Ozempic has become one of the most widely used weight-loss treatments in modern medicine. Capable of helping some patients lose up to 15 percent of their body weight, it has surged in popularity across the United States, generating billions in annual sales and drawing attention from both the medical community and celebrities.

Yet behind the hype lies a more uncomfortable truth. While the number on the scale may drop quickly, Dr. Jason Fung, renowned kidney specialist and bestselling author of “The Diabetes Code,” said in an episode of Vital Signs on that not all weight loss is created equal.

In his view, the real question isn’t just how much weight you can lose but what type of weight you are losing—and can you keep it off?

True success, he said, means burning dangerous fat, preserving muscle and strength, avoiding loose skin and a gaunt “Ozempic face,” and building lasting metabolic health—not just chasing a temporary number on the bathroom scale.

How Ozempic Works

Ozempic contains semaglutide, which belongs to a class of medications called GLP-1 receptor agonists. GLP-1 stands for glucagon-like peptide-1, a hormone that helps regulate blood sugar and appetite. By mimicking this hormone, semaglutide can increase feelings of fullness after meals, so many people naturally eat less and reduce their calorie intake.

“GLP-1 makes you feel full,” Fung said. The drug also slows gastric emptying and influences brain areas responsible for appetite regulation, which can produce mild nausea as a side effect, resulting in slower food absorption and a blunted insulin response.

Feeling hungry leads people to consume more calories, which can cause weight gain. “So if you don’t affect the hunger, then you’re not going to affect the calories, because that’s sort of the root cause of the whole thing, and that’s why Ozempic is useful [for weight loss],” he said.

By reducing hunger, Ozempic helps people eat less, directly tackling the root cause of weight gain. This also explains why, when people stop taking Ozempic, the feeling of hunger returns, often leading to weight regain.

Not All Weight Loss Is Equal

At the core of Fung’s critique is a distinction that mainstream weight-loss approaches often ignore: The health impact of weight loss depends heavily on where the lost tissue comes from. He distinguishes between two types of body fat: subcutaneous and visceral.

Fat Loss

Subcutaneous fat lies beneath the skin and is relatively benign, stored where it belongs. Visceral fat, by contrast, accumulates around internal organs such as the liver and is far more dangerous from a metabolic standpoint as it is strongly linked to insulin resistance, Type 2 diabetes, cardiovascular disease, and fatty liver disease.

Visceral fat typically accumulates in the belly. “The fat, which is contained within the liver and the organs, is not supposed to be there,” Fung said. “The liver is not supposed to hold fat. So that fat is actually very dangerous fat, whereas the subcutaneous fat is not really particularly dangerous,” he said.

Rapid weight loss can often reduce subcutaneous fat, the layer under the skin that gives the face and body fullness. When this happens quickly, people may look gaunt or hollow, a phenomenon widely referred to as “Ozempic face.”

Relying on medication for weight loss does not allow patients to control where their bodies draw fat from, he said, leading to two common outcomes: “One is fats being pulled down from subcutaneous fat, which gives you that Ozempic face. And two, you’re not burning off the excess protein, so then you’re getting this sagging skin.” Ozempic doesn’t tell you what foods you should eat, or what’s healthy and what’s not, he added.

Muscle Loss

Ozempic’s appetite suppression can also cause muscle loss. Part of the problem, Fung said, is how the drug works: By increasing GLP-1 levels, it induces a strong feeling of fullness. Feeling full can lead people to avoid protein- and fat-rich foods—which activate satiety hormones—and instead choose ultra-processed carbohydrates that are less filling.

“You might wind up with a lot of weight loss, but not the good weight loss. Like, you might wind up in your Ozempic phase and lose a lot of muscle because you’re just not eating enough protein. So yeah, there could be some very bad effects.”

Muscle supports strength, posture, movement, blood sugar control, and healthy aging. If a weight-loss plan strips away too much muscle, a person may become lighter but less healthy.

