Decreased appetite in each data set
The US label’s Table 1 comes from SURPASS-1 and SURPASS-5, placebo-controlled trials in 718 adults with type 2 diabetes; decreased appetite is its third row, after nausea and diarrhea [1]. Health Canada’s version gives the decimals for that pool and a second, broader set of seven phase 3 studies in which 5,119 people received tirzepatide [4]. In SURPASS-CVOT, the long trial in adults with diabetes and established heart disease, 17% on Mounjaro® reported decreased appetite; the comparison was dulaglutide, with no figure given for it [1].
| Data set | Placebo | 5 mg | 10 mg | 15 mg |
|---|---|---|---|---|
| US: adult placebo-controlled pool [1] | 1% | 5% | 10% | 11% |
| Canada: same pool, unrounded [4] | 1.3% | 5.5% | 9.6% | 11.2% |
| Canada: 7 phase 3 trials [4] | No placebo column | 7.8% | 9.8% | 11.7% |
A row that climbs with dose
Few people on placebo reported eating less, so the medicine stands out clearly here, and the rate rises from 5 mg to 15 mg in both the US and Canadian pools [1][4]. These are shares of people who reported the reaction at least once, not a measure of how much less they ate. A meta-analysis of tirzepatide in type 2 diabetes found decreased appetite more frequent than with placebo and insulin at all doses, with a conclusive difference against placebo, and more frequent than with GLP-1 receptor agonists at 5 mg and 10 mg [6].
The European information lists decreased appetite as a side effect for people with type 2 diabetes: “very common” in SURPASS-CVOT and “common” in the other adult and pediatric diabetes trials [3]. For children aged 10 and older, the US label does not name appetite among the reactions that were more frequent than in adults [1].
Side effect or intended effect?
It depends on where you are and why you take it. In the US, Mounjaro® is approved to improve blood sugar in type 2 diabetes in adults and children aged 10 and older, and to reduce major cardiovascular events in adults with type 2 diabetes at high risk [1]. Canada approves it for type 2 diabetes [4]. In the EU, Mounjaro® is also authorised for weight management in adults with obesity, or with overweight and a weight-related condition, and its package leaflet explains that it influences appetite regulation, which may help you eat less and reduce body weight [3].
Whatever the indication, the US label states that tirzepatide lowers food intake and body weight in people with type 2 diabetes [1]. Reduced appetite only becomes a concern when it leads to too little food, too little fluid, low blood sugar or a symptom that bothers you.
How tirzepatide reduces hunger
What the label supports: tirzepatide activates receptors for two gut hormones, GIP and GLP-1, reduces food intake and delays stomach emptying, most strongly after the first dose [1]. The label does not explain the appetite effect in more detail.
What a study measured: in a 28-week randomised study in people with type 2 diabetes, tirzepatide 15 mg and semaglutide 1 mg both reduced appetite scores compared with placebo, and their effects on appetite and on energy intake at a test lunch did not differ. Tirzepatide led to more weight and fat loss, and the authors concluded that differences in intake at that meal could not fully explain why; other factors such as energy use need more study [5].
General background: MedlinePlus notes that almost any illness can reduce appetite, and that emotions such as sadness or grief can too [8].
When eating less goes too far
Canada’s monograph lists malnutrition among Mounjaro®’s serious adverse reactions, describes severe, serious and fatal cases, and advises considering nutritional guidance and supplements, and stopping treatment for severe or persistent malnutrition [4]. Its patient information describes the risk as low vitamin, mineral or protein levels and low body weight, and asks people with very low food intake or poor nutrition to say so before starting [4].
A 2026 review of observational studies in GLP-1 medicine users, including tirzepatide, found vitamin D deficiency, lower iron stores and growing thiamine and vitamin B12 shortfalls over time, but notes that it cannot prove the medicines caused them [7]. MedlinePlus lists tiredness, dizziness and weight loss as general signs of malnutrition [9].
Eating less with insulin or a sulfonylurea
Used without insulin or a sulfonylurea, Mounjaro® rarely caused low blood sugar in trials; in the US monotherapy trial, no one on it had glucose below 54 mg/dL [1]. The label warns, however, that the risk rises, including severe episodes, when it is combined with insulin or a sulfonylurea, and that doses of those medicines may need lowering [1]. The NIH adds that skipping or delaying meals, or eating too few carbohydrates, can push blood glucose too low in people on these medicines [10].
So a sharp drop in how much you eat is information your diabetes team needs, especially in the first weeks and after dose steps. The Medication Guide asks you to discuss low blood sugar, and what to do about it, with your provider before the first dose [2].
Other reasons for a poor appetite
MedlinePlus lists many causes of decreased appetite besides medicines: depression, grief, early pregnancy, an underactive thyroid, chronic kidney or liver disease, heart failure, some cancers and certain other medicines, such as antibiotics, codeine and morphine [8]. It advises seeking medical help when appetite loss comes with signs of depression, alcohol or drug use, or an eating disorder [8]. Canada’s monograph also asks for monitoring of mood changes and thoughts of self-harm in people taking Mounjaro® [4].
MedlinePlus’s usual threshold for unexplained weight loss does not fit neatly here, because weight loss is expected on tirzepatide; whether yours is appropriate is for your prescriber to judge [8].
What may help, and what to tell your prescriber
MedlinePlus suggests several small meals or nourishing snacks through the day when appetite is low, and keeping a record of what you eat and drink for at least a day to show your provider [8]. Canada’s patient information says your prescriber may give nutrition guidance or recommend vitamins or supplements [4]. Drinking enough also matters, because the labels link fluid loss to kidney problems [2].
Bring notes on how much and how often you are eating, any weight change, whether nausea or fullness is the main barrier, and any dizziness, tiredness or low readings if you check your glucose. Changes to your dose or other medicines are your prescriber’s decision.
Mounjaro® is a registered trademark of Eli Lilly and Company. PepLabo is not affiliated with or endorsed by Eli Lilly and Company.
When to get help
| Sign | Who to contact | How fast | Source |
|---|---|---|---|
| Confusion, a seizure or passing out, especially if you use insulin or a sulfonylurea | Emergency services; this may be severe low blood sugar | Emergency | NIH [10]; Canadian patient information [4] |
| Thoughts of harming yourself, or new or worse changes in mood | Your healthcare professional right away; emergency services in a crisis | Emergency | Canadian patient information [4] |
| Shakiness, sweating, hunger, a fast heartbeat or dizziness while eating little | Check and treat as you were taught, then call your diabetes team | Today | Medication Guide [2]; NIH [10] |
| Eating or drinking so little that nausea, vomiting or diarrhea will not settle | Your healthcare provider, right away | Today | Medication Guide [2] |
| Ongoing tiredness, dizziness or low body weight with very small meals | Your prescriber, to check your nutrition | At your next appointment | Canadian monograph [4]; MedlinePlus [9] |
| Reduced appetite that bothers you or does not settle | Your prescriber | At your next appointment | Medication Guide [2] |
