Table of Contents

GLP-1 receptor agonists like semaglutide (Ozempic, Wegovy), liraglutide (Victoza, Saxenda), dulaglutide (Trulicity), and the dual agonist tirzepatide (Mounjaro, Zepbound) are highly effective medications for type 2 diabetes and obesity. These drugs work by mimicking hormones that reduce appetite, slow stomach emptying, and help regulate blood sugar.

However, reduced hunger may also lead to lower intake of essential nutrients. A large study of more than 460,000 adults starting GLP-1 therapy found that 12.7% had a nutritional deficiency diagnosis within six months, and 22.4% did within one year. In addition to micronutrient gaps, muscle loss is a concern. Studies of people on semaglutide report that roughly 40% of the weight lost comes from lean tissue.

Marie Spreckley from the University of Cambridge explained that without proper nutrition support during treatment, one health problem could end up being replaced by another.

The sections below outline ten nutrients that often fall short among GLP-1 users, along with symptoms of deficiency, simple food sources, and tips to help you stay nourished.

Key Takeaways

  • Most nutrient gaps are linked to reduced intake and unmanaged gastrointestinal side effects rather than a direct effect of GLP-1 medications, and can often be prevented with targeted nutrition planning.
  • Reported nutrient gaps in GLP-1 users include low vitamin D, protein, iron, calcium, magnesium, potassium, vitamin B12, thiamine (rare cases), vitamin C, and choline.
  • Vitamin D is the most commonly reported deficiency.
  • About 40% of weight lost on semaglutide may come from lean mass, increasing the need for 1.2-2.0 g/kg of daily protein during weight loss.

1. Vitamin D

Vitamin D is essential for calcium absorption, immune function, and muscle health. Reduced food intake and low-fat diets may contribute to low vitamin D, since dietary fat helps absorb this fat-soluble vitamin.

In the large study mentioned earlier, the most common deficiency identified was vitamin D. A more recent review reported similar findings, reported in 7.5% of participants at six months and 13.6% at 12 months.

In a separate study, nearly all participants (98.6%) failed to meet the recommended 15 mcg (600 IU) of vitamin D per day.

Symptoms of low vitamin D may include:

    • bone pain
    • muscle weakness
    • frequent infections
    • fatigue

Vitamin D also supports mood and cognitive function.

How to get more vitamin D

Sunlight triggers vitamin D synthesis in the skin, but people living in northern latitudes or avoiding sun exposure may need to rely on food and supplements. Good food sources include:

    • fatty fish (salmon, mackerel, sardines)
    • egg yolks
    • fortified dairy or plant milks

If a daily supplement is needed, talk with your doctor before starting one because too much vitamin D can cause toxicity.

2. Protein

Muscle is a metabolically active tissue that helps regulate blood sugar, supports movement, and burns calories. Reduced appetite makes it harder to eat enough protein.

In one study, people on GLP-1 were getting about 18.5% of their calories from protein, which is acceptable for an average adult. But for someone taking a GLP-1 medication and actively losing weight, that likely isn’t enough.

When you lose weight, you don’t just lose fat. You can also lose muscle. To help protect muscle, experts recommend eating more protein than the general minimum guideline. Instead of 0.8 grams per kilogram of body weight per day, people trying to preserve muscle during weight loss may need about 1.2 to 2.0 grams per kilogram per day.

In the study:

    • Only 43% were eating at least 1.2 g/kg
    • Only 10% reached 1.6 g/kg
    • Only 5% reached 2.0 g/kg

The usual protein recommendations are based on minimum needs for the average adult, but this may not fully apply to GLP-1 users. A press release from the Endocrine Society noted that about 40% of weight lost from semaglutide was lean mass, with women and older adults at higher risk.

Signs of inadequate protein include:

    • muscle wasting
    • fatigue
    • hair thinning
    • slow wound healing

People may also experience cravings and reduced exercise capacity.

