The invention of drugs that meaningfully treat obesity is revolutionizing medicine. Medications such as semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound) have been shown to be safe and effective—and expensive. The expense, and sometimes the side effects, lead many people to wonder how long they need to stay on these medications.

First, let’s clear something up. I frequently get asked about “micro-dosing”, which surprisingly doesn’t have to do with psychedelic drugs. Apparently this comes up a lot when people are searching for affordable sources of weight loss drugs (and for simplicity I’ll call them all “GLP1’s”), or when they are watching videos of “wellness” influencers. The concept confused me at first because of my own experiences as a doctor.

“Micro-dosing” didn’t make sense to me because we always use the lowest effective dose of a medication. There is nothing special about calling that “micro-dosing'“—it’s simply how we do things. We give you the dose of blood pressure medicine that brings you pressure down to normal. By definition, giving you less than that isn’t enough; giving you more would be harmful. So let’s dispense with this whole “micro-dosing” concept as redundant and confusion.

What we really need to know is what happens to a patient when they cut down on or stop a GLP1? If they maintain lifestyle changes such as regular exercise and healthy eating, can they keep the weight off?

Let’s first acknowledge what most of us know from experience—while healthy eating and regular exercise make us feel better and live longer, they don’t lead to enduring, significant weight loss. In general, maintaining the modest weight loss from diet and exercise (about 5% of starting body weight on average) requires staying with some sort of formal supervised program. And the body will adjust to your new lifestyle in ways that make it hard to lose further weight and to maintain your weight loss. But this can potentially bury two important points: healthy eating and exercise improve health regardless of weight loss; and some people are actually successful with this strategy alone.

The 5% average loss of body weight with lifestyle interventions is nice, but a recent 2 year study showed that tirzepatide can lead to about 20% loss of starting weight. This study went on to ask two important questions: if, after losing the weight, we lower the dose, can we keep off the weight; and if we stop the medication completely, what happens?

The most successful strategy for keeping off the weight was staying on the maximal tolerated dose of the medication. When people stopped the medication (by being randomized to the placebo group) they returned to their starting weight (or nearly so, as they were given “rescue” tirzepatide if their weight gain reached a certain point). People who were taken down to a low dose of the medication did not do as well as the high-dose group, but still had substantial, durable weight loss, much more than we see with lifestyle change alone. Other studies have shown that the weight gain we see after stopping a GLP1 happens regardless of lifestyle changes (and to hammer the point home again, exercise and diet are very important regardless of weight!).

Speaking of exercise, I am frequently asked about loss of muscle mass with GLP1’s and I don’t have good answers—some studies show significant loss of muscle mass, whereas other studies show that GLP1’s lead to more fat loss than muscle loss. Either way, the recommendation is the same—exercise and eat a healthy diet (such as a Mediterranean diet)—and don’t skimp on dietary protein (try not to use supplements for protein needs).

As we gain more experience with GLP1s we are learning more about them and about obesity. While the weight loss is obvious the most visible effect of these medications, they improve health in other ways as well. Exactly how they improve heart risk, kidney disease, and metabolic liver disease isn’t clear but it isn’t entirely due to weight loss.

Obesity is a serious metabolic problem—it is not a failure of “correct” behavior. Studies of GLP1’s have really driven this home, as we see that people who come off the meds gain weight even having made substantial lifestyle changes. We need to move away from a hyper-moral approach to obesity, one that blames the individual for not being “strong enough” to cure themselves without medication. Weight loss medications are not a “cheat”—they are a critical tool used to treat an endemic medical problem.