The Truth About GLP-1 Weight Loss Drugs

If you're reading this, there's a good chance you're on Ozempic, Wegovy, Mounjaro, Tirzepatide or some other made-in-a-kitchen-sink non approved GLP-1 receptor agonist drug - or maybe thinking about getting started. The weight is coming off. The scale is moving. You feel like you've finally cracked the code.

I'm going to tell you something you may not want to hear: the scale is lying to you. And if you're using these drugs hoping to improve your body composition, you could be setting yourself up for a disaster that might not show up for six to twelve months. I’m going to skip the bits about the side effects like possible nausea etc. Only because you would have probably already read up on that bit somewhere else when you considered these drugs. 

Before you think I am going to slam or discredit the drugs, or maybe try to convince you that you are wasting your money - I am not. None of what I’ve written is “medical advice” either. 

This is not a social media post either - where your extended attention scores me points on some algorithm. It’s the PIT Singapore’s own blog and this post is just a bit of a read for some. But I assure you that the information is important for those of you using, or considering GLP-1s. 

So please read to the end. 

What GLP-1s were actually designed for.

GLP-1 receptor agonists were not invented to make you skinny. They were initially designed to treat type 2 diabetes. The first one, Tirzepatide, was launched in the early 2000s to help diabetics control blood sugar. GLP-1 is a hormone your gut naturally releases after a meal -  it tells your pancreas to release insulin, slows down how quickly food leaves your stomach, and signals to your brain that you're full.

These synthetic versions hang around in your body far longer than the natural hormone. For diabetics, that meant better blood sugar control. The “side effect” (and this is critical) was significant appetite suppression and hence - weight loss. 

Pharmaceutical companies noticed - CHA-CHIIING! $$$$$$$ 

They ran trials specifically for weight loss. Semaglutide and tirzepatide are now medically approved for obesity, but the mechanism is the same: shut down hunger, slow digestion, and you eat far less without trying.

This is the point I want you to sit with. The drug works by helping you eat less. It doesn't burn fat. It doesn't preserve muscle. It doesn't build a body. It just drastically turns the volume down on hunger. 

What happens with all that “eating less” depends entirely on what you do (or don't do) with your nutrition and training.

Weight loss is not fat-loss

When the scale drops, you assume that number represents fat. It doesn't. Weight loss is a mix of fat, muscle, water, glycogen, and gut contents. Yup you can drop a couple of grams just by dropping a deuce.

Under good, and preferable conditions - adequate protein, resistance training, a moderate rate of weight loss - most of that weight drop comes from fat. 

Under poor conditions - low protein intake, no training, aggressive caloric deficit - a substantial portion comes from muscle.

Withoutsome form of intervention, 25 to 40 percent of the weight you lose on a GLP-1 drug will come from lean mass.Read that again. If you lose 20kg, somewhere between 5 and 8 of those kilograms may not be fat at all. Some of that is muscle.

That's not fat loss. That's getting smaller.

Why losing muscle is a disaster

Muscle is your metabolic engine. Every kilo of muscle on your body burns calories around the clock - not a huge amount, but it adds up. Beyond that, muscle is metabolically active in ways that pure bodyweight isn't: Muscle improves insulin sensitivity, regulates blood sugar, supports bone density, and is the single biggest predictor of how well you'll function as you age.

When you lose muscle, three things happen.

Your metabolism drops. Your basal metabolic rate is largely determined by lean mass. Less muscle equals fewer calories burned at rest. The maintenance calorie level that allowed you to lose weight in the first place will keep dropping as you shed muscle - which means you need to continuously eat less and less to keep losing.

You set up rebound weight-gain. When you stop the drug - and most people do, because of cost, side effects, or life circumstances - appetite roars back. But now you have a lower metabolism and less muscle to soak up calories. Not only is the regain fast; it comes back almost entirely as fat. Your body composition ends up worse than where you started. 

If you think none of this applies to you because you are cocksure that you won’t stop -please re read the last part of previous paragraph on metabolism dropping and let it sink in a bit longer ok?

Lower weight on the scale doesn't necessarily mean you look better. People who lose significant muscle alongside fat often end up soft and undefined, with poor strength and a frame that looks older than it should. In other words, your fat to muscle ratio might still be high due to a loss of muscle. 

“But I still lose more fat than muscle right? So not so bad right?” 

Please re read last line of previous paragraph AGAIN on metabolism dropping and let it sink in a liiiittle bit longer.

This is the trap. The scale tells you you're winning. Your body composition (and health) is telling a different story.

*At this point, if you’re already started on GLP-1s and are going “Oh f#c%!”. 

Relax.. 

Keep reading lah.

The protein problem

Contrary to what many people think, the drug ITSELF does not cause muscle loss. Many trainers will hate to admit this - The drug actually DOES work. It does do its job of appetite suppression. And it does it well. 

But here's where the drug works against you. GLP-1s suppresses appetite so effectively that hitting adequate protein (Approx 1.2 – 1.6g per kilogram of bodyweight) becomes genuinely difficult. 