How to get more protein

Aim for lean protein at each meal. Good options include:

    • fish
    • poultry
    • lean beef
    • eggs
    • tofu
    • beans
    • lentils
    • greek yogurt
  • cottage cheese

Spread protein intake evenly through the day and consider a protein smoothie with fruits and spinach if your appetite is low. Combine protein with resistance exercises to maintain muscle.

Always speak with your prescriber before using protein supplements, as some shakes can cause bloating or nausea when stomach capacity is reduced.

3. Iron

Iron carries oxygen in red blood cells and supports energy metabolism. However, recent research suggests GLP-1 medications may reduce iron absorption. In a 10-week clinical study involving semaglutide users, iron absorption dropped by about 13% on average. About 18% of participants had a 30% or greater drop.

To add, the average iron intake of GLP-1 users was 12.1 mg per day, which is well below the 18 mg Dietary Reference Intake (DRI) for adults.

A small observational review also observed iron depletion. Ferritin levels, which show how much iron is stored in the body, were 26-30% lower among GLP-1 users compared to patients taking SGLT2 inhibitors.

These could all increase the risk of iron deficiency or anemia. Symptoms include:

    • fatigue
    • pale skin
    • shortness of breath
    • brittle nails
    • restless legs

How to get more iron

Iron is abundant in:

    • beef
    • liver
    • dark poultry meat
    • clams
    • oysters

Plant sources include:

    • lentils
    • chickpeas
    • black beans
    • spinach
    • pumpkin seeds

But note that plant-based iron is less absorbable. Eating vitamin C-rich foods (like citrus or bell peppers) with plant iron improves absorption.

Avoid taking iron supplements unless your doctor confirms a deficiency. Excess iron can be harmful and can be fatal, leading to severe organ damage, particularly in the liver, heart, and pancreas.

4. Calcium

Calcium is vital for bones, nerve transmission, and muscle contraction. Average calcium intake among GLP-1 users was 862 mg per day, far below the 1,300 mg DRI for adults.

Inadequate calcium combined with low vitamin D may increase the risk of osteoporosis or fractures. Symptoms of low calcium may include:

    • muscle cramps
    • numbness or tingling
    • brittle nails

Long-term deficiency can lead to bone loss.

How to get more calcium

Dairy foods such as milk, yogurt, and cheese are rich sources. Non-dairy options include:

    • calcium-fortified plant milks
    • tofu set with calcium sulfate
    • canned sardines
    • salmon with bones
    • dark leafy greens like kale and bok choy

Spread calcium intake throughout the day to improve absorption and pair with vitamin D-rich foods for better uptake.

Avoid taking calcium supplements without medical guidance. A large cohort study found that GLP-1 users had higher rates of hypercalcemia, or elevated blood calcium levels, compared to non-users. Tirzepatide showed the strongest association, increasing hypercalcemia risk by 85%. Semaglutide showed similar effects, while dulaglutide and liraglutide had smaller increases.

Supplementation should be individualized and monitored by a clinician.

5. Magnesium

Magnesium assists in muscle and nerve function, blood sugar control, blood pressure regulation, and bone health. The average magnesium intake of GLP-1 users was 266 mg per day against a 420 mg DRI, and 89.9% of participants were below the recommended intake. Older adults with type 2 diabetes already have a higher risk of low magnesium.

One case report described a 73-year-old woman with type 2 diabetes who developed severe hypomagnesemia after using semaglutide along with multiple other medications known to lower magnesium, including metformin and esomeprazole. She collapsed at home and was found to have extremely low magnesium levels, along with low calcium.

This is possibly due to side effects like vomiting and diarrhea or concurrent use of proton pump inhibitors.

Symptoms of magnesium deficiency can include:

    • muscle spasms
    • tremors
    • fatigue
    • irregular heartbeat
    • anxiety
    • headaches

How to get more magnesium

Choose nuts (almonds, cashews), seeds (pumpkin, chia), whole grains, legumes, and leafy greens. Avocado and dark chocolate also supply magnesium. Consider including a magnesium-rich snack like a handful of almonds or a spinach salad.

