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What Ozempic Won’t Do for Your Metabolic Health

Date:


In this episode we discuss:

  • How GLP-1 drugs work 
  • Proven benefits, common side effects, and discontinuation rates
  • Emerging long-term risks of GLP-1 use
  • The risk of nutrient deficiencies from reduced food intake
  • Muscle loss & body composition changes
  • Weight regain after discontinuing use
  • The lack of root-cause treatments addressing diet, lifestyle, and metabolic drivers
  • Who benefits most from GLP-1s vs. who may not
  • Using GLP-1s as part of a broader health strategy

Show notes:

Hey everybody, Chris Kresser here. Welcome to another episode of Revolution Health Radio. GLP-1 receptor agonists like Ozempic, Wegovy, and Munjaro are the most talked about medications in modern medicine right now, and the conversation is almost uniformly positive.

One in five American adults has now used these drugs, prescriptions have grown dramatically since 2019, and the media coverage treats them as a straightforward breakthrough. A lot of that enthusiasm is earned, and I want to be clear about that up front. The weight loss data in clinical trials is real. The cardiovascular benefits in high risk patients are meaningful, and I understand why millions of people are drawn to them. But the picture is more complicated than what most people are hearing, and the research is catching up in ways that should change the conversation. A 2026 systematic review and meta-regression from Cambridge, published in eClinicalMedicine and covering 48 studies and over 3000 participants, modeled exactly what happens to weight after people stop these drugs. The findings are not what the headline suggests. At the same time, new data on side effects, including findings presented just this month at the American Academy of Orthopedic Surgeons annual meeting, are filling in gaps that weren’t visible in the original trials.

I’ve followed the GLP-1 research closely since these drugs started gaining mainstream traction, and my core question has always been the same. Do they work over the long term? Does the weight loss persist after people stop taking them? And if it doesn’t, what are the risks of being on these medications indefinitely? As that research has accumulated, a second concern has grown alongside it. From a functional medicine perspective, these drugs don’t address the root causes of obesity and overweight, which are complex and multifactorial. The idea that we can resolve a mismatch between our genes, our biology, and our environment with a single class of medications reflects the kind of magic bullet thinking that has repeatedly led medicine astray. None of this is meant to judge anyone who’s taking these drugs or who has taken them. The appeal is understandable, and I want this episode to reflect that. But informed consent requires the full picture, and by the end of this episode, you’ll have it – what GLP-1s actually do, the emerging side effect data as longer term follow up arrives, what the rebound data tells us about whether these drugs produce durable change, the nutrient depletion and lean mass concerns that most prescribers aren’t discussing, and what a root-cause framework tells us about who these medications may genuinely help. Let’s dive in.

What GLP-1s Actually Do, and the Genuine Benefits

Let’s start with the basic science. GLP-1, glucagon-like peptide-1, is a hormone your gut releases naturally after eating. It signals the brain to reduce appetite, stimulates the pancreas to release insulin, suppresses glucagon, and slows gastric emptying so you can feel full longer. GLP-1 receptor agonists like semaglutide mimic that hormone at pharmacological doses, substantially higher than your body would naturally produce. In clinical trials, the weight loss is real and substantial. Semaglutide produces roughly 15 percent average weight loss, and tirzepatide, which adds a second hormonal mechanism targeting the glucose-dependent insulinotrophic polypeptide receptor, reaches around 18 to 20 percent in the strongest trials. For patients with Type II diabetes, the glycemic benefits are well documented. The SELECT cardiovascular outcomes trial showed meaningful reductions in major cardiovascular events in high risk patients with obesity and established cardiovascular disease. There’s also emerging evidence of benefits in chronic kidney disease, and in heart failure with reduced ejection fraction. These are real drugs producing real effects in real patients with serious conditions. I want to be absolutely clear about that before we go further, because this episode is not about dismissing the science or the people who’ve benefited. The question isn’t whether GLP-1s work in the short term. They clearly do. The questions worth asking are what happens beyond the clinical trial window, who actually belongs on them long term, and what’s being systematically left out of the mainstream conversation.

