WHAT HAPPENS TO YOUR BODY ON GLP 1'S — AND HOW DO YOU PROTECT YOUR MUSCLE?

GLP-1 medications are changing the landscape of weight loss. Appetite is reduced, weight comes down, and for many, the process can feel surprisingly effortless.

But as Derek Adu-Sarkodie — a doctor and certified personal trainer — is seeing in both clinic and coaching settings, the reality is more nuanced. While these medications can be highly effective, they can also lead to unintended muscle loss if strength training isn’t part of the picture.

“GLP-1 medications can work well for weight loss, but if strength training isn’t built in, people can lose muscle as well as fat," Derek tells us. "From working with patients in the clinic and clients in the gym, preserving muscle is non-negotiable for long-term health."

That balance is exactly where the focus needs to shift. Read our full interview with Dr. Derek below.

From your perspective, what are the biggest physiological changes you're seeing in patients using GLP-1 medications?

The most noticeable thing I see in my practice as a doctor is how effectively these medications suppress appetite and reduce overall food intake in some cases. But the flip side is that many people end up eating far less protein and fewer calories than they realise, sometimes for months on end. When that happens, you start to see muscle loss alongside the fat loss which is what we're trying to avoid.

It's worth noting that we're still in relatively early days with these medications for weight management. We don't yet have robust long term studies on body composition changes over years or on what happens when people stop taking them. What we're seeing clinically is prompting us to be proactive about muscle preservation, but the evidence base is still developing.

How does muscle mass typically respond during GLP-1-supported weight loss?

If someone isn't deliberately doing strength training, losing some muscle alongside the fat is pretty common. This happens especially when the weight comes off quickly. That's a concern because muscle isn't only about looks. It's metabolically active tissue that helps with insulin sensitivity and keeps you strong. From a longevity perspective, holding onto muscle during weight loss is absolutely critical as it keeps you independent as you get older. 

Where do you see strength training fitting into the protocol for GLP-1 patients?

Strength training is essential. When done correctly, it gives your body the signal it needs to hold onto the muscle whilst you lose the weight. I’d say even a modest, well planned routine done consistently can make a real difference to outcomes.

What mistakes or misconceptions do people have about exercise while on GLP-1 drugs?

The biggest misconception is that the injection alone will do all the work. That you'll just take it, the weight will drop off, and that's that. But without building some sort of sustainable lifestyle habits around it, particularly around strength training or focussing on your nutrition, people often regain the weight when they stop or reduce the medication.

One of the biggest risks we hear about is loss of lean mass. For people who struggle to get into a gym or build consistent habits, what role can accessible home strength training play?

Working out at home can be a game changer, honestly. When you remove the barriers such as commuting to a gym, feeling self conscious or needing lots of kit, people are far more likely to actually do it. I am a big believer in the saying that consistency beats perfection. Doing  something consistently at home beats sporadically turning up to a gym. For long-term adherence, making it easy and accessible is half the battle.

From a training standpoint, what kinds of foundational strength movements are most important for preserving muscle during weight loss?

As a certified personal trainer working with my clients, I always focus on compound movements. These are exercises that use multiple muscle groups at once. Examples are things like squats, hinges, presses and pulls. These movements support muscle retention, bone density and the kind of strength you use in everyday life.

But when I put my doctor hat on, I see the long-term consequences of neglecting this kind of training. In my GP practice,  I'm treating patients with hip fractures, osteoporosis, and loss of independence. These are conditions that are often preventable with consistent strength work earlier in life. Building that functional strength and bone density now, particularly during weight loss, can genuinely be the difference between staying active and independent in your 70s and 80s, or facing a significantly reduced quality of life.

If someone has limited time, what's the minimum amount of strength training you'd recommend?

Two to three short sessions a week is usually enough to maintain muscle if it's programmed properly. The aim is to preserve strength, function and metabolic health whilst the weight's coming off. That's entirely achievable without living in the gym.

What are some techniques your clients have successfully used to integrate strength training into their lives?

The ones who stick with it tend to keep things simple. Short sessions, realistic goals, and training in a way where it suits them. The key is building it into your routine so it just becomes part of what you do rather than something that depends on motivation. Once it's a habit, it's so much easier to maintain.

About Fittle

Fittle creates beautifully designed, space-conscious strength training systems that integrate into real homes. Every Fittle Box includes two sets of dumbbells — built for shared training, long-term use, and consistency without compromise.