Ozempic.  Wegovy.  Munjaro.  Semiglutides.  GLP-1s.  Whatever you call them, everyone is talking about weight loss medications.  They may help you lose weight, but no one is talking about what kind of weight you’re losing or why that matters.

We can break the mass in your body into two categories:  fat mass and lean mass.  Fat mass is the body fat we carry around.  We all need some fat to function properly - this is called essential fat.  Most of us carry around more than just essential fat, and as that amount increases, we are more likely to develop lifestyle related diseases, like Type II Diabetes and heart disease.  Lean mass can be broken into many subcategories, including bone mass, skeletal muscle mass, and more.  Higher amounts of lean mass are associated with greater longevity and physical performance, as well as reduced rates of chronic disease and frailty.  In short, lots of lean mass = good; lots of fat mass = bad. 

Weight Loss Through Diet and Exercise:

So what happens when we lose weight?  As much as we wish we could lose 10/20/50/100 lbs of just body fat, that isn’t how it works.  When you lose weight at the recommended rate of 1-2 lbs per week through diet and exercise, about 20-25% of the weight lost is lean mass.  Strength training can help you to retain as much lean mass as possible, but inevitably some will be lost.  

Weight Loss Through Medication:

One of the advertised perks of weight loss medications is that they help you drop pounds fast.  On it's face, this seems like a positive!  The faster you lose weight, the sooner you'll be healthy, right?  Unfortunately, when you lose weight quickly with a weight loss medication, you lose more lean mass than if you lose it at a controlled pace through diet and exercise alone.  How much?  We’re not quite sure yet.  The more robust and high quality studies are suggesting 40-50% of the weight lost is lean mass, and some experts are claiming even more.  

Let’s do some math to better understand why this is concerning.  Say we have two women, each weighing 300 lbs with a body fat (BF) percentage of 45%.  At 45% body fat, they would be classified as obese. They each lose 100 lbs.  For this example, we’ll say that 25% of the weight lost through diet and exercise is lean mass, and with the assistance of weight loss medication, 40% of the weight lost is lean mass.

As you can see, while they lost the same amount of weight on the scale, Linda did not lose as much fat mass and is still clinically obese.  In addition, she lost significantly more lean mass, which puts her at risk for impaired physical performance with daily activities, loss of bone mineral density, and a state of frailty far earlier in life than expected.  She has essentially aged a decade or more in a fraction of the time.  

Armed with a better understanding of the unspoken side effects of these weight loss medications, you can follow one of two paths:  

1. Stick to the tried and true.  Consistency and hard work with diet and exercise pay off in the long run, with the only side effects being better health and function.  Losing weight can be a challenge (both mentally and physically), even if you "know how," or you’ve lost weight before.  If you're sick of getting on and off the weight loss roller coaster, we’re happy to help.  Our coaches and doctors are knowledgeable in improving body composition, and can also hook you up with an amazing dietitian or health coach to support you in your journey.  
2. If you use weight loss medication to kick start your journey, know that it is not a magic bullet or a get out of jail (or lifestyle change) free card.  In fact, it is even more important for you to make lifestyle changes because of the side effects of the medication.  Strength training is a non-negotiable if you want to retain your lean mass.  Not only will this preserve your physical function and longevity, it will help you maintain your weight loss after you stop using the medication (more lean mass = higher metabolism).

Informed consent is a must with any medical decision.  The challenge for providers and patients alike is that the information regarding these medications is evolving on a daily basis.  What you read online or were told by your doctor 6 months ago may or may not still be true in light of new research.  What isn't evolving is the fact that strength training is key to longterm health and weight management, regardless of if you use a medication or not.  

Questions or comments?  Let me know!  [email protected].

Want to dive into the data? 

A systematic review of the effect of semaglutide on lean mass: insights from clinical trials

A Review of the Effects of Glucagon-Like Peptide-1 Receptor Agonists and Sodium-Glucose Cotransporter 2 Inhibitors on Lean Body Mass in Humans

Incretin-Based Weight Loss Pharmacotherapy: Can Resistance Exercise Optimize Changes in Body Composition?