The new class of weight loss drugs such as Ozempic is one of those topics I’ve been well aware of for quite a few years because it’s hard to miss these days in mainstream and social media.
I’ve watched a number of scientific presentations and read quite a lot, though I haven’t gone that deep into the entire body of research yet. Talking about drugs of any kind is usually not something I focus on. It’s also out of my scope of practice to advise anyone whether to take them or not, only share what factual data I’ve come across so far for informational purposes only. Consult a good doctor for medical advice.
These are my initial thoughts and opinions from a fitness professional’s perspective that I’m offering because readers keep asking me…
Also please note, this is not a criticism of anyone using the drugs under medical advice. Anyone who has worked with their doctor to use medication and has achieved healthy weight loss, especially maintained it, and especially done it in conjunction with fitness-oriented lifestyle changes has my congratulations.
Ozempic is one of the brand names for semaglutide. Another one is Wegovy. Similar products include tirzepatide (trade name Mounjaro), and there are others. These drugs are known as a GLP-1 agonists. GLP-1 is glucagon like peptide, a hormone secreted in your gastrointestinal tract that makes you feel fuller. (Remember, there are hormones that make you feel hungrier, but there also hormones that make you feel fuller).
The effects also occur in the brain as there are areas of the brain that can also send signals to make you feel fuller. It’s a single weekly injection and that’s the case because unlike the GLP-1 hormone itself, the semaglutide drug was developed to have a much longer half life.
So this weight loss drug works by making you eat less. You simply are not hungry and you feel fuller after eating. It is not a thermogenic or metabolism booster which would work on the burning more side. Ozempic works on the eat less side. That’s probably why it’s been proven so effective because doing things that make you feel full or simply not feel like eating is the more effective side of the equation. We’ve also seen thermogenics that have more frequent and potentially more harmful side effects.
But all drugs have potential side effects. For Ozempic / semaglutide, the most common is nausea. I saw stats comparing two studies, and in adolescents 65% reported nausea while in adults 33% reported nausea. Other side effects, also fairly common (often 20%-35% of users) included abdominal pain, vomiting, diarrhea, and dizziness.
As for more severe side effects, there have been reports of stomach paralysis or intestinal blockage, which is likely associated with the fact that Ozempic slows gastric emptying so much. You see case studies pop up in the news every so often, but it appears rare.
In the case for Tirzepatide, this is the list of warnings and side effects taken straight from the Eli Lilly website:
Tumors in the thyroid, including thyroid cancer, inflammation of the pancreas (pancreatitis), low blood sugar (hypoglycemia), serious allergic reactions, kidney problems (kidney failure), severe stomach problems, changes in vision, gallbladder problems.
Whether there are long term side effects with prolonged use or a long time after discontinuing, I’m not sure. There have been some scare stories about cancer, (thyroid in particular) but I believe most or all were based on rodent studies. And running counter to this particularly scary side effect are reports that this class of drugs might reduce risk of obesity-related cancers due to the health benefits of the weight loss.
One side effect that has been alarming to many people in the fitness industry is large losses of lean body mass.
In one study most of the weight (60%) came from lean mass and it was commonly over 40%. Im not sure if there is another mechanism, but a simple explanation is that people simply may not be eating enough because they’re no longer hungry. That could include not eating enough protein because we know that protein is the most filling / satiating macro.
It’s a real concern, but possibly not as bad as it sounds because the subjects may not have been lifting. I have read countless studies testing a variety of diets (no medications used) where a lot of lean mass was lost simply because the subjects weren’t training. This would suggest that it’s vital for people on this class of weight loss drugs to lift or do some kind of resistance training.
And remember, aside from muscle loss causing strength loss and a body that may look “skinny fat” (lacking in athletic muscle), we know from other research that losing lean mass is associated with regaining the weight when the intervention ends.
Even though there are potential side effects, the reason it has become so popular is because the drug works and works well. 20 to 30 pounds of weight loss or 15% of body weight is not uncommon, sometimes less, sometimes even more.
What happens when you stop taking it? Can you stop taking it? The latter question is one for a doctor. The drug was originally created as a glycemic control treatment for diabetes. As a medical issue this has to be a conversation with a medical professional as whether to take it and for how long. Same thing with questions about A1C or other specific health markers, but improving glycemic control is one of the main benefits touted from the drug makers.
Strictly from a weight loss perspective, everyone can probably guess what happens when you stop taking it. People regain the weight at about the same rate and percentage as most people when going off any diet or weight loss intervention. Only long term lifestyle change – better nutrition, continuation of weight training and high activity etc, with good adherence and consistency, can assure weight loss maintenance.
