Video: What Your Doctor Isn't Telling You About Ozempic

Millions of people are on Ozempic, Wegovy, Mounjaro, and losing weight. And honestly, some that weight loss is genuinely impressive. But here's what almost nobody is telling patients before they start. More than one in five people on these drugs develop a measurable nutritional deficiency within the first year. One in five. And that's from a study of nearly half a million people. So today we're going to talk about what GLP-1 drugs are actually doing to your body nutritionally and what you can do to protect yourself. If you're new here, welcome. I'm Dr. Mark Stengler and I practice integrative medicine. I work with patients every day who are on these medications and I wanted to give you the honest nuanced picture that you're probably not getting from a 10-minute office visit. This isn't an anti-GLP-1 video. These drugs can have real benefits, but they also have real risks and nutritional depletion is one of the biggest ones flying under the radar. So let's get into it. First, a quick primer. GLP-1 receptor agonists, drugs like semaglutide, which is Ozempic or Wegovy, and tirze- peptide, which is Mounjaro or Zepbound, work by mimicking a hormone your gut naturally releases after you eat. That hormone does a few things. It slows down how fast your stomach empties. It also tells your brain you're full and it dramatically suppresses your appetite. The result, people eat 30 to 50% fewer calories than they normally would. For weight loss, that's the mechanism. But here's where the problem starts. When you suppress appetite that powerfully, the body doesn't selectively stop wanting junk food. It stops wanting all food including the lean protein, the leafy greens, the eggs, the fish, all the nutrient-dense foods your body depends on. So you're losing weight, yes, but you may also be losing critical vitamins, minerals, and muscle right along with it. In 2025, a landmark study by Butch and colleagues was published in the journal Obesity Pillars. And when I saw these numbers, it really drove home how significant this problem is. The researchers looked at the medical records of 461,382 adults, almost half a million people who were newly prescribed GLP-1 drugs between years 2017 and 2021. None of them had pre-existing nutritional deficiencies when they started. Here's what they found in the study. Nearly 13% developed a nutritional deficiency within just 6 months. Over 22%, more than one in five, developed one within 12 months. And here's the part that really stood out to me as a clinician. Patients who saw a dietitian in those first 6 months were more likely to have deficiencies identified and addressed, which means for everyone else, these deficiencies go undetected. That's not acceptable and it's exactly why I monitor my patients' blood levels closely when they're on these drugs. Of all the nutritional risks here, inadequate protein is the one I worry about most. Here's why. When your body is losing weight fast and not getting enough protein, and remember the general recommendation during active weight loss is about 1.2 to 1.6 g of protein per kilogram of body weight, it starts breaking down lean muscle to get the amino acids it needs. Research on semaglutide has shown that a significant portion of the weight loss can be lean mass, not just fat. And this isn't just a cosmetic concern. We're talking about the loss of muscle strength, reduced metabolic rate, which makes weight regain more likely when the drug is stopped, increased risk of frailty, falls, and bone fractures, especially in older adults. Sarcopenia. This is the progressive, dangerous loss of muscle that is very hard to reverse. So, if you're on one of these medications and you're not actively prioritizing protein at every single meal, this is a wake-up call. Let's walk through the specific nutrients I see depleted most often in my GLP-1 patients. Let's start with vitamin B12. GLP-1 drugs slow gastric emptying and reduce activity in the stomach lining. That matters because the stomach produces something called intrinsic factor, which is required to absorb B12. When that process is disrupted, B12 levels quietly drop. And the symptoms, like fatigue, brain fog, nerve tingling, and anemia can creep up slowly over months before anyone connects the dots. Let's talk about iron. Iron absorption depends on stomach acid and happens primarily in the upper small intestine. When gastric or stomach activity is reduced and food transit is altered, iron absorption takes a hit. Iron deficiency is one of the most common deficiencies I see and it's a major driver of fatigue and poor