The short answer
More than you are probably eating. The baseline RDA for adults is 0.8 grams per kilogram of body weight a day; during rapid weight loss the obesity-medicine literature discusses higher intakes, up to around 1.6 grams per kilogram, to protect muscle. Ask your prescriber for your number, then spread it across small meals rather than one large one.
At GLP-1 SOS we hear this every week, usually from someone who has just realized dinner was four bites of chicken. Here is what the published guidance says, and how to get there on a stomach that fills fast.
Published numbers
The protein figures people ask about
0.8 g/kg
adult RDA from the Dietary Reference Intakes, set for a stable weight
0.8 to 1.6 g/kg
range proposed during GLP-1 weight loss, borrowed from bariatric guidance
30 to 40%
estimated share of weight lost that may be fat-free mass
Sources: Dietary Reference Intakes, National Academies, 2005; International Journal of Obesity, 2025.
What is actually happening
When you lose weight fast, you do not lose only fat. Muscle is expensive tissue to keep, so some of it goes with the fat. The Wegovy and Zepbound prescribing information both state that the medication lowers body weight with greater fat mass loss than lean mass loss. Lean mass still falls, though: a 2025 review in the International Journal of Obesity estimates that 30 to 40 percent of the weight lost on these medications may come from fat-free mass, which includes muscle, water and bone.
Lab note
Muscle is expensive tissue. Feed it, or the body sells it.
Protein is the lever. Muscle is built and repaired from amino acids, and when protein intake drops the body has less to rebuild with. On a GLP-1 that drop happens quietly: appetite falls, meals shrink, meat feels heavy, and intake can halve without anyone noticing. The Dietary Reference Intakes set the adult RDA at 0.8 grams per kilogram of body weight a day, the amount that holds body protein steady in a healthy adult at a stable weight. It was never designed for someone losing weight quickly.
That is why the obesity-medicine literature discusses higher targets. The same 2025 review describes proposed ranges of 0.8 to 1.6 grams per kilogram a day, or 80 to 120 grams a day, borrowed from bariatric surgery guidance, while noting that trials specific to these medications are still lacking. A 2025 joint advisory from four US obesity and nutrition organizations lists adequate protein with strength training as a core priority on GLP-1 therapy. Where you sit in that range depends on your weight, kidneys and age, and that is a prescriber decision.
Timing matters as much as the total. A slowed stomach handles a large protein load badly: it sits for hours, ferments, and comes back as sulfur burps, while muscle does better with a steady supply than with one large delivery. Small protein portions, first on the plate at each meal, suit both.
Three ways to get there
Same grams, different stomach
Small portions
Four or five times a day
Muscle: Steady supply all day
Stomach: Light loads it can clear
Sulfur burps: Least likely
Effort: Needs planning
Usual choice
Shakes
Fill the gap on low days
Muscle: Good when it adds, not replaces
Stomach: Easy when sipped slowly
Sulfur burps: Low with clear or low-fat
Effort: Easiest
One big meal
Protein at dinner only
Muscle: Long gaps without supply
Stomach: Sits for hours on a slow gut
Sulfur burps: Most likely
Effort: Familiar, but backfires
What to do
- Get your number from your prescriber. Divide your weight in pounds by 2.2 to get kilograms, then multiply by the target they give you. The obesity literature puts many adults between 80 and 120 grams a day.
- Protein first, every meal. Eat the protein portion before anything else, while the stomach has room and appetite is highest. Vegetables and starch come after.
- Split it into small portions. A palm-sized serving four or five times a day rather than a steak at dinner. A slowed stomach clears small loads, and muscle uses a steady supply.
- Choose protein that sits light. Eggs, Greek yogurt, cottage cheese, white fish, chicken, tofu and lentils. Fried or fatty protein slows the stomach further and lingers.
- Use shakes to fill gaps. A clear or low-fat protein shake sipped over an hour on a low-appetite day is easier than forcing a meal. It tops up meals; it does not replace them.
- Lift something twice a week. Protein protects muscle only when the muscle is asked to work. Bodyweight squats, resistance bands or light weights, starting small and building.
- Watch for sulfur burps. If a big protein meal comes back as rotten-egg burps, the stomach could not clear it. Halve the portion and spread it out rather than dropping protein for the day.
From our support desk at GLP-1 SOS
If you wrote to us tonight asking how much protein, here is what we would say.
