Medical disclaimer: This post covers the evidence on GLP-1 medications. It is not medical advice. Decisions about GLP-1 medication belong with your GP.
The Bottom Line: Most men who stop GLP-1 injections regain the majority of lost weight within a year. The medication suppresses appetite – it doesn’t fix the diet, habits, or hormonal environment driving the weight gain. The men who keep the weight off do specific things while they are still on the medication. Use the window while it’s open.
Most people who stop GLP-1 injections regain a lot of the weight within a year. In the STEP 1 trial extension, participants regained roughly two-thirds of what they had lost after stopping semaglutide (sold as Wegovy for weight management).
That is the part most men are not thinking about.
Not because these drugs don’t work. They do. But what a drug does and what it fixes are two very different things. I’ve spent 14 years coaching men over 40 through body transformation. I’ve watched enough quick fixes turn into expensive detours to know the difference.
Here’s what you need to understand.
How Do GLP-1 Medications Work for Weight Loss?
GLP-1 receptor agonists mimic a gut hormone your body produces naturally after eating. They slow gastric emptying, increase insulin release, and suppress appetite at the brain level. The result: you feel full faster, eat less, and your caloric intake drops by around 40% without feeling like you’re starving.
The two main drugs are semaglutide and tirzepatide. Semaglutide is available as Wegovy for weight management and as Ozempic for type 2 diabetes – they are the same molecule at different doses and with different approved uses. Tirzepatide is available as Mounjaro. The trial results are real. Participants on semaglutide lost around 15% of body weight over 68 weeks. Those on tirzepatide at the highest dose lost closer to 21%. Add structured lifestyle changes and results improve further.
In Australia, semaglutide as Wegovy and tirzepatide as Mounjaro are registered for weight management. Neither is broadly subsidised on the PBS for weight loss alone. Wegovy has been recommended for PBS subsidy only for a narrower group of people with obesity and established cardiovascular disease, subject to listing conditions and access criteria. For most men using these drugs for weight loss, this remains an out-of-pocket decision.
So yes. They work. That is not the issue. The issue is what happens when the injection stops and your old life is still sitting there waiting for you.
What Happens When You Stop Taking GLP-1 Medications?
When people stop taking these medications, most of the weight comes back.
The STEP 1 trial extension – the largest semaglutide follow-up study – found that participants regained roughly two-thirds of their prior weight loss within 52 weeks of stopping the drug. Not slowly. Fast. A post-hoc analysis of the SURMOUNT-4 trial on tirzepatide found that 82.5% of people who stopped had regained at least 25% of their lost weight within a year. Nearly a quarter had regained more than 75%.
The drug suppressed the symptoms. It didn’t fix the system.
This isn’t a criticism of the medication. It’s just what the evidence says. Obesity behaves like a chronic metabolic condition. Stop the treatment without building something in its place and you get a predictable result. You also get a lighter wallet and a heavier body – which is a worse position than the one you started from, because now you’ve lost time and money and you’re back where you were.
Do GLP-1 Drugs Cause Muscle Loss – and Why Does That Matter More After 40?
Here’s what matters most for you (it’s not the number on the scale.)
If you’re carrying significant visceral fat, your testosterone is probably lower than it should be. Visceral fat contains an enzyme called aromatase that converts testosterone into estrogen. More visceral fat means more conversion, which means suppressed testosterone. GLP-1 medications can reduce visceral fat, and reducing visceral fat can improve the hormonal environment in men – which may support improved testosterone levels in some. That’s a genuine benefit.
But only if the fat doesn’t come back. And without the right foundations in place, it usually does.
There’s a second problem: muscle loss.
Rapid weight loss – drug-assisted or not – costs you lean tissue. Across multiple clinical trials, lean mass accounts for roughly 20-40% of total weight lost on GLP-1 medications. Clinical body composition data consistently shows men lose proportionally more lean mass during weight loss than women. From your 40s onward, you’re already losing muscle naturally. You don’t have the buffer you had at 30.
Losing muscle accelerates your metabolic rate decline, makes future weight regain faster and harder to reverse, and affects your strength, your energy, and your functional capacity for the next 20 years.
Losing fat and muscle, then regaining fat, is not a result. It is a bad trade.
What Don’t GLP-1 Medications Fix?
GLP-1 medications suppress appetite. They don’t teach your body to eat differently. They don’t build the habits, knowledge, or behaviours required to maintain weight when the appetite suppression is removed. They don’t address the carbohydrate dependency, the stress-eating patterns, the poor sleep, or the sedentary default that drove the weight gain in the first place.
These medications work on the output side. They reduce how much you eat. The input side – why you eat what you eat, what your body does with it, how you live – stays exactly as it was.
That’s not a flaw in the drug. It’s just what a drug can and can’t do.
The men who get lasting results from GLP-1 therapy are the ones who use the reduced appetite as a window to rebuild how they eat and how they live. Most don’t. The weight regain data tells us that clearly.
The window is now. While appetite is suppressed, change the food, build the muscle, fix the sleep, and put structure around the day. Wait until hunger returns and you have made the job harder than it needed to be.
If you’re on one of these medications now, this is the window. Use it properly.
Tell me where you’re at.
What Do You Need to Do While Taking GLP-1 Medications?
The fundamentals don’t change. If you’re on a GLP-1 and ignoring these, you’re renting results, not owning them.
