Sheila Baylis is an Editor for PEOPLE's Health vertical; she contributes to print features and directs the digital Health team on stories ranging from the COVID-19 pandemic to body image and women's health. She has a Master's Degree in Gender Studies.
The obesity drug Wegovy was approved by the FDA in 2021, and since then, it’s become a trending topic on social media and popular among celebrities for weight loss.
Some doctors have expressed frustration that Wegovy and its counterpart Ozempic, which is prescribed for diabetes, aren’t getting to people who need them, and the FDA has listed a shortage for both drugs.
The intended patient population for Wegovy is people with chronic obesity, and Ozempic is for those with type 2 diabetes. As many as 80% to 90% of individuals with type 2 diabetes struggle with obesity as well.
PEOPLE spoke with Ania Jastreboff, M.D., PhD., an obesity medicine physician scientist at Yale University, who is trained as both an adult endocrinologist and a pediatric endocrinologist, to better understand these drugs. Jastreboff spends the majority of her time studying these medications — how they work and who they work for — and then caring for patients with obesity.
Are Wegovy and Ozempic the same drug?
They are both semaglutide. Semaglutide is branded as Ozempic for the treatment of type 2 diabetes, and semaglutide is branded as Wegovy for the treatment of obesity. It is the same molecule that is used for both indications.
Semaglutide Ozempic for diabetes goes up to a dose of two milligrams once-weekly, and semaglutide Wegovy for obesity goes up to a once-weekly dose of 2.4 milligrams.
So obesity is a disease?
Obesity is a neurometabolic disease. It is a chronic, treatable disease. We really need to treat obesity as we treat any other chronic disease, with effective and safe approaches that target underlying disease mechanisms.
We can understand obesity as a disease in this way: Our body has this concerted interest in carrying a certain amount of energy, and it needs to carry that energy in order to not starve, and it also needs to carry that energy in order for our body to function well. The way that it stores that energy is by fat. So, it carries energy by carrying fat. So, our body has this sweet spot whereby it does not want to carry not enough fat, but it also doesn't want to carry too much fat.
We call that sweet spot the defended fat mass set point … and it's set by our brain which receives continuous signals via hormones in our body that are released by our gut and by our pancreas when we eat. Those hormones communicate with our brain, and they inform our brain how much energy or how much fat we are carrying. Then our brain determines, 'Okay, how much of that should we carry?'
So people with obesity have a higher set point?
Yes, the defended fat mass set point is elevated. So, in order to treat obesity, we have to have interventions that target the pathophysiology, that target the mechanisms underlying obesity, and decrease that defended fat mass set point back down, or another way of saying it, they re-regulate that defended fat mass set point to a place that is healthier.
There are many different types of obesity. We are just not at a place yet where we have biomarkers or ways to differentiate the different types of obesity. So, just as there are different types of diabetes, there are also different types of obesity.
How do the medications work?
They work in the brain. So, what we think the medications do is that they decrease that defended fat mass set point, and a consequence is that we lose weight. This is an important distinction because the medications, we believe that they work in the brain.
Are Wegovy and Ozempic appetite suppressants?
No. Semaglutide and other medications in this class are nutrient-stimulated, hormone-based medications.
These medications are working in a way to mimic those hormones that are released from our intestine and our pancreas when we eat, then impact different tissues in our body. One of the targets is the brain. So, they work in the brain to impact satiety. So, what happens is when patients take these medications, they feel more full earlier, especially during the weight-reduction phase.
What is the weight-reduction phase?
So, when a patient starts taking this medication, their defended fat mass set point is reduced, and during the weight-reduction phase, they are seeking to get to that new defended fat mass.
Once they reach that new set point, what happens is that their appetite, their cravings may come back, but the weight does not come back. So, basically, and this is critical because if somebody says, 'Well, this is an appetite suppressant' or somebody says, 'This is a weight loss drug,' that's not accurate to say because it's an anti-obesity medication because it's treating the disease. You're going to reach a weight plateau and stop losing weight, but the medicine is still working and defending the new set point.
And what happens if you stop taking Wegovy after you have lost weight?
Not everybody needs the highest dose, but if you want to maintain the weight reduction that you achieved, you have to continue taking the medication. The reason for that is because obesity is a chronic disease.
If you have a patient who has high blood pressure, they have hypertension, and you start them on an antihypertensive medication, and their blood pressure improves, what would happen if you stopped that medication? Well, their blood pressure would go back up — and we're not surprised. It's the same with anti-obesity medications.
[Expecting a patient with chronic obesity to lose weight through willpower] is akin to having a patient with diabetes and thinking that they can concentrate really hard to bring their blood sugars down. You can't do that, and with obesity, our patients can't use their prefrontal cortex for the rest of their lives to impact every morsel of food that they eat. So, it's not in our control. Once that set point is elevated, you need treatment.
So, Wegovy does not teach the brain to be at that new set point for the long-term by itself, without the drug.
Right. It re-regulates your defended fat mass set point, but only while you're taking the medication.
Are semaglutides safe for long-term use?
This class of medications have been used for the treatment of type 2 diabetes for over a decade-and-a-half. These medications have more recently been approved for obesity treatment, but these molecules were FDA-approved previously.
What are the side effects?
The most common side effects with these medications are nausea and diarrhea, and sometimes you can have vomiting or constipation. Depending on the patient and how they respond, there are many ways to mitigate those side effects.
It's very important to always start at the lowest dose when you're starting these medications in a person who hasn't taken them, but it's always important to start at the lowest dose and to go up slowly. If the medication is increased too quickly, then these side effects are more likely to occur. We also know that a majority of the side effects occur during that dose escalation phase.
How can someone determine if they are a candidate for these drugs?
I think patients need to work with their provider to evaluate and assess their obesity, their degree of obesity, and what treatments may be best for them. Those treatments may include medications like the ones we're speaking about today. They may include bariatric surgery. So, those types of these treatments need to be discussed with patients' providers.
