By Chris Cristini | Owner, Cristini Athletics | R.Kin, CSEP-CEP, CF-L2
GLP-1 medications are everywhere right now. Ozempic, Wegovy, Mounjaro – you’ve heard the names, you’ve probably seen the results, and if you’re reading this, there’s a good chance you’re either on one, thinking about one, or know someone who is.
I want to be direct with you, because that’s what I’ve always done with the people I work with. Whether GLP-1 medications are right for you is not my call. That decision belongs to you and your prescribing physician. What I am qualified to talk about – after 20 plus years in this industry as a Registered Kinesiologist, a Certified Exercise Physiologist, and a CrossFit coach – is what has to happen on the fitness and health side of the equation if you actually want these medications to work for you long-term.
And that’s where most of the conversation stops too early.
What GLP-1 Medications Actually Do
Before we get into the fitness piece, a quick primer on the science – because understanding the mechanism helps you understand why what I’m about to say matters.
GLP-1 (glucagon-like peptide-1) is a hormone naturally produced in your gut after you eat. It signals satiety, slows digestion, and stimulates insulin production. GLP-1 receptor agonist medications like semaglutide (sold as Ozempic and Wegovy) essentially mimic this hormone at a much more potent level – the result is a significant, sustained reduction in appetite and caloric intake.
On average, people on semaglutide lose around 10–15% of their body weight. Mounjaro (tirzepatide) goes a step further – it’s a dual GLP-1 and GIP receptor agonist, and clinical trials have shown weight loss outcomes of 22% or more, outperforming Ozempic in head-to-head studies. These are meaningful, real results that are genuinely changing lives.
But here’s what the Instagram posts and the news headlines leave out.
The Harsh Reality: GLP-1s Alone Are Not Enough
Eating less is not the same as eating well. And losing weight is not the same as getting healthy.
I see this played out constantly. Someone dramatically reduces their caloric intake – which these medications are very effective at achieving – but what they’re eating is still largely fast food, processed snacks, and nutritionally empty meals. Just less of it. The scale moves. But their energy is poor, their recovery is terrible, and their body composition isn’t improving the way they hoped.
Being lighter is not the same as being well. Skinny and healthy are not synonyms.
The other thing that doesn’t get talked about enough: every pound you lose includes muscle mass loss. This is a consistent clinical finding across the research. When you’re in a significant caloric deficit – which is exactly what GLP-1 medications create – your body doesn’t just burn fat. It catabolizes muscle tissue too, and the rate of lean mass loss can be disproportionate to the fat loss.
That has real, lasting consequences for your metabolism, your physical function, your bone density, your strength, and your long-term health. A 2023 study published in The Lancet confirmed something else that matters enormously: the majority of people who stop GLP-1 medications without lifestyle changes regain most of the weight they lost. The medication suppresses appetite. It does not rewire your habits, your relationship with food, or your body’s capacity to maintain weight on its own.
So what does that tell you? It tells you that the medication is a tool. And like any tool, it only works well when it’s part of a bigger plan.
What You Actually Need: A Real Team
This is where I’ll give you my honest take as a fitness professional. If you’re on a GLP-1 medication – or seriously considering one – you should be working with three types of professionals simultaneously:
- A fitness professional (a qualified trainer or coach)
- A nutritionist or nutrition coach
- A therapist or psychologist
Let me explain why each one matters.
Why a Fitness Professional Is Non-Negotiable
The role of a fitness professional here isn’t just to give you something to do while you lose weight. It’s far more specific than that.
You need someone who understands how to calibrate training to a reduced caloric intake. Programming that was appropriate for you before starting a GLP-1 medication may be too aggressive now – because your fuel availability has changed significantly. Training too hard on too little fuel doesn’t produce better results. It produces fatigue, injury risk, and burnout.
You also need structured resistance training – and you need it prioritized. The research is clear: structured resistance training is the primary protective factor against the disproportionate muscle loss that accompanies GLP-1-driven weight loss. This isn’t about aesthetics. It’s about preserving the metabolically active tissue that determines your long-term health outcomes.
Beyond the programming, there’s a relationship piece that matters more than most fitness professionals will admit. Many people who are now succeeding on GLP-1 medications spent years feeling self-conscious in gym environments, feeling like training wasn’t for them, or associating exercise with embarrassment and failure. As the weight comes off and the body changes, we have a genuine opportunity to build a positive, sustainable relationship with training – one that feels good and motivating, not punishing. Done right, this is one of the most powerful things a coach can give someone.
And critically – your fitness plan needs to be designed to sustain you both on and off the medication. Because at some point, most people come off it. What happens then is a fitness question, not a medical one.
Why Nutrition Education Is Different From Eating Less
The GLP-1 medication handles the appetite suppression piece. But it does nothing to teach you what to eat, how to fuel your body, when to prioritize protein, how to structure your meals to support training, or how to maintain healthy eating patterns long after the medication is a memory.
A nutrition coach or registered dietitian fills that gap. They help you build the knowledge and the habits that sustain results. Eating 1,400 calories a day of nutrient-dense, well-structured food produces a fundamentally different outcome than eating 1,400 calories of fast food – even if the scale says the same thing in the short term.
Macro-based nutrition education, specifically, gives people the framework to understand not just how much they’re eating but what they’re eating and why it matters for their goals. That knowledge is the foundation that holds everything else up when the medication is no longer in the picture.
The Mental Health Piece – The One People Skip
This is the part of the conversation that gets left out most often, and I think it’s the most important.