So, despite how attractive it appears to take a drug that’s been proven highly effective, without committing to lifestyle change it’s not unfair to say it’s just another quick fix or crutch like any other short term intervention. We saw the same thing with the old generation of prescription appetite suppressants – they only worked as long as you continued taking them. (And they too had side effects, and some were pulled off the market eventually for safety reasons).
Weight loss drugs might make sense for certain individuals just like bariatric surgery might make sense in some cases. Semaglutide has remained somewhat controversial however for more than one reason. It’s expensive for one. I think it’s around a thousand a month. Which also brings up the controversy of whether it’s being overprescribed because some people may be making a lot of money off it and eager to continue promoting and selling it. Novo Nordisk is now one of the most valuable companies in the world. So is Eli Lilly, maker of Mounjaro.
It also seems a lot of people take it who are not diabetic, are using these drugs just for weight loss, and might not have that much fat to lose. This has also created some controversy and discussion/ debate because when someone has glycemic regulation issues and is so overweight that it’s a health risk, then it seems an appropriate prescription if someone chooses to go down that path and their doctor agrees. But someone who is reasonably healthy and is looking to drop a small amount of “vanity pounds” it doesn’t seem as appropriate and it’s certainly not necessary.
Adding to the controversy on this matter it appears that some bodybuilders and physique athletes (who are not diabetic, obese, or unhealthy) are using GLP1 agonists like semaglutide purely for fat loss (to control the hunger of a contest diet). Some have publicly said so in their social media. Drugs in physique sports is a whole other can of worms, so I won’t open that one further and we’ll just end on that point for now.
If I look deeper into the existing research on this class of drugs, or if if any important news or new findings are publicized, I may circle back and add an update. Readers who want to share opinions or experiences, positive or negative are welcome to post in the comments below.
-Tom Venuto,
Author of Burn the Fat Feed the Muscle
Founder of Burn the Fat Inner Circle
About Tom Venuto, The No-BS Fat Loss Coach
Tom Venuto is a natural bodybuilding and fat loss expert. He is also a recipe creator specializing in fat-burning, muscle-building cooking. Tom is a former competitive bodybuilder and today works as a full-time fitness coach, writer, blogger, and author. In his spare time, he is an avid outdoor enthusiast and backpacker. His book, Burn The Fat, Feed The Muscle is an international bestseller, first as an ebook and now as a hardcover and audiobook. The Body Fat Solution, Tom’s book about emotional eating and long-term weight maintenance, was an Oprah Magazine and Men’s Fitness Magazine pick. Tom is also the founder of Burn The Fat Inner Circle – a fitness support community with over 52,000 members worldwide since 2006. Click here for membership details
Folks taking these drugs are not hungry because these drugs work on appetite by slowing stomach emptying. The slower your stomach empties, the longer you are not hungry. The delayed stomach emptying is why you can see stomach paralysis, nausea, vomiting and abdominal pain. As a pharmacist, I am not a fan of use for weight loss.
Yes I understand it was originally intended for treatment of type2 diabetes… thus the use for weight loss is quite controversial indeed
The risks of thyroid cancer are greatly increased with these drugs. There is also an over 200% increase in deep vein thrombosis with these drugs.
I judge the character of a corporation from how they advertise on television. Do they use classical conditioning of Ivan Pavlov and B. F. Skinner to associate the image of the drug with syrupy sentimental sounding music and images of families on vacation? This demonstrates their disrespect for their target audience. Do they go out of their way to insult the intelligence of their target audience by going out of their way to look and sound stupid, for instance people grunting, “Oh! Oh!, Oh!,” thereupon demonstrating contempt? If they do, there will be something wrong or even unsafe about the drug.
Sounds like a good criteria for judgement of character. Thank you for posting.
I didn’t know about the lean muscle mass stat, but makes sense knowing the mechanism of action and when you consider most folks on it likely aren’t engaged in a consistent resistance training routine. Would be interesting to see what happens if someone rightly on this drug for obesity let’s say, actively lifted 2-3xs/wk while ensuring they get enough protein daily. I would suspect some lean body mass loss due to the overall weight loss, but perportionally I wonder if it would be significantly less? Sounds like getting the nutrients right is even more vital when on this class of drugs for a healthier outcome…and yes, how many after investing so much money in this will actually end up with sustainable results? Thanks for the article!
Yes good questions. The two most important keys to maintaining lean body mass while in a calorie deficit (with or without medication) are: 1. consistent progressive resistance training and 2. Sufficient protein. Regarding #2, if calories are extremely low, it becomes more difficult to eat enough protein. Also if someone’s appetite is dramatically suppressed, when they DO actually feel like eating, are they more likely to go for the tuna fish, chicken breast, egg whites, etc, or the carbs and fat?