The Side Effect Profile the Mainstream is Largely Glossing Over

The most common side effects are gastrointestinal. Nausea, vomiting, diarrhea, and constipation affect the majority of users, and they’re the primary driver of discontinuation. Roughly half of all patients who start GLP-1 therapy stop within the first year, largely because of these symptoms, combined with cost and insurance barriers. That’s a number worth reflecting on. We talk about these medications as transformative, but half the people who start them don’t stay on them long enough to see their full effect. Beyond the GI symptoms, a more complex picture is emerging as longer term data arrive. One issue that’s received serious clinical attention is surgical risk. Because GLP-1s significantly delay gastric emptying, patients on these drugs face elevated aspiration risk during anesthesia. The American Society of Anesthesiologists recommends stopping short acting formulations at least one day before surgery, and long acting formulations at least a week prior. The problem is that a 2024 cross-sectional study found 56 percent of patients still had elevated residual gastric contents even after stopping for seven or more days, which raises real questions about whether that guidance provides adequate protection.

There’s also an emerging signal around pancreatitis. The UK and Brazil have both issued formal warnings. A 2025 meta-analysis of 62 randomized controlled trials found a slightly elevated risk compared to placebo, though other large analyses have found no association. So the evidence remains contested. What isn’t contested is that the signal exists and that it belongs in the informed consent conversation.

Psychiatric concerns have also drawn regulatory attention. The European Medicines Agency opened an inquiry in 2023 after about 150 spontaneous reports suggesting possible links between GLP-1 drugs and suicidal ideation. A World Health Organization database analysis identified a signal specifically for semaglutide, notably absent for liraglutide, and the signal was particularly pronounced in patients also taking antidepressants. Subsequent cohort studies have produced mixed results, and causality has not been established. But this is the kind of signal that should be surfaced proactively with patients.

The most striking new data comes this month from the 2026 annual meeting of the American Academy of Orthopedic Surgeons. Researchers presented a five-year retrospective cohort study matching 73,000 patients on GLP-1 receptor agonists against controls balanced for age, sex, BMI, and baseline comorbidities. After five years, GLP-1 users showed significantly higher rates of three musculoskeletal conditions. A 29 percent higher risk of osteoporosis, a 12 percent higher risk of gout, and the most striking finding was a 155 percent higher relative risk of osteomalacia, a rate of 2 percent in GLP-1 users versus 0.1 percent in matched controls. Osteomalacia is a bone softening condition caused by severe vitamin D and calcium deficiency. When I saw those numbers, I was alarmed, but not entirely surprised, because they connect directly to what the nutrition data has been showing, which we’ll come to in a moment. For balance, the same AAOS conference presented a second study showing GLP-1 use was associated with better short-term outcomes across 10 common orthopedic procedures, including lower rates of surgical site infections after knee and hip replacements and fewer post-operative emergency department visits. The short-term benefits, again, are real. It’s the long-term picture that deserves a lot more scrutiny than it’s currently getting.

GLP-1 receptor agonists like Ozempic are transforming the landscape of weight loss and metabolic health—but are they the complete solution they’re often made out to be? These medications manage symptoms, not root causes, and lasting metabolic health requires more than a prescription. #ChrisKresser #GLP-1

The Nutrient Depletion Problem

I’ve written and spoken extensively about baseline nutrient deficiency in the developed world, and I’ll put a link to some of the previous articles in the show notes. Even before anyone takes a GLP-1, a significant portion of the population is already deficient in vitamin D, magnesium, B12, iron, and other critical nutrients. These are not optional nutrients. They underpin immune function, neurological health, bone density, energy metabolism, muscle maintenance, and much more. We are not starting from a position of nutritional abundance. GLP-1 receptor agonists substantially suppress appetite, which means users eat significantly less. That’s not just fewer calories, it’s fewer nutrients across the board.

A 2025 cross-sectional study published in Frontiers in Nutrition looks specifically at what GLP-1 RA users were actually eating, compared against dietary reference intakes. The findings were disturbing. Participants fell below recommended levels for fiber, calcium, iron, magnesium, potassium, choline, and vitamins A, C, D, and E. Protein intake, while acceptable as a percentage of total calories, was significantly below the daily requirement per kilogram of body weight during active weight loss, a gap that matters enormously for preserving muscle. A large retrospective analysis published in Obesity Pillars in 2025 pulled data from over 460,000 GLP-1 RA users. Within six months of starting, almost 13 percent had been diagnosed with a nutritional deficiency. Within 12 months, that number had risen to 22 percent. And nearly 92 percent of those patients with no documented dietician involvement before starting the medication. I want to emphasize here that this bar for nutrient deficiency is pretty high in the conventional paradigm. I’ve argued in the past that the reference ranges in the conventional or mainstream medical model are too broad for nutrients, and in fact if we used tighter, more optimal reference ranges, we would actually see much higher rates of deficiency in the general population and deficiency in these studies of GLP-1 users. So it’s almost certain that the rates of nutrient deficiency were underestimated here, as high as they already were. So we’re prescribing these drugs at enormous scale with almost no nutritional support infrastructure around them.