Rapid body transformation is a profound experience – and not always in the ways people expect. When your physical appearance changes significantly and quickly, your sense of identity can shift in ways that feel disorienting. Patterns and emotions that you may not have fully recognized before – your relationship with food, with comfort eating, with social situations that involve eating, with how you see yourself – can surface in new ways.
This is not weakness. This is human. And it needs support.
I’ve seen people go through exactly this journey, make real physical progress, and then hit a wall – not a physical one, but a psychological one – and step back from everything they’d built. When that happens, the instinct is often to quit the gym, to stop training, to retreat. But quitting the gym during a struggle doesn’t mean you need less coaching. It means you need more specific coaching – you need someone who understands the psychological dimension of this kind of transformation.
A therapist or psychologist who works in this space can help you process the identity shifts, address the emotional patterns that have always been there, and build the mental resilience that makes long-term success possible. If the physical and mental health pieces aren’t being supported simultaneously and consistently, the chances of reverting to old habits are high. That’s not my opinion – that’s what the data shows.
The Bottom Line
GLP-1 medications can be a powerful catalyst. They’re not magic, and they’re not a shortcut – but used well, they can create the space and the momentum for real, lasting change. What fills that space is what determines whether you actually get there.
You need a fitness professional who understands how to program for you in this context – protecting your muscle, calibrating your training, and building a relationship with movement that will last.
You need a nutrition coach who can turn “eating less” into “eating well” – so you’re building health, not just losing weight.
And you need mental health support – because the psychological journey of rapid body transformation is real, it’s significant, and it deserves just as much attention as the physical one.
If you’re doing all three at once? Your chances of long-term success go up dramatically.
If you’re doing none of them? The research is pretty clear on where that leads.
Taking the Next Step
If you’re on a GLP-1 medication and you want to do this right, I want to introduce you to something we’ve designed specifically with you in mind.
STRONG START is an 8-week beginner strength program at Cristini Athletics Markham (9833 Markham Rd) built specifically for adults currently on GLP-1 medications. It’s led by Coach Maryam Marashi (PhD, Exercise and Health Psychology) in partnership with Physiotherapist Farnaz Suleman – which means you’re getting the fitness and the clinical support in the same program.
This program addresses exactly what I’ve outlined in this post: training that’s calibrated to where you are right now, muscle preservation as a primary goal, and a psychologically informed coaching approach that builds a lasting relationship with movement.
Starts July 9th. Limited to 6 participants. May be covered under physiotherapy benefits.
To learn more, DM us the word STRONG START on Instagram, or visit the Get Started page on our website. Space is genuinely limited – this isn’t a marketing line. Six people, one coach, one physiotherapist, eight weeks of purposeful work.
For more articles like this, visit our blog at cristiniathletics.com.
Frequently Asked Questions
Should I start exercising before or after I begin a GLP-1 medication?
Starting movement before you begin a GLP-1 medication is ideal – it gives your body a baseline of activity and helps establish habits before your appetite and energy patterns change. That said, it’s never too late to start. If you’re already on the medication, begin working with a qualified fitness professional now rather than waiting for a “better time.” The most important variable is working with someone who understands how to program appropriately for where you are.
Will I lose muscle on Ozempic or Mounjaro, and what can I do about it?
Yes – muscle loss is a consistent clinical finding with GLP-1 medications, particularly during periods of rapid weight loss. This is because your body draws on both fat and lean mass for energy when in a caloric deficit. The primary protective strategy is structured resistance training – specifically, progressive strength training that maintains mechanical demand on your muscles while you lose weight. A fitness professional who understands this context can build a program that minimizes lean mass loss and preserves the muscle you’ve earned.
What should I eat while on a GLP-1 medication?
Because GLP-1 medications significantly reduce your appetite and caloric intake, the quality of what you do eat becomes even more important. Prioritizing protein intake is critical – it’s the macronutrient most directly linked to muscle preservation. Beyond that, working with a nutrition coach to build a macro-aware eating plan ensures that reduced calories still deliver adequate nutrients, energy, and support for training. “Eating less” is not the same as “eating well,” and both matter for your long-term health.
What happens when I stop taking a GLP-1 medication?
Research – including a widely cited Lancet study – shows that most people regain the majority of weight lost after stopping GLP-1 medications if lifestyle changes haven’t been established. The medication suppresses appetite; it doesn’t permanently change your habits or metabolism. This is why building structured fitness habits, nutritional knowledge, and mental health support during your time on the medication is so important. The goal is to use the medication’s window to establish sustainable behaviors that continue independently of it.
I’ve always hated the gym and never felt comfortable exercising. Can a GLP-1 medication help change that?
The medication can change your body – but building a positive relationship with exercise is a coaching outcome, not a pharmaceutical one. What GLP-1 medications can do is create physical changes that reduce some of the barriers people feel in gym environments. What a skilled fitness professional can do is meet you where you are, design training that feels achievable and good, and progressively build your confidence and capacity over time. Many people who previously felt unwelcome or out of place in fitness settings find that this period of change – when supported well – becomes the foundation of a genuine, lifelong relationship with movement.
Chris Cristini is the owner of Cristini Athletics, a CrossFit gym with locations in Markham and Vaughan, Ontario. He holds a Bachelor of Kinesiology, a CSEP Clinical Exercise Physiologist designation, and a CrossFit Level 2 certification, with 16+ years of coaching and programming experience. Cristini Athletics also operates Cristini Athletics Therapy, an integrated sports physiotherapy clinic.