GLP-1 Nutrient Deficiency Risk Checker
Answer 10 quick questions about your diet on GLP-1 medication to check your risk for vitamin B12, iron, calcium, vitamin D, and protein deficiencies
Your Nutrient Deficiency Risk Profile
Recommended Food Sources for Your At-Risk Nutrients
Understanding Nutrient Deficiencies on GLP-1 Medications
GLP-1 receptor agonists such as semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound) work by slowing gastric emptying, reducing appetite, and decreasing overall food intake. While these mechanisms are effective for weight loss, they also create a significant risk for nutrient deficiencies. When you eat substantially less food, your intake of essential vitamins and minerals drops proportionally. Research from 2025-2026 estimates that the average GLP-1 user reduces caloric intake by 30-40%, which can lead to sub-optimal levels of multiple critical nutrients within just a few months of treatment. Vitamin B12 is particularly vulnerable because GLP-1 medications reduce stomach acid production, which is required for B12 absorption from food.
Iron deficiency is one of the most common nutritional gaps among GLP-1 users, especially women of reproductive age. The reduced appetite caused by these medications often leads to decreased consumption of iron-rich foods like red meat, which is the most bioavailable source of heme iron. Plant-based iron (non-heme iron) from spinach, lentils, and beans is less efficiently absorbed, and its absorption is further compromised when overall food volume drops. A 2025 GNC study found that 86% of GLP-1 users fail to meet their daily protein needs, and since many protein-rich foods are also primary iron sources, the two deficiencies often occur together. Symptoms of iron deficiency include persistent fatigue, pale skin, shortness of breath, and difficulty concentrating.
Calcium and vitamin D deficiencies present a particular concern for bone health during rapid weight loss on GLP-1 therapy. Many patients report nausea triggered by dairy products, leading to dramatically reduced calcium intake. Since vitamin D is a fat-soluble vitamin, its absorption depends on adequate dietary fat intake, which is often significantly reduced on GLP-1 medications as fatty foods are among the most common nausea triggers. Additionally, rapid weight loss itself has been associated with decreased bone mineral density. The combination of lower calcium intake, reduced vitamin D absorption, and accelerated bone turnover from weight loss creates a perfect storm for bone health deterioration, making supplementation and dietary monitoring essential during treatment.
The good news is that nutrient deficiencies on GLP-1 medications are largely preventable with awareness and proactive planning. Strategic food choices that maximize nutrient density in smaller portions, consistent supplementation with a high-quality multivitamin, and regular blood work monitoring can effectively mitigate these risks. Prioritize nutrient-dense foods at every meal: eggs and fortified cereals for B12, lean meats and leafy greens for iron, fortified plant milks and cheese for calcium, and fatty fish plus moderate sun exposure for vitamin D. Work with your healthcare provider to establish a blood work monitoring schedule, typically every 3-6 months, to catch any developing deficiencies early and adjust your nutrition and supplementation plan accordingly.
How to Use This GLP-1 Nutrient Deficiency Checker
- Answer each of the 10 multiple-choice questions honestly, focusing on your current diet and lifestyle since starting GLP-1 medication.
- Use the Next and Previous buttons to navigate through questions. Each question must be answered before proceeding.
- After completing all 10 questions, click the "Check My Risk" button to generate your personalized nutrient deficiency risk profile.
- Review your individual risk gauges for Vitamin B12, Iron, Calcium, Vitamin D, and Protein to see which nutrients need the most attention.
- Explore the recommended food source cards and supplementation guidance for each at-risk nutrient, and share your results with your healthcare provider.
Frequently Asked Questions
Why do GLP-1 medications increase the risk of nutrient deficiencies?
GLP-1 medications like Ozempic, Wegovy, and Mounjaro significantly reduce appetite and slow gastric emptying, leading to a 30-40% decrease in food intake for most users. This means substantially lower consumption of vitamins and minerals. Additionally, GLP-1 drugs may reduce stomach acid production, which impairs absorption of nutrients like vitamin B12 that require an acidic environment. The combination of eating less food and absorbing less from what you do eat creates a dual risk for deficiency.
What are the most common nutrient deficiencies on Ozempic?
The most commonly reported nutrient deficiencies among GLP-1 users include vitamin B12 (due to reduced stomach acid and lower intake of meat and dairy), iron (from decreased consumption of red meat and overall reduced food volume), calcium (from lower dairy intake often caused by nausea), vitamin D (from reduced fat intake impairing absorption of this fat-soluble vitamin), and protein (with 86% of GLP-1 users not meeting daily protein needs according to recent studies). All five nutrients require proactive monitoring and dietary planning during treatment.
Should I take supplements while on GLP-1 medication?
Most healthcare providers recommend at minimum a daily high-quality multivitamin for GLP-1 users. Depending on your diet and blood work results, additional individual supplements may be warranted, such as sublingual B12 (1000mcg), iron bisglycinate (18-27mg for women), calcium citrate (500-600mg split into two doses), and vitamin D3 (1000-2000 IU daily). Always consult your prescribing physician before starting supplements, as some can interact with medications or need to be taken at specific times relative to your GLP-1 injection.
How do I know if I have a vitamin B12 deficiency on GLP-1?
Common symptoms of B12 deficiency include persistent fatigue and weakness, tingling or numbness in hands and feet, difficulty concentrating or brain fog, mood changes or depression, pale or jaundiced skin, and a swollen or inflamed tongue. These symptoms can develop gradually over months. Since GLP-1 medications slow gastric emptying and may reduce intrinsic factor production, B12 from food sources becomes harder to absorb. A simple blood test measuring serum B12 and methylmalonic acid levels can confirm deficiency. If you experience neurological symptoms like tingling, seek medical attention promptly.
Can GLP-1 medications cause bone loss from calcium and vitamin D deficiency?
Rapid weight loss on GLP-1 medications has been associated with decreased bone mineral density in clinical studies. When combined with reduced calcium intake (due to dairy aversion from nausea) and impaired vitamin D absorption (from lower fat consumption), the risk to bone health increases significantly. This is especially concerning for postmenopausal women and older adults who are already at elevated risk for osteoporosis. Weight-bearing exercise, adequate calcium and vitamin D supplementation, and regular bone density screening are recommended for long-term GLP-1 users.
How often should I get blood work done on GLP-1 medication?
Most obesity medicine specialists recommend comprehensive blood work every 3-6 months while on GLP-1 medication, especially during the first year. Key tests include a complete blood count (CBC) for iron status, serum vitamin B12, 25-hydroxyvitamin D, serum calcium, and a comprehensive metabolic panel. If you have risk factors such as vegetarian/vegan diet, history of gastric issues, or are losing weight rapidly, more frequent monitoring may be warranted. Establishing baseline levels before starting medication is ideal so changes can be tracked accurately.
What foods should I prioritize to prevent deficiencies on GLP-1 drugs?
When appetite is reduced, every bite counts. Prioritize nutrient-dense foods: eggs (B12, iron, protein, vitamin D), fatty fish like salmon (B12, vitamin D, protein, omega-3s), fortified cereals and plant milks (B12, calcium, vitamin D, iron), dark leafy greens (iron, calcium), lean meats and poultry (B12, iron, protein), Greek yogurt (B12, calcium, protein), lentils and beans (iron, protein), and nuts and seeds (iron, calcium, healthy fats). Focus on getting protein at every meal to meet the higher demands during rapid weight loss, and consider nutrient-dense smoothies if solid food triggers nausea.
