The GLP-1 and GIP weight loss medications have simply upended the medical community’s perspective on, and treatment of, individuals who are overweight or obese.  To some, these medications might sound “too good to be true.” Others view them as the answer to their prayers. Still others view them as a shortcut or a quick fix. Many are left wondering, given the effectiveness of these drugs, if exercise is even necessary anymore. In this article, we’ll dive into how all of these perspectives are slightly misguided. Most importantly, we’ll discuss what the rapidly evolving scientific research suggests on these perspectives.

 

Who Are Weight Loss Medications For? How Do They Work?

It’s important to understand these weight loss medications are not for losing “those last 10-15 pounds,” or getting your “beach bod” for your cruise to the Mediterranean next summer. These medications are for individuals who meet specific clinical criteria. A body mass index (BMI) of > 30 without additional health risks (heart disease, diabetes, etc.) or a BMI of > 27 with additional health risks is the minimal threshold for these medications. 

It should be noted that just because an individual meets the clinical criteria for these medications does not mean that insurance plans will cover the cost of the medications. Nationally, less than a quarter of insurance plans cover these medications. With a hefty price tag of more than $1000/month, out of pocket costs can be a big barrier, even if the medication is clinically indicated. 

In terms of how these medications work, we won’t go into great depth as there are many resources out there that do (including this American Medical Association article), but the basic mechanism is they act on parts of your brian to make you feel fuller. They also slow down the digestion process, this further contributes to the “fullness” effect. Finally, there is some research that suggests that these medications reduce urges, not only for eating, but for other potentially addictive behaviors

 

Do Weight Loss Medications Work?

Overall, the effectiveness of these medications seem to be very significant. Most individuals lose at least 5% of their body weight (which is considered clinically significant enough to improve health), with some individuals losing 10-15% of their weight on medications like Wegovy (semaglutide), and > 20% of their body weight on the new generation medications like Zepbound (tirzepatide)

What are the Side Effects of Weightloss Drugs?

The medications aren’t without their side effects. Most common side effects are nausea, vomiting, diarrhea, abdominal pain and constipation. More severe side effects can occur depending on the individual. While not a side effect, per se, but definitely a consideration, these medications do have to be taken continuously to derive benefits. As soon as you stop taking the medication, hunger levels will return to normal and weight will be regained. 

In short, these medications seem moderately to highly effective for the vast majority of individuals who meet the clinical criteria for their use. They’re not without their side effects (including cost and a lifetime of use), and as we’ll discuss below they’re not a substitute for the health-enhancing effects of exercise.  

 

The Overall Role of Exercise While on Weight Loss Medication

While these medications are clearly effective at aiding in significant weight loss, it’s important to remember that body composition is only one singular component of overall health. Improving health is not just a byproduct of form (body weight), but also a byproduct of function; that is the body’s overall functional capacity. While achieving a healthier body weight can certainly improve functional capacity, a significant amount of research suggests that body weight is independent of functional capacity and health. 

The strength of muscle and bones plays an incredibly significant role in health, as does aerobic capacity. Improving muscular and aerobic capacity will not come from weight loss and it is certainly not the goal of weight loss medications. If anything, the weight lost from taking these medications provides the opportunity for individuals to engage in exercise to improve their functional capacity much more easily. 

A lower body weight makes physical activity less labor-intensive. Beyond that, since these medications reduce appetite so much, individuals report a significant reduction in pervasive thoughts about food. When this happens, greater mental bandwidth can be shifted towards other activities, such as physical activity and exercise. 

Beyond all the additional physical health benefits of exercising while on weight loss medications, there are significant mental health benefits. Research demonstrates that individuals who exercise have reduced depression and anxiety, improved overall mood, and higher energy levels. All of these mental health benefits are not only critical to overall health, but are especially important when individuals are in the energy-reduced state that weight loss medications induce. 

Finally, significant evidence suggests that exercise can result in up to 5% of body weight lost. This additive benefit of exercise just enhances the already potent weight reducing effects of these medications.

 

The Role of Exercise on Muscle and Bones Loss while on Weight Loss Medications

One concern that has emerged around taking weight loss medications is the significant amount of lean mass loss that seems to occur. Some research suggests that up to 40% of the weight lost taking these medications comes from what’s referred to as “lean mass.” A simple definition of lean mass is any tissue in the body that is not fat. Meaning muscle, bone, organ, and water weight. 

Since a lot of the research on these medications is still in its infancy, it’s unclear exactly where the lean mass loss is coming from, but there’s good reason to believe that a decent portion of it is coming from muscle mass. 

Loss of lean mass (and even muscle mass) is not entirely unexpected. Whenever large amounts of body weight are lost, the body simply needs less lean mass, because it’s supporting less weight overall. That being said, it’s also clear that a significant loss of muscle mass can reduce strength and functional capacity, which presents its own unique health concerns. Research suggests that low levels of muscle mass and muscular strength are significant predictors of reductions in functional capacity and health. Furthermore, significant loss of weight can also reduce bone mineral density, increasing the risk for osteoporosis. 

All of this to say that although these medications seem to be very effective at helping lose significant amounts of weight, large portions of the weight lost comes from lean mass, which is a threat to functional capacity and overall health. A properly constructed resistance training program can go a long way to combating loss of muscle and bone mass and strength. 

 

Resistance Training while on Weight Loss Medications

Resistance training may be the best exercise modality to compliment the use of weight loss medications. First and foremost, a properly designed resistance training program can limit loss of muscle size and strength, and aid in maintaining bone mineral density. Secondly, resistance training workouts typically result in lower calorie expenditure (compared to aerobic exercise), this is advantageous when someone is in a calorie reduced state, which is exactly the state weight loss medications put individuals in. 

This doesn’t mean you need to turn into a bodybuilder or strong (wo)man when you get on weight loss medications. Even as little as 1-2 days per week of resistance training can significantly improve muscle mass and strength, as well as maintain bone mineral density. The net effect being an increase in functional capacity as a result of both weight loss AND getting stronger. This is the best of both worlds and the way to optimize the effectiveness of weight loss medications, while minimizing the downside. 

Below is an example of a resistance training program our certified coaches at AFS may prescribe someone who is looking to start an exercise program in conjunction with the use of weight loss medications. Every new AFS member meets with a coach who designed a program specifically catered towards their fitness goals (schedule a meeting with a coach)

 

Not Weight Loss Medication OR Exercise, but Weight Loss Medication AND Exercise

The manufacturers of weight loss medications all state, as part of their clinical guidelines, that these medications should be taken in conjunction with an exercise program and other lifestyle modifications. Even the companies that profit from these very potent medications realize the potency of exercise to enhance the effectiveness of the medications and improve overall health and functional capacity. 

A well-rounded exercise program, incorporating both resistance and aerobic exercise is preferred. That being said, resistance training seems to play a key role, while taking these medications, in reducing the side effects of muscle and bone loss while improving strength and functional capacity. Prioritize resistance training, based on the recommendations made in this article. Doing so will help you maximize the benefits and minimize the risks of weight loss medications.

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