Semaglutide (sold as Ozempic for diabetes and Wegovy for weight management), tirzepatide (Mounjaro and Zepbound), and a growing number of compounded alternatives have produced weight loss results that most physicians, myself included, did not think were pharmacologically possible five years ago.
The trial data is striking. In STEP 1 (Wilding and colleagues, New England Journal of Medicine, 2021), adults on weekly semaglutide 2.4 mg lost an average of 14.9% of body weight over 68 weeks, against 2.4% on placebo. In SURMOUNT-1 (Jastreboff and colleagues, New England Journal of Medicine, 2022), the highest dose of tirzepatide produced an average 20.9% loss over 72 weeks. And the effects reach past the scale: in the SELECT trial (Lincoff and colleagues, New England Journal of Medicine, 2023), semaglutide cut the rate of cardiovascular death, heart attack and stroke by 20% relative to placebo in people with existing cardiovascular disease and obesity or overweight.
So yes. These drugs work, in the populations that were studied.
The problem is not the medication. It is how many people are getting it.
Online clinics and subscription telehealth services have turned GLP-1 prescribing into a consumer product. Fill out a form, get a script, inject weekly, check the scale. That convenience has helped a lot of people access treatment who might not have otherwise. It has also created a situation where powerful drugs are being used with almost no medical guardrails.
The consequences do not announce themselves until real damage is done.
GLP-1 stands for glucagon-like peptide-1, a gut hormone your body makes after meals. It triggers insulin secretion when glucose is present, dials down glucagon, slows gastric emptying so you feel full longer, and acts on appetite centers in the brain.
GLP-1 receptor agonists turn that signal up far beyond what your body produces on its own. Tirzepatide adds a second lever by also activating GIP (glucose-dependent insulinotropic polypeptide) receptors.
The practical result: you eat less, your blood sugar stabilizes, and you lose weight. But these drugs are talking to your pancreas, your gut, your brain and your gallbladder all at the same time. That is why a questionnaire and a monthly subscription are not enough.
The typical direct-to-consumer experience looks something like this:
What does not happen: baseline bloodwork. Body composition testing. Ongoing lab monitoring. Nutrition guidance. Exercise programming. A relationship with a physician who actually knows your case.
On compounded products specifically: the FDA states plainly that compounded drugs are not FDA approved and are not reviewed for safety, effectiveness or quality before they are marketed. As of May 31, 2026, the agency had received 990 adverse event reports tied to compounded semaglutide and more than 730 tied to compounded tirzepatide, including hospitalizations that may relate to dosing errors with compounded injectables (FDA, "FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss").
The polite term for the low-touch model is "convenient." The accurate term is dispensing.
When these medications are managed properly, the side effect profile is manageable for most people. When they are not, problems compound.
This is the risk that does not get nearly enough attention.
Rapid weight loss from any cause pulls muscle along with fat. A 2026 systematic review in the Annals of Internal Medicine (Batsis and colleagues) pooled 35 randomized trials of semaglutide, tirzepatide, liraglutide and dulaglutide and found that the median share of total weight lost that came from muscle-related measures was 28.3%, with a wide range across studies (roughly 16% to 40%), and that two thirds of studies exceeded the expected benchmark for muscle loss. Not one of those trials measured whether patients could actually function better afterward.
I need that number to land. If you lose 40 pounds and 11 of them are muscle, you have done something your body cannot easily undo. Muscle drives your metabolic rate, protects your joints, maintains bone density, and is one of the strongest predictors of how well you will function at 70 or 80. We have written about why this matters in our guide to healthspan vs. lifespan.
Lose significant muscle and your resting metabolic rate drops, which sets the stage for regain. Sarcopenia accelerates, especially past 40. Bone density tends to follow. You look lighter on the scale. But you are weaker, more fragile and metabolically worse off than when you started.
This is not inevitable. Resistance training and adequate protein are the two biggest levers for holding onto lean mass during weight loss. But you need a structured plan, someone tracking your body composition, and someone checking more than your weight. The typical online clinic gives you none of that.
When appetite drops sharply, nutrient intake drops right along with it. Most patients on GLP-1s are not eating enough protein to maintain muscle mass. B12 is a good example of a marker that starts marginal and gets worse: Allen (American Journal of Clinical Nutrition, 2009) reviewed large U.S. and U.K. surveys and found about 6% of adults over 60 are B12 deficient and closer to 20% have marginal status. Iron drops, especially in women. Magnesium, vitamin D, calcium all decline when you are eating a fraction of what you used to.