Nutrition quality is non-negotiable. When your appetite drops by 40%, every meal has to count. A 2026 narrative review covering six studies and 480,825 adults found nutritional deficiencies were common among GLP-1 users – vitamin D, iron, calcium, and protein intake were among the recurring concerns, with vitamin D deficiency reported in 13.6% of users at 12 months. Eating less means eating better. Not less of the same processed food.
A high-protein, lower-carbohydrate approach protects muscle and manages insulin better than anything else I’ve seen work long-term. The evidence on LCHF is not a trend. It’s physiology.
Protein goes up, not down. To protect lean mass during rapid weight loss, aim for 1.2 to 1.6 grams of protein per kilogram of body weight daily. Make protein the first priority at every meal, especially breakfast.
Resistance training is not optional. Two to three sessions per week. Compound movements – squats, deadlifts, rows, presses. Not for vanity. This is the mechanism that protects your metabolic rate and physical capacity when you’re losing weight fast.
Sleep and stress are not secondary issues. Poor sleep and chronic stress drive hunger hormones, cortisol, and insulin resistance directly. You cannot drug your way out of a bad stress response. These need attention – not eventually, now.
Are GLP-1 Medications Worth It for Men Over 40?
GLP-1s are a tool. A useful one, for the right man, in the right situation, under proper medical supervision.
They create conditions that make the work easier – reduced hunger, faster early weight loss, improved insulin sensitivity, potential improvement in testosterone. I’ve seen that window be genuinely valuable.
But the window closes. And I’ve seen what happens when men reach the end of it without anything built underneath.
The medication is not the enemy. Passive dependence on the medication is the problem.
In 15 years and 895+ clients, I’ve seen a consistent pattern: the men who keep the weight off are the ones who accept that the body they want requires the daily behaviours that produce it. Not for 68 weeks, while they take medication. Permanently. The medication can be part of that process. It cannot replace it.
I work with men on GLP-1 medications – and men who’ve come off them and watched the weight come back. The work is the same either way: fix the nutrition, protect the muscle, build the habits that hold when the drug doesn’t.
If that’s you and you want help, book a free call here and let me know. Tell me where you’re at.
Frequently Asked Questions
Will I regain weight after stopping Ozempic or Mounjaro?
Most people do. The STEP 1 trial extension found that participants regained roughly two-thirds of their weight loss within 52 weeks of stopping semaglutide. For tirzepatide, 82.5% of people who stopped had regained at least 25% of their lost weight within a year. The medication suppresses appetite – when it’s removed, appetite returns, and without rebuilt habits and nutrition foundations, so does the weight. Building those foundations while the medication is still working is the entire point.
Do GLP-1 medications cause muscle loss?
Yes, and this is a significant concern for men over 40. Clinical data shows lean mass can account for roughly 20-40% of total weight lost on these medications. Protecting muscle requires adequate protein intake (1.2 to 1.6g per kilogram of body weight daily) and structured resistance training two to three times per week while on the medication.
Can GLP-1 medications increase testosterone in men?
Potentially, as an indirect effect. Visceral fat contains an enzyme called aromatase that converts testosterone into estrogen. GLP-1 medications can reduce visceral fat, which may improve testosterone levels in some men. This benefit only holds if the visceral fat doesn’t return after stopping the medication.
How much do GLP-1 medications cost in Australia?
Semaglutide as Wegovy and tirzepatide as Mounjaro are not broadly subsidised on the PBS for weight loss alone. You’re looking at $350 to $645 per month out of pocket depending on the medication and dose. At that investment, the question worth asking is what you’re doing to make sure the results stick when you stop.
What should I eat while taking GLP-1 medications?
Prioritise protein above everything else – at minimum 1.2 to 1.6 grams per kilogram of body weight per day. A high-protein, lower-carbohydrate approach protects lean mass and manages insulin more effectively than a standard diet. Eating less is not enough – eating less of the wrong food while deficient in protein and micronutrients produces worse body composition outcomes.
Do I need a coach while on GLP-1 medications?
You don’t need one. But the data is clear on what happens to most people without structured support: the weight comes back. A coach’s job isn’t to manage the medication – that’s your GP’s role. It’s to fix the nutrition, training, sleep, and stress foundations that determine whether you keep the results when the medication stops.
If you’re spending $400 a month on a drug and not addressing those foundations, you’re renting results. Start the conversation here, to make sure you’re not throwing away your money.
Resources
- Regeneron COURAGE Trial interim results. Approximately 35% of semaglutide-induced weight loss was due to loss of lean mass.
- American Diabetes Association: New GLP-1 Therapies Enhance Quality of Weight Loss by Improving Muscle Preservation. 2025.
- Wilding JPH et al. Weight regain and cardiometabolic effects after withdrawal of semaglutide: The STEP 1 trial extension. Diabetes, Obesity and Metabolism. 2022;24(8):1553-1564.
- Aronne LJ et al. Cardiometabolic Parameter Change by Weight Regain on Tirzepatide Withdrawal: A Post Hoc Analysis of the SURMOUNT-4 Trial. JAMA Internal Medicine. 2025.
- Urbina et al. Micronutrient and Nutritional Deficiencies Associated With GLP-1 Receptor Agonist Therapy: A Narrative Review. Clinical Obesity. 2026.
- Harvard Health Publishing: Study: Taking GLP-1 drugs may increase risk of key nutrient deficiencies. March 2026.
