On a GLP-1? Here's What to Actually Eat.

GLP-1 medications work. The data on weight loss, A1c reduction, and cardiovascular outcomes is some of the strongest we've seen for any class of drug in the last twenty years.

What the prescription doesn't come with is a meal plan.

Patients leave the appointment with a pen and a pamphlet and a vague instruction to "eat better." Most of them lose weight anyway, because the medication does most of the work. But a meaningful fraction lose it the wrong way — losing muscle along with fat, ending up tired, nutrient-depleted, and frustrated by side effects that better food choices would have prevented.

This is the post I wish I had time to give every patient I prescribe a GLP-1 to.

What's actually happening when you eat less

GLP-1 receptor agonists — Ozempic, Wegovy, Mounjaro, Zepbound, and others — slow gastric emptying and dampen appetite signals in the brain. You feel full faster. You stay full longer. You think about food less.

The result is that most patients eat 20–40% fewer calories without consciously trying.

That's the mechanism. It's also where the nutrition problem starts. When you cut calories that dramatically, what you eat in those reduced calories matters far more than it did before. A diet that was passable at 2,200 calories a day can be genuinely deficient at 1,400.

The two questions that determine whether you do well on a GLP-1 are:

1. Are you getting enough protein to preserve muscle?
2. Are the calories you do eat nutrient-dense enough to cover your micronutrient needs?

Most patients aren't told to think about either one.

Protein: the single most important variable

Roughly 25–40% of the weight lost on a GLP-1 is lean mass — muscle, organ tissue, bone — not fat. That number can be pushed lower with protein and resistance training. It can also be pushed much higher if you don't pay attention.

Losing muscle isn't a cosmetic issue. It lowers your metabolic rate (which is part of why people regain weight after stopping the medication), reduces your strength and balance as you age, and disproportionately impacts older patients who don't have muscle to spare in the first place.

The general target most clinicians and researchers in this space converge on: 0.7–1.0 grams of protein per pound of goal body weight per day. For a patient targeting 160 pounds, that's 110–160 grams of protein per day.

That's a lot. Especially when your appetite has been cut in half.

The practical implication: almost every meal needs to be protein-forward. Not "include some protein." Built around it.

What that looks like in practice:

• Greek yogurt with berries — about 17g protein per cup
• Eggs — about 6g protein each
• Cottage cheese — about 25g per cup
• Chicken, turkey, fish, lean beef — roughly 25–30g per 4-oz serving
• Tofu, tempeh, edamame — about 15–20g per cup
• Lentils and beans — about 15–18g per cup cooked
• Protein powder (whey, casein, or plant-based) — about 20–25g per scoop, useful when appetite is at its lowest

The morning matters most. GLP-1s tend to suppress appetite hardest in the late afternoon and evening — many patients can barely eat dinner. If you've already had 60+ grams of protein by 2 PM, a small dinner is fine. If breakfast was coffee and lunch was a granola bar, you're already behind.

Nutrient density: making 1,400 calories count

The second issue is more subtle. When calories drop, vitamin and mineral intake drops with them — and certain deficiencies are common enough on GLP-1s that they're worth specifically planning around.

The ones I watch for:

• B12. Both metformin (which many GLP-1 patients are also on) and reduced animal protein intake can deplete it.
• Vitamin D. Already deficient in most American adults. Doesn't get better when you eat less.
• Iron. Especially relevant for premenopausal women; red meat consumption tends to drop on these medications.
• Calcium. Inadequate dairy intake plus reduced absorption can quietly add up.
• Electrolytes — potassium, magnesium, sodium. Easily depleted when you're not eating much, and the symptoms (fatigue, brain fog, leg cramps) are often blamed on the medication when food is the actual cause.

The fix isn't a multivitamin. The fix is choosing the small number of foods you do eat with intent. Salmon, sardines, leafy greens, eggs, dairy, beans, nuts, seeds, and colorful vegetables cover most of the gaps. Bread, rice, pasta, and processed snacks — even in moderation — crowd out the foods that don't.

Side effects you can eat your way out of (mostly)

The most common side effects — nausea, constipation, reflux, early satiety — are food-modifiable for most patients.