I have seen patients come in three months into unsupervised GLP-1 use with B12 levels that explained their fatigue and brain fog better than anything else. They thought the medication was making them tired. It was what they had stopped eating.
A registered dietitian designing meals around nutrient density inside a drastically reduced appetite is not a luxury during GLP-1 therapy. It is a clinical necessity. It is also why we believe the right lab tests matter so much. You cannot manage what you do not measure.
Nausea, vomiting, diarrhea and constipation are the most common adverse reactions on the Wegovy label, and most people who get them during dose escalation find them tolerable and temporary.
The less common complications are not tolerable at all.
Sodhi and colleagues (JAMA, 2023) followed patients prescribed semaglutide or liraglutide for weight loss and compared them with patients on a non-GLP-1 weight-loss drug. GLP-1 use was associated with roughly nine times the rate of pancreatitis, nearly four times the rate of gastroparesis (a stomach that empties dangerously slowly), and about four times the rate of bowel obstruction. He and colleagues (JAMA Internal Medicine, 2022) pooled 76 randomized trials and found GLP-1 drugs raised the risk of gallbladder and biliary disease by 37% overall, and by more than double in trials run for weight loss. The Wegovy prescribing information carries specific warnings for acute pancreatitis, acute gallbladder disease and severe gastrointestinal adverse reactions.
A physician who is tracking your symptoms and labs catches these problems early. An automated refill system catches nothing.
Wegovy carries a boxed warning, the FDA's most serious category, about thyroid C-cell tumors, based on rodent studies. Whether the same risk exists in humans is unknown, and that uncertainty is exactly why the drug is contraindicated in anyone with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2.
Proper prescribing means a real family history and a real conversation about thyroid symptoms. Not a checkbox on a web form.
This one is harder to quantify, but I think it is just as important.
GLP-1 drugs act on appetite and reward centers in the brain. Some patients describe losing not just hunger but the enjoyment of eating entirely. Social withdrawal around meals. Mood shifts they cannot explain. The Wegovy label instructs prescribers to monitor for depression and suicidal thoughts. For anyone with a history of disordered eating, extreme appetite suppression can trigger or reactivate restrictive patterns that took years to manage.
A physician who sees you regularly, who actually knows you, notices these changes. That continuity of care is something no algorithm replaces.
If you are on a GLP-1 or considering one, talk to us about doing it with proper oversight.
We treat these as the serious medications they are. Whether a GLP-1 is right for you is a decision your physician makes with you, based on your history and your labs. Nobody at Rebel prescribes off a form. Here is what the process looks like when it is appropriate.
Comprehensive bloodwork comes first. Metabolic panel, liver and kidney function, a full thyroid panel, lipids, HbA1c, fasting insulin, inflammatory markers, B12, vitamin D, iron, magnesium. A body composition baseline via DEXA or equivalent (a cash-pay add-on): lean mass, fat mass, visceral fat. Not a scale reading.
Then you and your physician sit down on a virtual visit. Family history of thyroid cancer, pancreatitis, gallbladder disease. Eating disorder history. Current medications and contraindications. Goals that go beyond "lose X pounds," because weight is a lagging indicator of metabolic health, not a complete picture of it.
If you want to see the full range of biomarkers we track, we have laid it out in our guide to the blood tests your doctor isn't running.
Your physician starts low and titrates based on your tolerance and your labs, not a corporate dosing schedule.
Bloodwork is rechecked on the schedule your physician sets: metabolic markers, liver enzymes, thyroid, nutritional status, hormones. Body composition is tracked over time. If lean mass loss is running too high, the protocol changes. Protein targets go up. Training gets modified. And the dose comes down if that is what the data says to do.
On Rebel Peak, a registered dietitian builds your nutrition plan around a protein target set for your lean mass and your training. The research supports intakes well above the RDA: Phillips and colleagues (Applied Physiology, Nutrition, and Metabolism, 2016) put the range for optimal health at 1.2 to 1.6 grams per kilogram of body weight per day, and Morton and colleagues (British Journal of Sports Medicine, 2018) found no further muscle gains from protein above about 1.6 grams per kilogram in people doing resistance training. Where you land inside that range is a decision for your dietitian and physician, not a number off the internet.
