What to eat on a GLP-1

On a GLP-1 receptor agonist most people eat a lot less without trying. The joint advisory below cites observed calorie reductions of 16 to 39 percent. That is the point of the drug, and also the problem: eat a third less of a typical diet and you get a third less protein, fibre, iron and calcium along with it. What you eat matters more on these drugs, not less.

The joint advisory

In May 2025 the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association and The Obesity Society published a joint advisory, Nutritional priorities to support GLP-1 therapy for obesity, in four journals at once. It is consensus guidance from an expert panel rather than a new trial, and it is the most complete statement on the subject so far. Its eight priorities run from how treatment is started to sleep and stress. The food parts are below.

Protein first

The advisory notes the adult RDA of 0.8 g of protein per kilogram of body weight a day and says higher targets, such as 1.2 to 1.6 g/kg, have been proposed during active weight loss. Because actual body weight overstates needs in people with obesity, it offers a simpler alternative: an absolute target of 80 to 120 g a day. The new US Dietary Guidelines, released in January 2026, set the same 1.2 to 1.6 g/kg range for the general population.

The practical advice is to eat the protein part of a meal first, while appetite lasts, and to favour compact sources: fish, eggs, Greek yoghurt, cottage cheese, tofu, lentils and beans, nuts and nut butters. Shakes count. The protein guide has the numbers per food and per meal.

The advisory is direct that protein alone is not enough: without structured strength training, it is unlikely to preserve muscle. It recommends strength training at least three times a week plus at least 150 minutes of moderate aerobic exercise. The trial evidence backs the pairing: in the S-LITE trial (NEJM, 2021), adults who combined liraglutide with an exercise programme for a year kept off 9.5 kg more than placebo and cut body fat percentage about twice as much as with either alone. See exercise to keep muscle.

What the advisory says to eat and to limit

Eating around the side effects

Nausea is the most common gut side effect and, the advisory notes, often comes in the morning or after long stretches without food. Its suggestions:

• Small meals every three to four hours, starting with a small breakfast, rather than skipping meals and then eating a large one. Vomiting is more likely after a large meal.
• Go easy on fatty and high-fibre foods in the first few days of a new dose. Both slow the stomach further.
• Ginger or peppermint tea may help.
• Fluids through the day. Dehydration from vomiting or diarrhoea is how the kidney injury on the drug labels happens. See hydration and electrolytes.
• Constipation: build up fibre gradually (prunes and other dried fruit are named), with fluids. Fibre supplements can help. The fibre guide covers how much.
• When food is unappealing: smoothies, protein drinks, yoghurt, cottage cheese and soups are often easier than red meat, cold cuts or hard cheese.

Food changes help most people, but not all. If nausea at week four of a dose step is as bad as week one, that is a dose conversation; the nausea page covers it, and the side effects page lists the symptoms that need a same-day call.

Micronutrients

At lower intakes, especially below about 1,200 kcal a day for women and 1,800 for men, it gets hard to meet vitamin and mineral needs from food. The advisory names iron, calcium, magnesium, zinc and vitamins A, D, E, K, B1, B12 and C as nutrients of concern, and suggests considering vitamin D, calcium, B12 or a multivitamin where needed. Fatigue beyond what you would expect, heavy hair loss, flaky or itchy skin, poor wound healing and easy bruising are signs worth raising. The micronutrients guide goes further.

Diet patterns

The advisory does not require a named diet. A ketogenic or very-low-carbohydrate diet can work for some people, with two cautions: build it on minimally processed, high-fibre foods, and if you have diabetes, combining keto with a GLP-1 can raise the risk of ketoacidosis and low blood sugar, so talk to your prescriber first. The same goes for any condition that changes what you can eat.

A day on a plate

An example day near 1,600 kcal and 115 g of protein: Greek yoghurt with berries and oats; chicken, quinoa and salad with olive oil; salmon, a baked potato and broccoli; an apple and a handful of almonds. The sample week has seven days of these with approximate macros.

What to log

Three numbers do most of the work: protein grams a day, how you felt after meals in the days after a dose, and weight once or twice a week. In Peptide AI, meals and protein go in nutrition tracking, the shot goes in the dose log, and side effects sit on the same timeline, so you can see whether the bad days follow the dose, the big meal or both. The body scanner is there if you want to watch body composition rather than weight alone.