so there's no direct pharmacological conflict.

The one place they overlap is session day. GLP-1 drugs slow gastric emptying, ketamine can cause nausea, and food sitting in your stomach makes intra-session nausea more likely. The fix is meal timing, not stopping either medication. We walk through exactly how to handle that in our dedicated post, Ketamine Therapy With Ozempic, Wegovy, or Mounjaro, which covers the fasting window, anti-nausea options, and how to schedule sessions around your injection day.

It's also worth flagging the reverse question some patients have, which is whether a weight medication could be affecting their mood. If you've wondered about that, our companion piece Does Ozempic Cause Depression? looks at what's known about GLP-1 drugs and mood. Between those two posts, the GLP-1-and-ketamine picture is covered thoroughly, so I won't duplicate it here.

What to expect around your sessions

The practical eating guidance for ketamine has nothing to do with dieting and everything to do with comfort during dosing.

Before a session, we ask for a light meal a few hours ahead and no heavy, greasy, or very large meal beforehand. An empty-ish stomach reduces the chance of nausea when the medicine takes effect. This is standard pre-session guidance and is not about restricting calories; it's about not feeling sick during your session. Our full guide, What to Eat Before and After Ketamine Therapy, lays out specifics.

During a session, you won't be eating, and you'll have a sober support person present and physician oversight of the process. If nausea does come up, it's manageable, and for patients with a history of nausea we can plan ahead with an antiemetic.

After a session, most people ease back in with fluids and light, easily digestible food before returning to a normal meal. Some feel hungry once effects fully clear, some don't feel like eating much until later that day. Both are normal. Hydration matters more than any particular food.

If you're on a GLP-1 medication, the before-session fasting window gets extended, because those drugs keep food in the stomach longer. That's the main adjustment, and it's covered in the GLP-1 post linked above.

The honest bottom line

Ketamine is a treatment for depression, including treatment-resistant depression, as well as anxiety, PTSD, and chronic pain. It is not a weight-loss drug, not a weight-gain drug, and not a treatment for eating disorders. Around a session you may feel briefly nauseated or uninterested in food, and you may feel hungry once it wears off, but those effects are short-lived. Any lasting change in your appetite or weight during treatment is most likely the visible sign of your mood improving and your eating returning to its own natural baseline, not a direct drug effect.

If you're considering ketamine primarily to change your weight, it's the wrong tool, and I'd say so plainly in a consultation. If you're considering it for depression, anxiety, PTSD, or chronic pain, and you're wondering how it might affect your appetite along the way, the answer is: probably not much directly, possibly in a good way as you start to feel better. Either way, you'll have a physician you can ask about any change you notice.

At Tovani Health, care is physician-led telehealth with sublingual racemic ketamine, delivered with a sober support person present and physician oversight throughout. We currently serve residents of Florida and New Jersey.

See if you're a fit: Check your eligibility (about 5 minutes; FL and NJ residents)
Learn more: Ketamine for depression
Have a specific concern? Bring it to your evaluation. Appetite, weight, current medications, and past experiences are all fair game, and an honest answer that accounts for your situation is the whole point.

Benjamin Soffer, DO — Tovani Health

References

Dean RL, et al. Ketamine and other glutamate receptor modulators for depression in adults with unipolar major depressive disorder. Cochrane Database of Systematic Reviews. 2021. PMID 34510411. https://pubmed.ncbi.nlm.nih.gov/34510411/
Zaki N, et al. Long-term safety and maintenance of response with esketamine nasal spray in participants with treatment-resistant depression: interim results of the SUSTAIN-3 study. Neuropsychopharmacology. 2023. PMID 37173512. https://pubmed.ncbi.nlm.nih.gov/37173512/
Alnefeesi Y, et al. Real-world effectiveness of ketamine in treatment-resistant depression: A systematic review & meta-analysis. Journal of Psychiatric Research. 2022. PMID 35688035. https://pubmed.ncbi.nlm.nih.gov/35688035/
Keeler JL, et al. Ketamine as a Treatment for Anorexia Nervosa: A Narrative Review. Nutrients. 2021. PMID 34836413. https://pubmed.ncbi.nlm.nih.gov/34836413/
Mitchell JS, et al. Ketamine and Zinc: Treatment of Anorexia Nervosa Via Dual NMDA Receptor Modulation. CNS Drugs. 2023. PMID 36681939. https://pubmed.ncbi.nlm.nih.gov/36681939/

Does Ketamine Affect Appetite or Weight?