A certified strength coach programs resistance training, typically three to four sessions a week, specifically to protect lean tissue during pharmacological weight loss. On Rebel Health, the physician-only membership, your physician sets the same targets and you can add coaching sessions a la carte.
And you see the same physician. Every time. You can message your team anytime; replies usually land the same day.
Honestly, this might be the most neglected part of GLP-1 therapy in all of medicine right now.
In the STEP 1 extension (Wilding and colleagues, Diabetes, Obesity and Metabolism, 2022), participants who stopped semaglutide regained two thirds of the weight they had lost within a year, and most of their cardiometabolic improvements drifted back toward baseline with it. Two thirds. If you do not have a plan for what happens after the prescription, you are renting results.
Some patients should stay on GLP-1 medication long term. That is a legitimate medical decision made with a physician. For those who want to come off, it takes a structured taper and the nutrition, training and sleep habits that make results stick without the drug. We build that exit strategy from day one.
A compounded subscription is cheaper per month than brand-name treatment with real oversight. That is the whole pitch.
If you spend a year on the cheap route and lose 40 pounds but a third of it is muscle, here is what you actually bought: a lower resting metabolic rate, weaker bones and joints, and a body primed to regain fat rather than muscle. Muscle loss is what drives frailty more than anything else.
The cheapest prescription becomes the most expensive mistake when nobody is watching what it is doing to your body.
Whether you work with us or someone else, do not accept a prescription without real answers to these:
If the provider cannot answer all six, find one who can.
GLP-1 medications are a genuine advance in how we treat obesity, metabolic syndrome and type 2 diabetes. For the right patients, they deliver weight loss and metabolic improvement that few other interventions can match.
But a drug this powerful does not belong in a subscription box. It belongs in a medical relationship, with labs, coaching, monitoring and a long-term strategy.
A prescription is not a plan. Let us build you one.
Book a 20-minute call to talk with our physician-led team about GLP-1 therapy done right.
Do I need a doctor for GLP-1 medications like Ozempic or Wegovy?
Legally, you need a prescription, which means some form of provider interaction. But "need a doctor" and "need a questionnaire rubber-stamped by someone with prescribing authority" are very different things. For a medication that affects your pancreas, gut, brain and gallbladder at once, physician oversight with regular lab monitoring is the responsible minimum.
What tests should I get before starting a GLP-1?
At minimum: a comprehensive metabolic panel, liver and kidney function, a thyroid panel, lipids, HbA1c, fasting insulin, B12, vitamin D, iron and magnesium, plus a body composition baseline (not just a scale). If your provider does not offer this, that tells you something.
Can I prevent muscle loss while taking semaglutide or tirzepatide?
You cannot eliminate it, but you can reduce it substantially. Resistance training several times a week and a protein target set by a dietitian for your lean mass are the two biggest levers. Batsis and colleagues (2026) found muscle accounted for a median 28% of weight lost on these drugs in trials, most of which had no structured training component.
How much weight comes back after stopping a GLP-1?
In the STEP 1 extension (Wilding and colleagues, 2022), participants regained two thirds of their lost weight within a year of stopping semaglutide. A structured taper with exercise and nutrition habits already in place improves those odds. Stopping cold is not a plan.
Is compounded semaglutide safe?
Compounded drugs are not FDA approved and are not reviewed for safety, effectiveness or quality before sale. The FDA has logged hundreds of adverse event reports for compounded semaglutide and tirzepatide, including hospitalizations that may relate to dosing errors. If you use a compounded product, physician oversight matters even more.
See what your own labs would show.
A physician you can message any time, an initial panel of about 30 tests drawn from more than 3,000, and published member results. Membership from $399 a month per person.
Book a 20-minute callSee member resultsThis article is for educational purposes only and does not constitute medical advice. Consult a qualified physician before starting, stopping or modifying any medication. Individual results vary, and GLP-1 therapy should be tailored to your specific medical history.
Dr. Alec Weir is the Chief Medical Officer at Rebel Health Alliance (https://rebelhealthalliance.io), a 100% virtual, physician-led longevity practice in all 50 states. Learn more about how the program works or read the FAQ.