Avoid self-medicating with magnesium supplements because excess magnesium can cause diarrhea or heart complications.

6. Potassium

Potassium helps maintain fluid balance, blood pressure, and normal muscle and nerve function. Some GLP-1 users experience nausea, vomiting, or diarrhea, especially during dose escalation. These side effects can lead to fluid loss and reduced potassium levels or hypokalemia.

Reports show that the average potassium intake of GLP-1 users was about 2,185 mg daily, which is less than half the 4,700 mg DRI, and 98.6% of participants consumed below the recommended amount.

Two case reports describe women who developed severe low potassium levels while taking semaglutide. A 48-year-old woman with type 2 diabetes was hospitalized twice with potassium levels as low as 2.6-2.7 mmol/L after months of nausea and vomiting on semaglutide.

A second 45-year-old woman taking semaglutide for weight loss experienced potassium drops to 2.5 mmol/L and required hospitalization, particularly while also using a diuretic.

For comparison, the normal range in adults is generally 3.5-5.5 mmol/L.

Mild to moderate hypokalemia may not cause noticeable symptoms and is usually managed with oral potassium supplements and increased dietary intake. However, severe hypokalemia can become dangerous and may trigger serious complications, such as:

    • abnormal heart rhythms
    • breathing difficulty
    • kidney dysfunction

Low potassium levels can also cause muscle weakness that often begins in the legs and gradually spreads to the torso and arms.

How to get more potassium

Foods rich in potassium include:

    • avocados
    • bananas
    • raisins
    • oranges
    • melons
    • beans
    • lentils
    • potatoes
    • winter squash

Avoid taking potassium supplements without a doctor’s supervision because too much can lead to dangerous heart arrhythmias. If GLP-1 side effects like vomiting and diarrhea persist, call your prescriber so that they can adjust your dose or check your electrolyte levels.

7. Vitamin A and vitamin E

Vitamins A and E are fat-soluble antioxidants. Vitamin A supports vision, immune function, and skin health, while vitamin E protects cells from oxidative damage. People with obesity or type 2 diabetes often have lower levels of these vitamins.

GLP-1 users are usually advised to follow a lower-fat diet to minimize gastrointestinal side effects, but fat is needed to absorb vitamins A and E. The average vitamin A intake of GLP-1 users was 559 mcg (DRI is 900 mcg), and vitamin E intake was 9.6 mg (DRI is 15 mg).

Symptoms of vitamin A deficiency may include dry skin, night blindness, and frequent infections. While vitamin E deficiency can cause nerve problems, muscle weakness, and immune impairment.

How to get more vitamin A and E

Vitamin A is abundant in orange and dark-green vegetables such as sweet potatoes, carrots, pumpkin, spinach, and kale. Vitamin E is found in nuts, seeds (sunflower, almonds), wheat germ, and vegetable oils.

Include a little healthy fat like olive oil or avocado when eating plant foods to aid absorption. Talk with your doctor before taking high-dose vitamin A or E supplements because excessive amounts can be toxic.

8. Cobalamin (Vitamin B12)

Vitamin B12 (cobalamin) is needed for red blood cell formation, energy metabolism, and nervous system health.

Many people with type 2 diabetes already have low B12 levels due to metformin therapy, which is often used alongside GLP-1 drugs. In a study of adults with type 2 diabetes, 28.3% of patients taking metformin had vitamin B12 deficiency. The risk was about twice as high in those who had used metformin for more than five years.

So, if you are taking metformin and a GLP-1 medication at the same time, regular vitamin B12 monitoring may be important, especially with long-term use. Symptoms of low vitamin B12 include:

    • fatigue
    • weakness
    • numbness or tingling in hands and feet
    • memory problems
    • mood changes

Severe deficiency can cause nerve damage and anemia.