Nausea. Worse with high-fat meals, large portions, and eating quickly. Smaller portions, lower-fat meals, and slowing down at the table help. Cold foods are often better tolerated than hot ones; protein shakes and yogurt are reliable when nothing else sounds appetizing.

Constipation. Almost universal at some point. Driven by reduced food volume, lower fiber intake, and dehydration. The fix is mechanical: more fluid (aim for 80–100 oz per day), more fiber from vegetables and fruit, and movement. Magnesium glycinate at night helps a meaningful fraction of patients. Talk to your doctor before adding supplements.

Reflux and heartburn. Slowed gastric emptying means food sits longer. Lying down too soon after eating, large meals, alcohol, coffee, and high-fat meals all make it worse. Eat earlier, eat smaller, stay upright for a couple of hours after.

Sulfur burps and overall GI misery. Often tied to specific trigger foods: eggs, red meat, cruciferous vegetables, and protein bars with sugar alcohols. If you're getting sulfur burps, the fix is usually identifying which food triggers them for you — it's individual.

The pattern across all of these: smaller portions, more frequent meals, lower fat at any single meal, and high fluid intake. That's most of the side-effect playbook.

Foods to actually limit

Some foods do worse on a GLP-1 than they would otherwise:

• Fried, greasy, or very fatty foods. Slowed gastric emptying makes the discomfort much worse than it would have been pre-medication.
• Alcohol. Many patients report a dramatic drop in alcohol tolerance — both the desire for it and the body's response. A glass of wine on a GLP-1 can hit like three.
• Sugary drinks and refined carbs. Calories you didn't need, displacing protein and nutrients you do.
• Ultra-processed snacks. They're easy to graze on when nothing else sounds good — and they're exactly the wrong choice for the small calorie budget.

You don't need to eliminate any of these forever. You do need to know they're working against the medication, not with it.

Thinking about the off-ramp

Most patients will, at some point, come off their GLP-1 — for cost, side effects, supply issues, or because they've reached a goal. The data on what happens next isn't reassuring: in the major trials, patients regain about two-thirds of the weight they lost within a year of stopping.

The patients who hold their loss best have two things in common: they used the time on the medication to build sustainable habits, and they preserved muscle while losing weight. Both come down to nutrition and resistance training.

Translation: the meal pattern you build during the medication is the meal pattern you'll need after it. Treating the prescription as a temporary fix without changing how you eat is the most reliable way to be back where you started in 18 months.

The honest summary

GLP-1s are one of the most effective tools in medicine for weight loss and metabolic disease. They're not a substitute for nutrition — they're a window of opportunity that nutrition either capitalizes on or wastes.

What to eat on a GLP-1 isn't complicated, but it does have to be deliberate:

• Build every meal around protein. Aim for 0.7–1.0g per pound of goal weight, daily.
• Make your reduced calories count. Whole foods, colorful plates, dairy and eggs and fish over processed snacks.
• Hydrate aggressively. Most side effects are easier to manage when you're not also dehydrated.
• Limit fried foods, alcohol, and ultra-processed carbs — not on principle, but because they make the side effects worse and crowd out the nutrients you need.
• Use the medication window to build the habits that will hold the loss after.

Most of this isn't in any patient handout I've seen. It also isn't something a 15-minute appointment can teach. That's why we built Rapha to do it instead.

You enter your medication, your weight, your goals, and your other conditions. Rapha builds you a meal plan that hits your protein targets, accounts for the foods that worsen side effects, and stays specific enough that you can actually cook it.

The medication does the appetite suppression. Your meals do everything else.

Physician-Founded · Free to Start

Your numbers deserve a plan built for them.

Most nutrition advice ignores your actual lab values. Rapha doesn't. Enter your A1c, LDL, diagnoses, and get a meal plan grounded in clinical guidelines — free.

Get my free plan

No credit card. No subscription required to start.

---

Cole Phillips, MD, MBA, is a practicing primary care physician and the founder of Rapha. This post is informational and does not constitute medical advice. Do not start, stop, or change a GLP-1 medication based on anything written here. If you are experiencing severe side effects or rapid unintended weight loss, contact your prescribing physician.