How many calories should you eat on a GLP-1?

On a GLP-1 medicine, hunger often goes quiet, and it can be hard to tell whether you’re eating enough. This guide explains how calorie needs are estimated, the lower limits guidelines use, and why what’s on the plate matters as much as the total. Your prescriber or a registered dietitian can set a number for your own health, and any dose questions are for your prescriber.

How many calories should I eat on a GLP-1?

There’s no single number, because your needs depend on your age, sex, height, weight and how active you are.

The Dietary Guidelines for Americans say daily calorie needs vary with all of these, plus whether you’re trying to lose, maintain or gain weight. For adults keeping their weight steady, their estimates range from 1,600 to 2,400 calories a day for women and 2,000 to 3,000 for men. Needs generally go down with age.

On a GLP-1, the usual approach is to estimate what you burn, set a gentle target a bit below that, and never go under a safe floor. Try the calorie calculator to see your own estimate.

How do you work out your daily calorie needs?

Most calculators start with the Mifflin–St Jeor equation for the energy you burn at rest, then multiply by an activity factor.

The equation, published in 1990, uses your weight, height, age and sex. A 2005 systematic review for the American Dietetic Association compared the common equations. It found Mifflin–St Jeor the most reliable, estimating resting needs within 10% of measured values for more people than the others.

It’s still an estimate. The same review warns of noteworthy errors for individuals, and notes older adults and some ethnic groups were underrepresented in the research. Treat your number as a starting point and adjust it with your care team.

What’s the lowest number of calories I should eat?

About 1,200 calories a day for women and 1,800 for men, according to the most recent guidance for people on a GLP-1.

The 2025 joint advisory from ACLM, ASN, OMA and TOS says intake below about 1,200 calories a day for women and 1,800 for men makes it hard to get enough vitamins and minerals. Appetite on a GLP-1 can drop a lot, so these numbers are worth keeping in mind on low days.

Older guidance set the bar lower for men. The 2013 guideline from the American Heart Association, American College of Cardiology and The Obesity Society (AHA/ACC/TOS) suggested 1,200 to 1,500 calories a day for women and 1,500 to 1,800 for men for a reduced-calorie diet, or a daily deficit of 500 to 750 calories. Imi follows the newer advisory.

What happens if I eat too little on a GLP-1?

Eating too little can leave you short on nutrients and protein, which can show up as tiredness, hair loss or muscle weakness.

The advisory notes that people on GLP-1 medicines often eat far less than before. It lists signs of nutrient deficiency, including fatigue beyond what you’d expect, excessive hair loss, flaky or itchy skin, muscle weakness, poor wound healing and unusual bruising. It also says low protein from a smaller appetite may contribute to muscle loss.

Stomach side effects can make this harder. The Wegovy label says vomiting and diarrhea can lead to dehydration, so fluids count too.

On days when eating feels hard, small meals and snacks spread through the day can help.

Should I focus on calories or protein?

Protein and nutrient-dense food come first, with calories as a guardrail rather than a target to push lower.

The advisory says enough protein should be a priority to help preserve muscle mass and bone density. It suggests 1.2 to 1.6 grams per kilogram of body weight a day while losing weight. It also stresses making the most of nutrients within a smaller amount of food:

• Protein at every meal. Eggs, Greek yogurt, fish, chicken, tofu, beans and lentils.
• Plenty of plants. Vegetables, fruits, whole grains, nuts and seeds.
• Fewer empty extras. The advisory suggests limiting refined starches and sugars, sugar-sweetened drinks and most fast food.

Find your number with the protein calculator, and read protein on a GLP-1 for ideas.

Do I need to count calories on a GLP-1?

Not necessarily, but a rough check can help you notice if you’re eating far less than you need.

Some people find a daily target useful as a floor to reach, not a ceiling. Others prefer to watch protein and let calories follow. Either way, the aim is steady, nourishing meals. If your appetite is very low, small meals and snacks through the day can add up.

How does Imi set your calorie target?

Imi estimates your daily burn with Mifflin–St Jeor, sets a gentle target, and never goes below the floor.

• Safe floors. Imi never sets a target below 1,200 calories a day for women or 1,800 for men, following the 2025 advisory.
• Gentle pace. The deficit is capped at 25% below your estimated daily burn.
• Protein from your weight. Your protein target is worked out from your body weight, so it fits you.

You can read the details on how we choose numbers.

How does Imi help?

Imi turns the numbers into meals you’ll want to eat.

• Meals around your targets. Imi plans your week from your saved recipes around your calorie and protein targets.
• Protein and water first. Your targets sit at the top of every day.
• Easy logging. Log meals by photo, barcode, text or voice.
• Gentler days. Lighter meals are planned after a dose or when you log nausea.

Imi helps with food. Your prescriber handles your medication. For the bigger picture, read eating well on a GLP-1 or visit the GLP-1 hub.

Wegovy is a trademark of Novo Nordisk A/S. Imi isn’t affiliated with Novo Nordisk A/S.