Eating when your appetite is low

Why appetite drops

The Wegovy® label says semaglutide decreases calorie intake and that this is likely mediated by appetite, with GLP-1 receptors present in brain areas that regulate food intake ^[1]. The Mounjaro® label says tirzepatide decreases food intake, and the labels describe both medicines as slowing how quickly the stomach empties ^[1][3].

In daily life this can mean hunger arrives later, fullness arrives sooner and a usual portion feels like too much. That is an expected effect of the medicine, not in itself a sign that something has gone wrong. What changes is the margin: when you eat less, what you do eat carries more of the load.

What the labels pair the medicine with

Wegovy® and Zepbound® are approved for weight reduction together with a reduced-calorie diet and increased physical activity ^[1][2]. In the main Zepbound® trials, everyone, including the placebo groups, was taught a reduced-calorie diet, counselled on activity and given help with behaviour change ^[2].

The labels do not list foods to eat or avoid. MedlinePlus, the patient site of the US National Library of Medicine, asks people on semaglutide to follow the diet and exercise advice of their doctor or dietitian, and people on tirzepatide to keep to their normal diet unless their doctor says otherwise ^[8][9]. NIDDK adds that weight management medicines do not replace healthy eating and work best as part of a lifestyle programme ^[10].

When eating less turns into eating too little

The US labels reviewed here have no section on malnutrition. The Canadian product monographs for tirzepatide do. The Mounjaro® monograph reports malnutrition in people taking the medicine, including severe, serious and fatal cases, and says nutritional guidance and supplementation should be considered, with stopping treatment considered when malnutrition is severe or persistent ^[5]. The Zepbound® monograph spells out the risks: too few vitamins and minerals, too little protein and a body weight that falls too low ^[6].

The patient section of the Zepbound® monograph describes how malnutrition can show: losing weight, weakness, feeling faint, tiredness, dry skin, irritability and trouble paying attention. It lists it among the serious side effects to raise with your healthcare professional in all cases, and says your healthcare professional may give you nutrition guidance or suggest vitamins or supplements ^[6].

What studies say people actually eat

Less is known than you might expect. A 2024 narrative review found that studies of people on GLP-1 or dual GIP/GLP-1 medicines measured a clear drop in total intake, but few looked at what the diet was made of ^[13]. A 2025 scoping review of 129 randomised trials of liraglutide, semaglutide and tirzepatide found that only 36 recorded diet data and only 10 reported dietary outcomes ^[14].

One of the few direct looks is a 2025 cross-sectional study of 69 adults who had been on a GLP-1 medicine for at least a month. Their three-day food records showed average intakes below reference values for fibre, calcium, iron, magnesium, potassium, choline and vitamins A, C, D and E, and fewer servings of fruit, vegetables, grains and dairy than recommended ^[12]. The study was small and relied on online questionnaires and self-reported records, and its authors work for a supplement retailer, so it shows a possible pattern rather than a rule.

What to put first when portions are small

Neither the labels nor the guidelines give a plan for people on these medicines, but both of the general sources below agree on what matters most when there is little room on the plate:

• Protein foods at every meal, from a mix of animal and plant sources such as eggs, poultry, seafood, meat, beans, lentils, nuts, seeds and soy ^[7]. The 2025 advisory suggests eating the protein part of a meal first so it is not left behind ^[11].
• Vegetables and fruits through the day, ideally whole; frozen, dried or canned options with little or no added sugar also count ^[7].
• Whole grains rich in fibre, with far less highly processed, refined carbohydrate ^[7].
• Fewer highly processed foods, added sugars and sugary drinks; water and unsweetened drinks instead ^[7].
• Small, frequent meals when hunger and interest in food are low, which the advisory describes as a possible help ^[11].
• If you have a chronic disease, the guidelines ask you to talk with your health care professional about adapting them, and the advisory says supplements can be considered for nutrients at risk, tailored to each person ^[7][11].

Fluids still count

Eating less also means taking in less of the water that food contains. The Ozempic® and Wegovy® Medication Guides link fluid lost through vomiting or diarrhea to possible kidney problems and say drinking fluids helps lower the chance of dehydration ^[1][4]. The Dietary Guidelines point to water and unsweetened drinks ^[7]. Our article on hydration covers the label wording brand by brand.

Other reasons appetite can fall

A GLP-1 medicine is not the only thing that can dull appetite. MedlinePlus lists illness in general, sadness, depression or grief, chronic liver or kidney disease, an underactive thyroid, early pregnancy and some other medicines among the causes, and notes that in older adults often no physical cause is found ^[15].

It also asks people to seek medical help when a poor appetite comes with signs of depression, alcohol or drug use, or an eating disorder ^[15]. If your appetite fell before you started the medicine, or has not followed the usual pattern of dose changes, that is worth telling your clinician.

Signs that are more than low appetite

• Severe stomach pain that will not go away, with or without vomiting, sometimes felt through to the back: the Medication Guides list it under pancreatitis and ask you to stop the medicine and call your provider right away ^[1][4].
• Pain in the upper stomach, fever, yellowing of the skin or eyes, or clay-coloured stools, which the Medication Guides list under gallbladder problems ^[1][4].
• Weight loss with weakness, feeling faint, tiredness or trouble concentrating, which the Canadian Zepbound® leaflet links to malnutrition ^[6].
• If you also use insulin or a sulfonylurea, hunger, shakiness, sweating and dizziness can be signs of low blood sugar ^[4].

Ozempic® and Wegovy® are registered trademarks of Novo Nordisk A/S. Mounjaro® and Zepbound® are registered trademarks of Eli Lilly and Company. PepLabo is not affiliated with or endorsed by Novo Nordisk or Eli Lilly and Company.

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