10 Nutrient Deficiencies to Watch for If You’re Taking a GLP-1 Drug

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 may also mean consuming fewer essential nutrients, said Holly Wyatt, MD, assistant professor in the Division of Endocrinology, Metabolism and Diabetes at the University of Colorado Anschutz. Health.

Here are 10 nutritional deficiencies to watch out for when taking GLP-1.

Research suggests that people taking GLP-1 do not consume enough protein, a macronutrient necessary for building and repairing tissues. Protein becomes especially important during rapid weight loss, when fat and muscle may be lost. If you are perimenopausal or postmenopausal, have low testosterone levels, don’t do weight training, or sit most of the day, adequate protein intake is even more important.

Experts generally recommend adults consume 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 weigh 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 in the gaps.

Many adults in the United States don’t get enough vitamin D, but the problem may be even more pronounced for people taking GLP-1. According to a 2025 study, vitamin D deficiency among GLP-1 users increased from approximately 7.5% six months after starting treatment 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 food sources include salmon, trout, and certain mushrooms. If your doctor determines that you have a deficiency, he or she may recommend a supplement.

GLP-1 users may also have a calcium deficiency, which makes sense because calcium absorption requires vitamin D, another nutrient that people who take this drug are typically lacking.

One study found that on average, GLP-1 users have a calcium deficiency of 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 food sources include leafy greens, milk, yogurt and cheese.

Another nutrient that GLP-1 users might be deficient in is iron. The same study found that people taking GLP-1 have an iron deficiency of 12.1 mg per day on average (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 can cause shortness of breath, hair loss, dizziness and other symptoms.

Foods rich in iron include lentils, meats and seafood.

Magnesium is another nutrient that GLP-1 users may be lacking. Research suggests they are missing an average of 266 mg per day (the RDA is 420 mg).

The mineral plays an important role in maintaining healthy muscles, nerves, bones and blood sugar levels. Foods like avocados, spinach, nuts and whole grains can help increase magnesium intake.

A common deficiency among GLP-1 users is potassium, an essential mineral that acts as an electrolyte and is essential for healthy muscles, nerves and fluid balance. While the RDA for potassium is 4,700 mg per day, researchers found that people taking GLP-1 were deficient by an average of 2,186 mg per day.

Fruits, vegetables, and soy products are solid sources of potassium.

Taking a GLP-1 can make it harder to get certain key vitamins. Research shows that people taking GLP-1 medications have, on average, deficiencies 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 are better absorbed when consumed with dietary fat. Low-fat meals can therefore reduce absorption.

Good sources of vitamin A include sweet potatoes and carrots, foods rich in vitamin C include peppers and broccoli, and nuts and spinach are good sources of vitamin E.

Most people in the United States do not consume enough fiber, and the use of GLP-1 may 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 28g of fiber per day from foods such as nuts, vegetables and fruit.

Staying hydrated is equally important, as dehydration can worsen constipation, a common problem among GLP-1 users. Research suggests that 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 per day and include water-rich foods like cucumbers and watermelon in your diet.

Common signs of a nutritional deficiency include:

• Fatigue
• Excessive hair loss
• Itchy or flaking skin
• Poor wound healing
• Unusual bruising
• Numbness
• Hair and nail changes
• Increased hunger
• Food Cravings
• Muscle discoordination
• Difficulty concentrating
• Mood changes

If you have symptoms, talk to your doctor about checking your blood levels, Wyatt said. She also recommends seeing a dietitian if possible, who may suggest taking a daily multivitamin, especially if you eat fewer than 1,200 calories per day, avoid major food groups, or are losing weight quickly.