A 2026 review in Clinical Obesity documented that vitamin D deficiency rates rose from seven and a half percent at six months to almost 14 percent at 12 months, along with escalating thiamin and B12 deficits over time. The review also found more serious cases through case reports.  Wernicke’s encephalopathy and dry beriberi, which are caused by severe thiamine deficiency, have been linked to semaglutide use. Again, these are not theoretical risks. They’re documented outcomes in real patients. The osteomalacia signal from the AAOS five-year data fits this pattern directly. Osteomalacia is the clinical consequence of chronic, severe vitamin D and calcium deficiency, and it’s showing up at a rate 20 times higher in GLP-1 users than in matched controls. The nutrition data predicts exactly that.

Muscle Loss and What It Means for Aging

The lean mass question is related to nutrient depletion but worth addressing separately, because the implications for aging are in their own category. Preserving muscle mass as we get older is one of the most powerful predictors of health, function, and longevity we have. Muscle isn’t just cosmetic. It’s metabolically active tissue that protects against insulin resistance, supports bone density, reduces fall risk, and determines whether people retain independence as they age. GLP-1s appear to be eroding it in ways the field is still working to understand. In the original STEP 1 trial data for a semaglutide, approximately 45 percent of total weight loss was lean mass, exceeding the roughly 25 percent that conventional weight loss research would predict from caloric restriction alone. A 2025 network meta-analysis published in Metabolism, covering 22 randomized controlled trials and over 2200 participants, confirmed that tirzepatide and semaglutide were among the least effective GLP-1 agents for preserving lean mass, the very agents showing the greatest weight loss. A 24-month retrospective study in older adults with Type II diabetes found semaglutide accelerated physiological muscle decline, particularly at higher doses and in patients who are already starting from a low muscle mass baseline.

The science here isn’t completely settled. Some analyses using MRI-based body composition measures suggest the muscle changes are “adaptive,” proportional to what any significant weight loss would produce, rather than pathologically excessive. That framing is more reassuring and it’s worth acknowledging, but the concern sharpens considerably in older populations, where up to half of adults over 80 are already sarcopenic, meaning lacking in muscle mass. For people already near a functional threshold, even a modest additional loss of muscle can tip them into frailty, falls, and fractures. Combined with the bone density findings from the AAOS five-year data, those risks compound. What clearly mitigates lean mass loss is resistance training combined with adequate protein intake, and the evidence on this is consistent. What’s also consistent is that most prescribers aren’t emphasizing it, and most patients aren’t doing it. Almost none of the major trials incorporated structured resistance training as a co-intervention, which means the field’s efficacy data reflects outcomes in people who largely weren’t doing the one thing that could protect their muscle.

The Rebound: What the Best Data Now Shows

The question I’ve had about these drugs from the beginning is whether the weight loss persists after people stop taking them. Given that roughly half of all users discontinue within the first year, this isn’t a narrow edge case. It describes the majority of real world experience with GLP-1 therapy. The most rigorous answer to date comes from a 2026 systematic review just published in eClinicalMedicine by researchers at Cambridge. Unlike earlier reviews that reported single point-in-time estimates of weight regain, this study modeled the full trajectory using data from 48 studies, including six high-quality randomized controlled trials with over 3000 participants. The trajectory follows a predictable exponential curve – rapid initial regain, decelerating, then plateauing. At one year after stopping, approximately 60 percent of the weight lost during treatment had been regained. The model extrapolated a plateau at around 75 percent of original weight loss, with a half-life of 23 weeks, meaning the typical patient regains half their drug-induced weight reduction within about six months of stopping. An earlier meta-analysis of eight randomized trials found that patients stopping semaglutide or tirzepatide specifically regained an average of nearly 10 kilograms after discontinuation.

There is a genuinely important nuance here I want to make sure doesn’t get lost. The Cambridge model also found that roughly 25 percent of the initial weight loss may persist long term, corresponding to approximately a four to 5 percent net reduction in body weight from baseline. That’s a modest but real benefit that may persist even years after stopping. And some cardiometabolic markers showed partial durability as well. If someone can achieve that four to 5 percent sustained reduction through a short course of GLP-1 therapy and then maintain it through lifestyle change, that’s a reasonable outcome worth considering.