We would start with your weight. The adult RDA is 0.8 grams per kilogram, and the obesity literature discusses up to about 1.6 during fast weight loss, so for most people the answer lands somewhere between those two lines; your prescriber picks the point based on your weight, age and kidneys. Then we would talk about the stomach, because a slowed stomach cannot take a steak. Eat protein first at four or five small meals, choose eggs, yogurt, fish and lentils over fried or fatty options, and sip a shake on the days when eating is hard. Add two short strength sessions a week. No supplement replaces any of that.
We answer real questions from real people every day. Write to us if yours is not here.
Protein on a slow stomach
What sits light and what sits heavy
Sits light
- Eggs and egg whites
- Greek yogurt and cottage cheese
- White fish and shrimp
- Chicken or turkey breast
- Tofu, lentils and beans in small amounts
- Clear or low-fat protein shakes
Sits heavy
- Fried chicken or fish
- Fatty steak, sausage and bacon
- Creamy, high-fat shakes
- A whole protein bar in two bites
- Large protein portions late at night
- Cheese-heavy dishes
Fat slows the stomach further. Lean protein clears faster and burps less.
When to call your doctor
Call your prescriber the same day if:
- You cannot keep food or liquids down
- You feel faint when you stand
- You are vomiting
- You have severe abdominal pain
- Your legs feel weak enough to change how you climb stairs or stand from a chair
- You are losing weight much faster than your prescriber expected
- You have kidney disease and are raising your protein
- Sulfur burps come with pain or fever
Eating less is expected. Losing strength is not.
From the people behind the Lab
You do not have to figure this out alone.
GLP-1 SOS is the daily companion made for life on a GLP-1. Plain answers like this one, a support team that replies to real questions from real people, and daily formulas like GLP-1 SOS Daily Gut Relief, designed around the side effects that come with the medication. The GLP-1 Lab is our free education arm: no login, no paywall, no hype. Side effects are part of the road. Suffering through them is not.
Questions people also ask
Is 100 grams of protein a day enough on a GLP-1?
For many adults it lands inside the range the obesity literature discusses, which describes absolute amounts of 80 to 120 grams a day or 0.8 to 1.6 grams per kilogram. Whether 100 is enough for you depends on your weight: at 90 kilograms it is about 1.1 grams per kilogram, at 60 kilograms about 1.7. Ask your prescriber which figure fits you, especially if you have kidney disease.
Do I need protein shakes on Ozempic or Wegovy?
Not necessarily, but they are useful on days when eating is hard. A shake is protein you can sip slowly past a stomach that does not want a plate of food. Use it to top up, not to replace meals, because whole food carries the iron, zinc and fiber a shake usually does not. Choose low-fat or clear options; creamy, high-fat shakes sit heavy on a slow stomach.
Why do I get sulfur burps after eating protein on a GLP-1?
Because the protein stayed in the stomach too long. When a large protein meal sits on a slowed stomach, bacteria ferment it, and protein rich in sulfur compounds, such as eggs and meat, produces the rotten-egg smell. Smaller portions, spread across the day, with less fat, usually stop it. Sulfur burps with pain, vomiting or fever need a same-day call.
Will I lose muscle on Mounjaro or Zepbound?
Some lean mass loss is expected with any fast weight loss, and the labels for both Zepbound and Wegovy note that fat mass loss is greater than lean mass loss. The 2025 obesity literature estimates 30 to 40 percent of weight lost may be fat-free mass. Adequate protein spread through the day and two strength sessions a week are the two levers you control.
Sources (6)
- Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. National Academies Press, 2005.
- Bridging the nutrition guidance gap for GLP-1 receptor agonist therapy assisted weight loss: lessons from bariatric surgery. International Journal of Obesity, 2025.
- Nutritional priorities to support GLP-1 therapy for obesity: a joint advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association, and The Obesity Society. Obesity, 2025.
- Wegovy (semaglutide) injection, Prescribing Information. Novo Nordisk / FDA, revised February 2026.
- Zepbound (tirzepatide) injection, Prescribing Information. Eli Lilly, revised August 2026.
- Dietary Guidelines for Americans, 2020-2025. US Department of Agriculture and US Department of Health and Human Services, December 2020.
Reviewed by the GLP-1 SOS editorial team · Education, not medical advice · Talk to your prescriber about your dose and your symptoms.