How to get more vitamin B12

B12 is found in animal foods, such as meat, poultry, fish, eggs, and dairy. If you’re following a vegetarian or plant-based diet, you may need fortified foods like nutritional yeast and fortified plant milks, or supplements.

9. Thiamine (Vitamin B1)

Thiamine helps convert food into energy and supports nervous system function. Although deficiencies are uncommon in the general population, severe calorie restriction, vomiting, or malabsorption can cause thiamine depletion. In rare cases, it may progress to Wernicke encephalopathy (WE), which is a serious brain condition.

A pharmacovigilance study using FDA adverse event data identified 15 reported cases of WE linked to semaglutide and tirzepatide.

The majority of patients experienced severe gastrointestinal symptoms such as vomiting, appetite loss, significant weight loss, or malnutrition before developing neurological complications.

In one case report, a 37-year-old woman developed severe progressive weakness and nerve damage after rapid weight loss on semaglutide, losing 45 kg (100 lbs) in about 10 weeks. She experienced persistent nausea and vomiting, followed by multiple vitamin deficiencies, including low vitamin B1, vitamin D, and folate.

Semaglutide was not directly proven to be the cause, but the rapid weight loss, poor intake, and micronutrient deficiencies during treatment likely contributed.

Although rare, these findings suggest that thiamine deficiency may occur in vulnerable patients, particularly those with prolonged nausea and poor nutritional intake. Symptoms of thiamine deficiency include:

    • fatigue
    • irritability
    • peripheral neuropathy
    • muscle weakness

In severe cases, confusion, vision changes, and heart problems may occur.

How to get more vitamin B1

Whole grains, enriched breads and cereals, pork, fish, legumes, and seeds are good sources of thiamine. Thiamine is water-soluble and not stored in large quantities, so regular intake is important.

If you experience persistent vomiting or rapid weight loss, speak with your doctor. They may recommend thiamine supplementation.

10. Vitamin C and choline

Vitamin C is a water-soluble nutrient important for collagen synthesis, immune defense, and antioxidant protection. The study on GLP-1 users reported average vitamin C intake of 51 mg per day (DRI 90 mg).

Because vitamin C is not stored long-term in large amounts, low intake for 4 to 12 weeks can lead to deficiency, and could progress to scurvy.  There has been growing discussion about scurvy in some GLP-1 users. Signs of vitamin C deficiency include easy bruising, bleeding gums, slow wound healing, and fatigue.

Choline, an essential nutrient involved in neurotransmitter synthesis and liver function, averaged 304 mg per day versus the 550 mg DRI, and 94.2% of participants consumed less than the recommended amount.

Choline deficiency can cause fat accumulation in the liver, muscle damage, and cognitive issues.

How to get more vitamin C and choline

Boost vitamin C by eating citrus fruits, kiwi, strawberries, peppers, broccoli, and tomatoes. On the other hand, choline is found in eggs, liver, chicken, fish, shiitake mushrooms, soybeans, and quinoa. Including a variety of fruits, vegetables, and protein sources will help cover these nutrients.

Tips for staying nourished while using GLP-1 medications

Here’s how to stay properly nourished while using GLP-1 medications:

    • Plan balanced meals: Even with less appetite, aim to include a source of protein, complex carbohydrates, healthy fats, and colorful fruits or vegetables at each meal. Smaller, nutrient-dense meals can meet nutrient needs without overwhelming your stomach.
    • Track your intake: Use a food diary or app to monitor calories, protein, and micronutrients. This can highlight gaps that you can discuss with your healthcare provider.
    • Hydrate and manage side effects: Sip water throughout the day and separate fluids from meals if you experience nausea or fullness. If vomiting or diarrhea persists, seek medical advice.
    • Consider professional guidance: Consult a registered dietitian experienced in obesity or diabetes medicine. They can tailor recommendations to your health status, preferences, and treatment plan, and they may order labs to check nutrient levels.
    • Exercise for muscle maintenance: Incorporate strength training and regular movement. Resistance exercises paired with adequate protein help preserve lean mass.
    • Avoid unverified supplements: Do not add weight-loss supplements or high-dose nutrients without your doctor’s approval. Excessive vitamins or minerals can be harmful, and some supplements may interact with your medication.