recovery. Zinc's also very important because it's critical for immune function, wound healing, and hormone regulation. People on GLP-1 drugs tend to gravitate towards small, soft, easy to tolerate foods. Things like crackers, yogurt, and smoothies. These foods tend to be in low in zinc and over time that adds up and people end up with zinc deficiency. Then there's the fat-soluble vitamins A, D, K, and E. Meaning they require dietary fat to be absorbed. When overall food intake drops and dietary variety narrows, these are often the first to fall short. Vitamin D deficiency is already epidemic in the general population and GLP-1 drugs can deepen that deficit substantially. And here's why that matters beyond just low vitamin D. Vitamin D works together with calcium and magnesium to maintain bone density. So if all three are falling short simultaneously, you're accelerating bone loss. Especially dangerous in postmenopausal women and men over the age of 60. Electrolytes are also important, especially magnesium. GLP-1 drugs commonly cause nausea, vomiting, and diarrhea. Particularly during dose escalation. Every time that happens, you're losing potassium, sodium, and magnesium. But magnesium alone is involved in over 300 biochemical processes low magnesium looks like muscle cramps, heart palpitations, poor sleep, and feeling wired but exhausted at the same time. Magnesium deficiency is very common and extremely underdiagnosed. Now let's talk about who's most at risk. Not everyone on a GLP-1 drug carries the same risk, but certain groups need to be especially vigilant. Adults over the age of 60 because they already have reduced absorption efficiency for many nutrients and there's less muscle reserve to begin with. The margin for error is smaller in these people. For postmenopausal women, bone health risks compound significantly when calcium, D, and magnesium are all falling short during rapid weight loss. People starting with pre-existing deficiencies, this is also a major problem. It's common in obesity, type 2 diabetes, and metabolic syndrome. Starting a GLP-1 drug without addressing baseline deficiencies sets people up for rapid deterioration. People who aren't eating protein, whether due to nausea, food aversion, or simply not knowing better, eating tiny portions of soft, low-protein food is a fast track to muscle loss. So, what can we do about this? This is the part I really want you to walk away with. These risks are manageable. They're not a reason to avoid these medications if they're right for you, but they are reason to be proactive. First, prioritize protein at every meal. Aim for at least 25 g per meal. Best food sources are like eggs, Greek yogurt, cottage cheese, fish, chicken, and lean meats. If your appetite is too suppressed to hit those numbers with food alone, a high-quality protein powder is highly recommended. Second, consider targeted supplementation. At our clinic, we commonly recommend a few specific supplements for patients on GLP-1 drugs. First, we recommend a multivitamin. A high-quality, comprehensive multivitamin is needed to cover the basic micronutrient needs. Next, creatine. Creatine helps to preserve lean muscle mass and support strength during active weight loss. This is what I feel really strongly about. Also, vitamin D3 with K2. D3 supports calcium absorption. K2 directs calcium into bones and away from arteries. And most GLP-1 patients need this combination. Remember, it's also important to move your muscles. Resistance exercise, such as weight training, resistance bands, body weight exercises are non-negotiable if you want to preserve muscle while losing weight on these drugs. Aim for two to three sessions per week at minimum. Remember, this is not optional. Also, have your labs checked. Ask your doctor to check your vitamin B12, your vitamin D, iron, your iron stores known as ferritin, zinc, magnesium, and a full metabolic panel, ideally before you start a GLP-1 drug and every 3 to 6 months while on it. If your doctor isn't monitoring these, advocate for yourself. GLP-1 drugs are a powerful tool, but like any powerful tool, they need to be used with awareness and care. The bottom line, if you or someone you love is on one of these medications, nutrition's not an afterthought, it is part of the treatment plan. If you found this helpful, please like and subscribe. I cover integrated and functional medicine topics like this every week. If you have any questions or want to share your experience with GLP-1 drugs, drop them in the comments below. I read them as do my staff. Well, see you in the next video.

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