GLP-1 medications like Ozempic and Wegovy, popular for weight loss and diabetes treatment, slow the rate at which food moves through your digestive tract and help suppress appetite. But eating less can also mean taking in fewer essential nutrients, Holly Wyatt, MD, an adjoint associate professor in the Division of Endocrinology, Metabolism, and Diabetes at the University of Colorado Anschutz, told Health.
Here are 10 nutrient deficiencies to look out for while taking a GLP-1.
Research suggests that people taking GLP-1s don’t consume enough protein, a macronutrient needed to build and repair tissues. Protein becomes especially important during rapid weight loss, when both fat and muscle can be lost. If you’re perimenopausal or have gone through menopause, have low testosterone, don’t strength train, or sit for most of the day, getting adequate protein matters even more.
Experts generally recommend that adults aim for about 1.2 grams of protein per kilogram of body weight per day—and up to 1.6 g/kg during weight loss. If you’re 200 pounds, that’s about 109 grams per day.
Good sources of protein include beans, lentils, and lean meats like grilled chicken. Protein powders and supplements can also help fill any gaps.
Many adults in the U.S. don’t get enough vitamin D, but the issue can be even more pronounced for people taking GLP-1s. According to a 2025 study, vitamin D deficiency among GLP-1 users increased from about 7.5% at six months after starting the drug to 13.6% after 12 months. Vitamin D is necessary for strong bones and healthy muscles, so it’s especially important to get enough if you’re losing bone and muscle during weight loss.
Your body produces vitamin D when exposed to sunlight, and good dietary sources include salmon, trout, and certain mushrooms. If your doctor determines you’re deficient, they may recommend a supplement.
GLP-1 users may also be deficient in calcium, which makes sense because calcium absorption requires vitamin D—another nutrient people taking the medication commonly lack.
One study found that, on average, GLP-1 users are deficient in calcium by about 863 mg per day (for reference, the recommended daily allowance—or RDA—is 1,300 mg).
Calcium is essential for strong bones, muscle function, blood clotting, and other vital processes. Good dietary sources include leafy greens, milk, yogurt, and cheese.
Another nutrient GLP-1 users may miss out on is iron. The same study found that people taking GLP-1s are deficient in iron by an average of 12.1 mg per day (the RDA is 18 mg).
Iron is an essential mineral and a key component of hemoglobin, the protein in red blood cells that carries oxygen from the lungs to the rest of your body. Low iron levels can lead to anemia, which may cause shortness of breath, hair loss, dizziness, and other symptoms.
Iron-rich foods include lentils, meats, and seafood.
Magnesium is another nutrient GLP-1 users may lack. Research suggests they are missing an average of 266 mg per day (the RDA is 420 mg).
The mineral plays a big role in maintaining healthy muscles, nerves, bones, and blood sugar levels. Foods like avocados, spinach, nuts, and whole grains can help boost magnesium intake.
A common deficiency among GLP-1 users is potassium, an essential mineral that acts as an electrolyte and is critical for healthy muscles, nerves, and fluid balance. While the RDA of potassium is 4,700 mg per day, researchers found that people taking GLP-1s were missing out on an average of 2,186 mg daily.
Fruits, vegetables, and soy products are solid sources of potassium.
Taking a GLP-1 may make it harder to get certain key vitamins. Research shows that people on GLP-1 medications are, on average, deficient in:
- Vitamin A: 560 mcg (RDA: 900 mcg)
- Vitamin C: 51 mg (RDA: 90 mg)
- Vitamin E: 9.6 mg (RDA: 15 mg).
Vitamins A and E are fat soluble, meaning they’re best absorbed when eaten with some dietary fat—so low-fat meals may reduce absorption.
Good sources of vitamin A include sweet potatoes and carrots, vitamin C-rich foods include bell peppers and broccoli, and nuts and spinach are good sources of vitamin E.
Most people in the U.S. don’t get enough fiber, and GLP-1 use can make deficiencies even more likely. Adequate fiber intake is especially important while taking the medication because constipation is a common side effect, and fiber supports healthy digestion.
Aim for at least 28 g of fiber daily from foods such as nuts, veggies, and fruit.
Staying hydrated is equally important, as dehydration can worsen constipation—a frequent issue for GLP-1 users. Research suggests many GLP-1 users are dehydrated, likely due to a lack of water and low electrolytes, Wyatt said.
If you’re on a GLP-1, aim for 2 to 3 liters of fluid daily and incorporate water-rich foods like cucumbers and watermelon into your diet.
Common signs of a nutritional deficiency include:
- Fatigue
- Excessive hair loss
- Itchy or flaky skin
- Poor wound healing
- Unusual bruising
- Numbness
- Hair and nail changes
- Increased hunger
- Food cravings
- Muscle discoordination
- Trouble concentrating
- Mood changes
If you have symptoms, talk with your doctor about getting your blood levels checked, Wyatt said. She also recommends seeing a dietitian if possible, who may suggest taking a multivitamin daily—especially if you’re eating less than 1,200 calories a day, are avoiding major food groups, or losing weight quickly.
