5 Nutrient Deficiencies Caused By Ozempic (Semaglutide)

The Hidden Nutritional Cost of GLP-1 Medications

Weight loss gets all the headlines when people talk about Ozempic and other GLP-1 medications. What does not get nearly enough attention is the nutritional fallout that can happen when you dramatically reduce your food intake. This video from Kait Malthaner, who has a background in nutrition and exercise science, covers five specific nutrient deficiencies that are common among semaglutide users, and it is a topic that deserves way more airtime than it gets.

The math is simple but important. If you were eating 2,500 calories a day and your GLP-1 medication brings that down to 1,400, you have just cut your food intake by 44%. That means your vitamin and mineral intake from food also dropped by roughly that amount, assuming you are eating the same types of food in smaller quantities. And since most Americans were already falling short on several key nutrients even before reducing their intake, the deficit can become clinically significant faster than people realize.

This is not a reason to avoid GLP-1 medications. The health benefits of weight loss typically outweigh the risks of temporary nutrient shortfalls, especially when those shortfalls are identified and addressed. But ignoring this issue entirely, which is what a lot of the popular GLP-1 content does, sets people up for problems that are entirely preventable.

The Big Five Deficiencies to Watch For

The video identifies five nutrients that GLP-1 users are most likely to fall short on. Protein is the most frequently discussed and arguably the most consequential. When you eat less food overall and do not specifically prioritize protein, your intake can easily drop below the level needed to maintain muscle mass. The recommended range for GLP-1 users is 1.2-1.6 grams of protein per kilogram of body weight daily, and many people on these medications are consuming half that amount without realizing it.

Iron deficiency is another concern, especially for premenopausal women who already have higher iron needs due to menstruation. Red meat is one of the primary dietary sources of heme iron (the form your body absorbs most efficiently), and many GLP-1 users develop meat aversions. If you find yourself unable to stomach red meat, you need alternative iron sources like lentils, spinach, fortified cereals, or potentially a supplement. But do not supplement iron without getting your levels tested first, because too much iron is harmful.

Vitamin D is already the most common nutrient deficiency in the general population, and reduced food intake makes it worse. Very few foods contain meaningful amounts of vitamin D (fatty fish, fortified milk, egg yolks), so even people eating a full diet often fall short. On a reduced-calorie diet, supplementation is almost certainly necessary. Most experts recommend 1,000-2,000 IU daily, though your doctor may suggest more based on your blood levels.

B Vitamins and Calcium

B12 and folate round out the list, and both are worth monitoring. B12 deficiency is particularly concerning because the symptoms (fatigue, weakness, numbness, cognitive fog) overlap with common complaints among GLP-1 users, making it easy to dismiss them as medication side effects when they are actually a nutritional problem. B12 is found primarily in animal products, so if your reduced appetite leads you to eat less meat, eggs, and dairy, your B12 status may decline.

Calcium deserves attention because rapid weight loss itself can affect bone density, and inadequate calcium intake makes this worse. GLP-1 users who are losing weight rapidly should aim for at least 1,000mg of calcium daily through food and supplementation. Dairy products are the most efficient source, but if dairy causes GI issues (which it can in some GLP-1 users), calcium-fortified non-dairy milks, canned sardines with bones, and leafy greens like kale can help fill the gap.

The video recommends getting bloodwork done before starting GLP-1 medication to establish baseline levels, and then rechecking at regular intervals. This is excellent advice that too few prescribers follow. A simple panel covering iron, vitamin D, B12, folate, and calcium can identify deficiencies before they become symptomatic, which is always preferable to treating them after the fact.

What the Video Gets Right

The focus on prevention rather than treatment is the strongest aspect. By identifying the most likely deficiencies and recommending proactive monitoring, the video gives viewers a framework for protecting their health while they pursue weight loss. The emphasis on food-first solutions (prioritizing nutrient-dense foods within your reduced calorie budget) before jumping to supplements is also well-reasoned.

