The GLP Gotcha

GLP-1 drugs work, but there's a catch

The recent ascent of weight loss drugs such as Ozempic and Wegovy has been as close to a wonder drug for weight loss as there ever has been. It’s clear by now that for many people, these drugs are an effective, safe, and easy way to lose weight. Of course, there is no biological free lunch; any drug that goes into your body has the potential for unwanted side effects, and GLP 1 receptor agonist drugs are no different.

I want to be clear: this will not be a hit piece for those who choose this route. There are those in the fitness industry who have taken a hostile approach to people using GLPs, with the usual attacks on the overweight or obese. They’re lazy, just need to eat less and move more, and they lack the willpower to stop eating fast food and cook more at home. The fact that personal trainers and anyone else in the fitness industry would bash someone who is actively trying to improve their health and turn around and ask them to give them money so they can lose weight ‘the right way’ is beyond absurd.

I believe that these drugs can benefit trainers like me by creating a new population that needs the service we provide. The stigma of being overweight can prevent an obese person from ever stepping into a gym or attempting to exercise in the first place. Losing weight could give them the confidence to try something new, which, combined with their weight loss, could improve their health even more.

For most of my adult life, losing weight hasn’t been a goal of mine. I can’t say that I can completely empathize with those who have spent years struggling with myriad diet and exercise routines only to make little or no progress. However, I understand their desire to be healthy and robust via regular exercise and resistance training. Everyone should exercise, regardless of their weight.

The GLP Problem

A recent study by Heymsfield and Gonzalez et al. sheds light on what I believe to be the biggest issue with these drugs: They reduce the amount of FFM (fat-free mass, aka muscle) far greater than dieting alone. Their study found that the loss of FFM ranged from 25% to 39% of the total weight lost over a span of 36 to 72 weeks while using a GLP 1. This is much higher than the typical amount of FFM lost when dieting alone, which ranges from 10% to 30%. One must also remember that people using GLP’s are losing more weight than someone who is dieting but not taking a GLP. This presents a catch-22. The GLP users are losing more weight, which is good, but more of the weight is muscle mass, which is bad, especially in an older population. Let’s use a hypothetical to illustrate the point better.

Shelly is a 45-year-old female who weighs 185 pounds. She wants to lose weight and goes on a low-carb diet but doesn’t exercise. After 12 weeks, she has lost 15 pounds. The amount of muscle mass lost is likely between 1.5 and 4.5 pounds.

Next, we have Shelly’s twin sister, Melly, who is the same age and weight but uses a GLP drug and doesn’t exercise either. Melly loses 20 pounds in the same time frame. Great! She’s lost more weight; the drug has clearly worked as planned. However, using the numbers from the study above, Melly has likely lost anywhere from 5.8 to 7.8 pounds of muscle.

6 to 8 pounds of muscle might not sound like much, but that is a considerable amount. One must remember that muscle is a very metabolically active tissue, especially compared to fat. Muscle tissue uses much more energy than fat, which increases a person’s resting metabolic rate and protects against type II diabetes and other metabolic disorders. Let’s also not forget all the strength lost in that 6 pounds. Putting on 6 pounds of muscle is no small feat, and for someone like Melly, it could easily take a year or more, even with a finely tuned diet and resistance training program.

Losing weight is great if that’s the goal, but losing the right kind of weight is even better.

Resistance Training To The Rescue!

Once again, resistance training is here to save the day. Is there anything lifting weights can’t do? It’s well known that people who lose weight via diet and exercise, including resistance training, have better outcomes than simply diet alone. Those who diet and exercise still lose some muscle mass, but not nearly as much as those who just eat less. Those who exercise while dieting also become stronger and have better body composition.

My message is this: should you choose to use a GLP 1 drug for weight loss, please, please, please make sure you’re doing some form of weight training while using. Adding muscle will always be more difficult than losing it, so don’t put yourself in a deficit by neglecting it.