How to Prevent Muscle Loss on GLP-1 Medications

The major trials measured body composition with DXA scans, the same X-ray method used for bone density. Here is what they found.

In STEP 1, people lost an average of 13.6 kg, about 30 lb. Of that, 5.3 kg, about 38%, was lean mass. In the SURMOUNT-1 body composition substudy, about a quarter of the weight lost was lean mass, in the tirzepatide and placebo groups alike.

Lean mass is not the same as muscle. On a DXA scan, lean mass also counts water, organs and other non-fat tissue. A 2025 joint advisory from four obesity and nutrition societies estimates that muscle is about half of lean mass, so roughly 20% of the total weight lost is muscle. The same advisory cites modeling that puts it at 10 to 15% of the weight lost in women and 20 to 25% in men when there is no structured strength training.

Do the arithmetic on a 50 lb loss. At 20%, about 10 lb of it would be muscle if you do nothing to protect it.

That is the case for starting on day one. Much of that 10 lb is preventable.

Muscle loss is not a direct effect of GLP-1 medications. It's a consequence of losing a lot of weight in a calorie deficit. GLP-1s suppress appetite and slow stomach emptying, so you eat much less, and your body covers part of the gap by breaking down muscle. The advisory notes that observed calorie intake drops by 16 to 39% on these drugs.

Three things make it worse:

• Too little protein. Protein is filling, so when appetite is already low, people drift toward easier foods like crackers, smoothies and soft carbs.
• No strength training. Without it, your body has little reason to keep muscle. Walking and cardio are good for your heart, but they don't send the same signal.
• Very fast weight loss. Eating very little makes it hard to get enough protein or train well, and the advisory links faster, deeper calorie restriction to more lean mass loss.

Fix those three and you've handled most of the problem. The steps below do it in order.

Here's what about 140g of protein looks like in small, GLP-1-friendly portions. Protein is estimated from USDA FoodData Central, so your brands will vary a little.

Total: 36 + 30 + 38 + 38 = 142g of protein and about 1,350 calories. With the snack, 156g and about 1,450 calories.

Your own calorie needs may be higher or lower. For many men, 1,450 calories is below the 1,800 the advisory flags for nutrient gaps, so ask your care team if you're unsure.

If mornings are hard, our High Protein Overnight Oats (20g protein, $3.49 a pouch) are ready when you wake up. For lunch and dinner, Build A Meal Plan lets you pick meals one by one and filter them by protein: 20 to 30g, 31 to 40g, or 41g and up. Every meal's calories and protein are on our Nutrition Info page.

For more days like this one, see our 7-day GLP-1 meal plan and our GLP-1 breakfast ideas.

Food comes first, but three supplements have reasonable evidence:

• Protein powder (whey or plant): the easiest way to close a protein gap when appetite is low. 20 to 30g per serving as needed. The advisory names shakes and fortified products as a way some people reach their target.
• Creatine monohydrate: supports strength and lean mass when combined with strength training, with a strong safety record in healthy adults, per the International Society of Sports Nutrition. Take 3 to 5g a day. Expect a small scale increase in the first weeks from water stored in muscle, about 0.5 to 1 liter in early studies, or roughly 1 to 2 lb. It isn't fat.
• Vitamin D: the advisory lists it among the nutrients to consider supplementing during GLP-1 treatment. Get your level checked and supplement if needed. Don't exceed 4,000 IU a day, the adult upper limit, unless your doctor tells you to.

Skip fat burners, heavy pre-workouts (they can worsen nausea) and "muscle preservation" blends. If you take other medications or have kidney disease, check with your doctor before adding supplements.

The scale alone can't tell you whether you're losing fat or muscle. Check monthly:

• Strength: you're lifting the same or more than last month.
• Waist: your waist measurement is shrinking faster than your shoulders and thighs.
• Body composition: a DEXA scan every 3 to 6 months is the most accurate option. Prices vary a lot by clinic, so ask before you book. A bioimpedance scale is less accurate but tracks trends.

The same three habits apply at any age, but they matter more after 50, and a few targets change:

• You start with less muscle. Muscle mass declines by roughly 3 to 8% per decade after age 30, and faster after 60, per a review in Current Opinion in Clinical Nutrition and Metabolic Care. Losing more during weight loss has a bigger effect on strength, balance and fall risk.
• Muscle responds less to small protein doses. The PROT-AGE study group recommends adults over 65 get at least 1.0 to 1.2 g/kg a day, more if they're active, and about 25 to 30g of protein per meal.
• Strength training matters even more. Menopause, and the gradual drop in testosterone in men, make muscle harder to keep. The advisory names both as risk factors. Aim for three sessions a week if you can.
• Calcium and vitamin D needs rise. Women need 1,200 mg of calcium a day from age 51. Men need 1,000 mg until 70 and 1,200 mg from 71. Vitamin D rises from 600 to 800 IU a day at 71. Weight loss can also reduce bone density, so ask whether your DEXA scan should include a bone density baseline.
• Fiber and fluids matter more. Constipation is more common with age and is one of the most common GLP-1 side effects. Aim for about 21g of fiber a day for women or 30g for men after 50, spread fluids through the day, and eat smaller meals if nausea or reflux are a problem.

Muscle loss on GLP-1 medications is real but largely preventable. Eat about 80 to 120g of protein a day spread across your meals, strength train at least 2 to 3 times a week, and lose weight at a pace your prescriber is comfortable with. Start on day one rather than waiting until you notice muscle loss.

The medication handles appetite. The protein and the lifting are your part. If the hard part is getting 30g onto the plate three times a day, our High Protein Meal Plan adds 2 extra ounces of meat to each meal, about 10g more protein and 50 more calories than our regular recipes, from $63.00 for 6 meals. For more on eating well on a GLP-1, see our complete GLP-1 diet guide.