The hair loss connection is mentioned and worth emphasizing. Iron, biotin, zinc, and protein deficiencies can all contribute to hair thinning and loss, which is one of the most distressing side effects reported by GLP-1 users. Much of this hair loss is driven by the rapid weight loss itself (telogen effluvium), but nutrient deficiencies can make it worse and delay recovery. Addressing the deficiencies does not always stop the hair loss, but it gives your body the best chance of recovering.

What It Misses

Magnesium is not on the list but probably should be. Magnesium deficiency is common in the general population and plays a role in muscle function, sleep quality, and glucose metabolism. Many GLP-1 users report muscle cramps, poor sleep, and increased anxiety, all of which can be related to low magnesium. Foods like nuts, seeds, dark chocolate, and leafy greens are good sources, and a magnesium glycinate supplement is well-tolerated and widely recommended.

Zinc is another oversight. Zinc supports immune function, wound healing, and taste perception. Some GLP-1 users report changes in taste, and while this is likely a direct medication effect, low zinc can contribute. Oysters are the single best food source of zinc, but for people who are not regular oyster eaters, pumpkin seeds, beef, and chickpeas are practical alternatives.

The fiber discussion is conspicuously absent. While fiber is not a traditional nutrient deficiency, most Americans eat only about 15 grams per day against a recommendation of 25-30 grams. On a reduced-calorie diet, hitting fiber targets becomes even harder, and the constipation that many GLP-1 users experience is directly related to inadequate fiber and water intake.

Questions for Your Doctor

Before starting or during your next appointment while on GLP-1 medication, ask for a baseline nutritional panel including iron studies (more than hemoglobin), vitamin D, B12, folate, and calcium. Ask about whether a high-quality multivitamin makes sense as a safety net. If you are experiencing hair loss, ask about checking ferritin (stored iron) and zinc levels specifically. And ask about protein targets given your weight and activity level.

A Practical Supplement Strategy for GLP-1 Users

Most GLP-1 users benefit from a targeted supplement strategy. This is not about buying every vitamin on the shelf. It is about covering the specific gaps that reduced food intake creates. A reasonable baseline includes: a high-quality multivitamin taken with food (not on an empty stomach, which worsens nausea), vitamin D3 at 1,000-2,000 IU daily (higher if blood levels are low), magnesium glycinate at 200-400mg daily (helps with muscle cramps, sleep, and constipation), and omega-3 fish oil at 1,000-2,000mg daily for heart health and inflammation reduction.

Protein supplementation bridges the most critical nutritional gap. A daily protein shake using whey, casein, or plant-based protein powder can add 20-30 grams of protein with minimal volume and effort. For people experiencing meat aversions (common on GLP-1 medications), protein powder becomes nearly indispensable for hitting daily targets. Look for a product with minimal added sugar, at least 20 grams of protein per serving, and a flavor you actually enjoy drinking. The best protein powder in the world is useless if it sits unopened in your pantry because you hate the taste or the texture makes you gag.

Collagen supplements have gained popularity among GLP-1 users concerned about skin elasticity during rapid weight loss. Some studies suggest 5-15 grams of collagen peptides daily may improve skin elasticity and hydration. While collagen should not count toward your primary protein target (it lacks essential amino acids like leucine needed for muscle protein synthesis), it can be a useful addition if skin health is a concern. Add it to your morning coffee or smoothie for easy integration into your daily routine without any extra effort or thought.

Supplement timing matters for absorption and tolerance. Fat-soluble vitamins (A, D, E, K) absorb better when taken with a meal containing fat. Iron absorbs better with vitamin C and away from calcium and dairy. Magnesium is often best taken at bedtime for its mild sleep-promoting effects. And B vitamins are best taken earlier in the day since they can be mildly stimulating for some people. Setting up a simple morning and evening supplement routine with these timing considerations builds the habit without overcomplicating your day or adding another source of decision fatigue to your already-changed eating routine on GLP-1 medication.

Who Should Watch This Video

Every current GLP-1 user should watch this, especially people who have been on medication for more than three months without having bloodwork done. People who are about to start a GLP-1 medication can use this to set up proper monitoring from the beginning. And anyone experiencing unexplained fatigue, hair loss, muscle cramps, or weakness while on these medications should watch this as a potential explanation for their symptoms.