Bottom line

GLP-1 medications are highly effective for weight loss and blood sugar control, but reduced appetite can increase the risk of nutrient gaps. Studies show deficiencies in vitamin D, protein, iron, B12, magnesium, potassium, vitamin C, and others may occur, especially with rapid weight loss or persistent gastrointestinal side effects.

Most risks are linked to lower intake rather than a direct drug effect. Staying nourished through balanced meals, adequate protein, routine lab monitoring, and medical guidance helps protect muscle, prevent deficiencies, and support long-term health.

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Frequently Asked Questions

Avoid “blood sugar” or “weight-loss” supplements because they can stack with GLP-1 effects and raise the risk of low glucose, especially if you also use insulin or a sulfonylurea or you are skipping meals.

The best supplements to take with GLP-1 medications like Ozempic, Wegovy, or Mounjaro include protein and creatine for muscle preservation, fiber to ease constipation, and a multivitamin to prevent deficiencies if you’re eating very little. Be cautious with fat burners, high doses of green tea, and “metabolism boosters,” as they don’t enhance results and may worsen side effects. Focus on adequate protein, resistance exercise, sleep, and hydration for better long-term progress. Consult your doctor before starting any supplement to ensure it’s safe for you.

Ozempic does not “deplete” nutrients directly in the way malabsorption disorders do, but it can reduce appetite and slow gastric emptying, which can lower overall intake and diet variety. Reported micronutrient deficiencies after Ozempic commonly include vitamin D and sometimes B vitamins and minerals, often linked to reduced food intake.

It can contribute indirectly if you eat less of the main B12 sources (animal foods) or if nausea leads to a narrower diet. In one study after gastric surgery, semaglutide treatment was associated with decreases in serum vitamin B12 alongside reduced protein intake patterns, suggesting intake changes as a contributor.

GLP-1 drugs generally do not cause true nutrient malabsorption, but lower calorie intake can increase the chance of not meeting needs for protein and several micronutrients. Expert and studies commonly flags vitamin D, protein, iron, calcium, magnesium, potassium, B vitamins, vitamin C, and choline as nutrients to watch in some patients on GLP-1 therapy.

The idea that low vitamin B12 directly causes specific cravings for red meat, fish, eggs, or dairy is not well supported by clinical evidence. Some people may experience fatigue-related sugar cravings due to low energy levels, but this is nonspecific and not considered a diagnostic sign of B12 deficiency.

Most adults need about 2.4 mcg/day of vitamin B12.

Severe deficiency can cause fatigue and weakness from anemia and neurologic symptoms such as numbness or tingling, balance problems, and cognitive or mood changes.

There is no meaningful interaction expected between vitamin D and GLP-1 medications.

Prioritize resistance training and physical activity. Regular strength training using weights, bands, or body-weight exercises signals your body to maintain and build muscle even as you lose weight. Eat enough protein, ideally ~1.2 g/kg/day or higher, and spread it across meals to support muscle protein synthesis during weight loss.

The best-tolerated choice often depends on your symptoms, since some forms are more likely to cause diarrhea at higher supplemental doses. Magnesium glycinate is often preferred for sleep and anxiety because it is well absorbed and less likely to cause diarrhea. Magnesium citrate is commonly used for constipation, magnesium L-threonate is studied for brain health, and magnesium malate is often chosen for energy support and muscle discomfort.

Aim for small, nutrient-dense portions with protein first (for example, yogurt, eggs, cottage cheese, tofu, protein smoothies) and add fruits or vegetables in forms that feel easier to tolerate (soups, cooked vegetables, blended options).

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