Many users report feeling full after a few bites. Smell aversions are common. Protein-rich foods - meat, eggs, fish, dairy - often feel heavy and unappetizing precisely when you need them most.

If protein intake drops, your body has no choice. It will break down muscle to supply amino acids for essential functions. The drug doesn't care that you wanted to lose fat - it just helps you eat less. If less food means less protein, muscle pays the price. 

This also means that someone on GLP-1s suffer the same problem as someone who goes on an aggressive diet that doesn’t consume enough protein. The drug is not exactly the main cause. 

If you’re on GLP-1s, or thinking of going on GLP-1’s, or if you simply have trouble consuming enough protein - Here's a protein protocol that I suggest:

Eat protein first at every meal. Before vegetables, before carbs, before anything else. You only have so much appetite because of the medication - spend it on the macronutrient that matters most. And nooo, I am not saying that your vegetables and carbs are not important. Don’t be one of those annoying people that nitpick and misquote other people to attempt to make themselves sound smarter. Please don’t be a CB ok?

Spread it out. Plan your protein consumption out throughout the day. For example, if you are a big guy and need to consume 180g of protein a day - It might be easier to consume 6 meals of 30g of protein, vs 3 meals of 60g. Again this is just a suggestion. Whatever protocol works for you. If the former protocol of 3 meals works better for you - go for it.

Prioritize high-leucine sources - whey, lean meats, eggs, Greek yogurt. Leucine is the amino acid that signals muscle protein synthesis. 

Whey protein is the whey to go. 

Even Jesus took it. 

Yah-whey. 

Geddit? Geddit?

Ok, sorry for the dad jokes. Back to the article. 

Let me show you the whey (Ok that was the last one. Promise)

Use protein shakes strategically. When solid food feels impossible, a protein shake can deliver 25 to 30 grams of protein in a shaker bottle. Don't be too proud to use them. And no, they do not destroy your liver, kidneys, make your private bits shrink or swell or whatever fear mongering influencers tell you. 

Resistance training is NOT optional.

Diet alone cannot save your muscle. Your body adapts to demand. If you don't ask it to be strong, it won't stay strong. Cutting calories without lifting weights is a clear signal to your body that muscle is expensive tissue you don't need.

Resistance training - two to three sessions per week, hitting major muscle groups, with real intensity — is the single most effective intervention to preserve lean mass during fat loss. It is not optional. It is not “nice to have.” It is the difference between losing 20kg and looking like a smaller, weaker version of yourself, and losing 20kgs and looking like a leaner, fitter, and healthier version of yourself.

You don't need to train to be a bodybuilder. You need three things:

Compound lifts - squats, hip hinges, rows, presses, pulldowns. Movements that recruit multiple muscle groups in one go.

Effort that matters - sets taken close to failure. “Easy“ work does not send the signal.

Progressive overload - adding weight, reps, or sets over time. The body adapts to stress, not to repetition. 

The bottom line.

The GLP-1 receptor agonist is a tool. Does it work? Yes, clearly so.

It is however, not the strategy. 

It was designed to help diabetics manage blood sugar, and the appetite suppression that comes with it is a very powerful lever for fat loss - but only if you build the rest of the system around it.

Use the drug to control intake. Use protein to preserve muscle. Use the iron to earn the body you actually want.

Anything less, and the scale is just lying to you.

Also……

if you did the 3 things mentioned (Caloric deficit, prioritise protein and resistance train) consistently enough, you’d be able to lose bodyfat as well. 

Without the drugs. 

But at a moderate pace.

So,

If you’re on GLP-1s - Consume adequate protein, train, total calories in is less than calories out. You’ll lose weight and preserve muscle. But you might also have to deal with side effects such as nausea, delayed stomach emptying (Gastroparesis), reflux etc etc. 

Of course there are also benefits like lower blood pressure, reduced cardiovascular risk, better……. Eh? 

Wait a minute. 

Aren’t these benefits also the same as when you lead a healthier lifestyle and have better body composition. Hmmm…..

Anyway.

If you’re on GLP-1s - Don’t eat enough protein, don’t train, total calories in is still somehow higher than calories out (Think overconsuming alcohol and fat – which is 7 and 9 calories a gram respectively) -  You’re going to be one of those guys that claims “GLP-1 drugs didn’t work for me.”

If you’re NOT on GLP-1s - Consume adequate protein, train, total calories in is less than calories out. You’ll also lose weight and preserve muscle. Ok, to be fair, there is actually a little more to this but it’s not the subject I am diving into here. But this is the gist of it.

PLUS - if you do the resistance training bit at the PIT Singapore, the only side effect: is a good time. 

If you’re trying to lose bodyfat, or want to improve your health and fitness, contact us to schedule a non-obligatory (and complimentary) consultation. 
*Always consult a doctor or health professional when considering any type of medication or drug.

Author : Henson Irving - PIT Director