Eating when you have no appetite

Most people start a GLP-1 having spent years trying to eat less. Within a few weeks the problem inverts. Appetite drops, meals shrink, and the risk becomes under-eating in specific ways: too little protein, too little fluid, and food choices that make nausea worse. This page is the fix, kept short because you will not feel like reading it on a bad day.

The one rule

Protein first, fluids on a schedule, everything else after. If you only manage half a plate, the half you eat should be the protein.

Why protein

The weight you lose is a mix of fat and lean tissue. The nutrition literature on weight loss puts protein intakes of about 1.2 to 1.6 grams per kilogram of body weight per day as the range associated with better preservation of lean mass and greater satiety during a deficit (Leidy et al. 2015, PubMed 25926512). That is not a label figure and it is not a prescription; it is the range most clinicians use as a starting point. For a 100 kg person it is 120 to 160 grams a day, which is hard to reach on a small appetite without planning. The protein target calculator does the arithmetic and splits it across meals; the Weight Loss on GLP-1s site covers resistance training, which is the other half of keeping muscle.

Practical sources when you can only eat a little: eggs, Greek yogurt, cottage cheese, fish, chicken, tofu, lentils, a protein shake when nothing solid appeals. Liquid protein counts, and on shot days it may be all you want.

Shot-day food

Novo Nordisk's own patient guidance for nausea is sensible and simple: eat bland, low-fat foods (crackers, toast, rice), eat foods that contain water (soups, gelatin), do not lie down after eating, get fresh air, and eat slowly and stop when full. Add to that what the mechanism predicts: because stomach emptying is slower, large meals and high-fat meals sit longer and are more likely to come back up. Small plates, more often, on the two or three days after each injection, then normal size as the week goes on.

What tends to trigger nausea

Reports are consistent enough across people to list: large portions, fried or greasy food, very sweet food, alcohol, eating fast, eating late and lying down, and strong smells. None of these is a rule from a label; they are the patterns that follow from delayed gastric emptying. Keep your own list in the weekly log; by week 8 you will know yours.

Constipation

The other end of the same mechanism. Constipation is reported in 24% of people on Wegovy versus 11% on placebo, and 11 to 17% on Zepbound versus 5% (label section 6.1). Fluids first (hydration), then fibre from vegetables, fruit, oats, beans and seeds, then movement. If those are not enough, ask your prescriber or pharmacist about an over-the-counter option rather than guessing. Severe constipation with abdominal pain, bloating and vomiting is on the call list.

The number on the box

The trials paired the drug with a 500 kcal per day deficit and 150 minutes of weekly activity (STEP 1, PubMed 33567185; SURMOUNT-1 used the same programme), and the labels indicate the drug in combination with a reduced-calorie diet and increased physical activity. In practice the appetite effect often produces a larger deficit than that on its own, which is why the advice on this page is about eating enough of the right things rather than eating less.

When under-eating becomes a problem

Persistent dizziness on standing, dark urine, headaches, fatigue that does not lift, or losing weight much faster than the trial averages are all reasons to talk to your prescriber; the label's acute kidney injury warning is about dehydration from exactly these circumstances. Vomiting that stops you keeping fluids down is a same-day call.

Short version for the fridge door

• Protein at every meal, first bite.
• Water or an electrolyte drink by the clock, not by thirst.
• Small, bland, low-fat on the two days after a shot.
• Do not lie down after eating.
• Fibre and fluids for constipation; ask before adding anything else.
• Call if you cannot keep fluids down.