But the broader pattern is clear, and it has a straightforward biological explanation. These drugs work by pharmacologically suppressing appetite signaling. When you stop taking them, that suppression ends. The underlying hunger physiology returns unchanged, because the root conditions that drove it, whether gut dysbiosis, insulin resistance, chronic stress, sleep disruption, or some combination haven’t been touched. The drug managed the symptom while it was active. When it wasn’t, the symptom came back.

There’s also a body composition dimension to the rebound that rarely gets discussed. The weight that returns after stopping comes back primarily as fat mass, not lean mass. Patients who end up with a net lower body weight than before they started may nonetheless have worse body composition than if they had never taken the drug – less muscle, proportionally more fat. The Cambridge paper specifically flagged this as a critical gap in the research that future trials need to address, because no studies have yet systematically tracked body composition changes after discontinuation.

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The Root Cause Blind Spot

This brings me to what I consider the central limitation of GLP-1 therapy, and the pattern I’ve watched repeat throughout my career in functional medicine. Obesity and overweight are not diseases of deficient GLP-1 signaling. They’re complex, multifactorial conditions that emerge from a profound mismatch between our biology and the environment we’ve constructed – ultra-processed food engineered to override satiety signals, sedentary patterns our physiology never evolved for, chronic stress that dysregulates cortisol and disrupts hunger hormones, sleep deprivation that increases ghrelin and suppresses leptin, environmental toxins that interfere with metabolic function, gut dysbiosis that affects both nutrient absorption and systemic inflammation, and the interaction of all those factors with individual genetic and hormonal variation. No single drug or class of drugs can address that kind of complexity.

What GLP-1s do is suppress one branch of the appetite signaling system powerfully while you’re taking them, and temporarily in most cases. They don’t restore gut microbiome ecology. They don’t address insulin resistance at the cellular level. They don’t reset HPA axis dysregulation from chronic stress. They don’t improve sleep architecture. They don’t reduce the inflammatory burden from poor diet quality. They don’t replete the micronutrients that were already inadequate before treatment began. They suppress appetite. That’s meaningful, but it’s a fraction of what needs to change for most people to achieve durable metabolic health. The Magic Bullet thinking that treats GLP-1s as a solution rather than a partial, temporary intervention is not new to medicine. It has a long history, and that history should make us careful.

None of this means these medications have no place. The risk-benefit calculation looks genuinely different depending on who we’re talking about. For someone with established cardiovascular disease, Type II diabetes, and obesity, the SELECT trial data and the cardiorenal outcomes research present real, meaningful benefits that may justify long-term use in spite of the side effect profile. That’s a legitimate clinical judgment. The picture is considerably less clear for younger adults without metabolic comorbidities using these drugs primarily for cosmetic weight loss, or for anyone who would require indefinite use to avoid full rebound, especially now that we have five-year bone data, longitudinal nutrition data, and a clearer trajectory of what happens when people stop. Personally, I wouldn’t have recommended these drugs to my patients in most cases, and I wouldn’t recommend them to family members. But I recognize there may be specific cases where the calculus is different.

The people most likely to get something durable from GLP-1 therapy are those who use the window of appetite suppression to systematically change the conditions that drove the weight gain in the first place – improving diet quality rather than just quantity, building resistance training into their routine, addressing sleep and stress, supporting gut health, and ensuring through proper nutritional assessment, they’re not quietly depleting the micronutrients their muscles and bones depend on. The drugs won’t do any of that. They’re creating a window in which that work can happen. Whether it does depends almost entirely on what surrounds them.

And here’s what I find frustrating about how these medications are being prescribed and discussed right now. That window is going largely unused. Close to 92 percent of real world GLP-1 users have no dietitian involvement. Resistance training is almost never emphasized as a co-requirement. Root cause investigation of gut health, hormonal status, sleep, stress, and nutritional deficiency is rarely part of the conversation. The drug is being sold as the answer when the evidence increasingly shows it’s, at best, one useful tool in a much larger strategy that most patients aren’t receiving. We’re at a moment in medicine when powerful pharmacological tools arrive faster than our wisdom about how to use them. That’s not an argument against the tools. It’s an argument for the wisdom. GLP-1 medications are not metabolic repair, they’re metabolic management. And that distinction matters enormously for anyone making a long-term decision. The patients who will do best with these medications are the ones who treat them as one piece of a complete strategy, not the whole answer.

Thanks for listening, everyone. You can find show notes and links to all the studies I mentioned at ChrisKresser.com. If you have any questions about this episode or suggestions for future topics, head over to ChrisKresser.com/podcastquestion and leave me a message. I read all of them, and your questions help shape the content I create, including this very episode. Until next time, be well.



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