Weight Often Returns After Stopping Ozempic

People who rely on Ozempic for weight loss often experience only temporary benefits, Fung said.

Studies suggest that people who stop taking the medication may regain around 60 percent of the weight they lost within a year. The pattern of rebound weight gain is common enough to be considered the norm. “When they come off it, they pretty much gain all their weight back,” Fung said.

He attributed this largely to a lack of proper education during treatment. Many patients, he said, receive little to no guidance on nutrition, healthy habits, or long-term weight maintenance. Instead, their experience may consist of “a five-minute online interview without a real doctor—basically a bot,” which becomes the extent of both their medical and nutritional support.

As a result, when patients stop the medication and the side effects—such as nausea—subside, their appetite returns without any framework for managing it. “They didn’t know how to deal with it,” he said, noting that most people simply revert to their previous eating patterns and lifestyle habits.

In rare cases, some people adopt healthier habits during treatment and successfully maintain their weight loss. But realistically, he added, “most people just regain all the weight.”

Ozempic for Type 2 Diabetes

Ozempic plays an important role in treating Type 2 diabetes, particularly for patients who have had the condition for years, are on multiple medications, and are significantly overweight. In Fung’s practice, he prescribes it for more severe cases, always combining it with dietary guidance focused on healthy proteins, vegetables, and fats rather than processed foods and sugary drinks.

However, long-term use is challenging for most people. Side effects, especially persistent nausea, often become too difficult to tolerate. “You might handle it for a year while losing weight and getting compliments,” Fung said, “but five years later, when the novelty wears off, and you’re still nauseated, it gets much harder.”

Real-world data from a systematic review and meta-analysis published in the Journal of Managed Care & Specialty Pharmacy reflect the challenge: Only about 27 percent of patients on GLP-1 drugs for obesity remain adherent after one year, with rates of around 47 percent for semaglutide. In his unhealthier patient population, Fung often works to keep people on the medication rather than stopping it, yet most eventually discontinue due to side effects.

“Most people don’t wind up staying on it,” he said, “because the side effects are quite difficult to take long term.”

Dietary Alternatives That Work With Your Hormones

As an alternative to medication-dependent weight loss, Fung favors more sustainable weight-loss strategies that target visceral fat, preserve muscle, and minimize loose skin.

One approach he often points to is low-carbohydrate eating, which, he says, naturally boosts GLP-1—the same satiety hormone Ozempic mimics—especially when it includes enough protein, healthy fats, and fiber, all of which lower insulin levels and reduce hunger in a more balanced way. Unlike refined carbohydrates and junk food, which provide almost no fullness signals, real foods help you eat less without feeling deprived.

“If you eat a low-carbohydrate diet, then you’re eating more of the proteins and the fats and the things that are going to stimulate more of this GLP-1 and therefore create more satiety, and ... make you eat less in the long term,” Fung said.

Fiber may also help by supporting satiety signals in the gut. When fiber is broken down in the colon, it produces short-chain fatty acids that may help stimulate GLP-1 release, Fung said. A well-designed diet can work alongside the body’s appetite system rather than fight it.

Intermittent fasting, on the other hand, triggers a distinct hormonal response—lower insulin levels and encourages the body to burn deep visceral fat first, Fung said.

Fung frames sagging skin as a protein issue rather than a fat issue. Skin and connective tissue are made of protein, so simply losing fat does not remove excess skin. Fasting, he said, activates autophagy, the cellular “cleanup” process that helps break down damaged proteins and cellular components.

Fasting also raises growth hormones, which help protect muscle mass during weight loss. “You’re pumping up your growth hormone to very high degrees,” Fung said. “That’s going to help prevent that sort of muscle loss.”

Fasting reduces insulin, which primarily targets visceral fat, and simultaneously triggers autophagy, which helps break down excess protein in the skin and connective tissue.

The goal is not one perfect diet for everyone. The goal is a way of eating that reduces hunger, supports muscle, and is sustainable over time—factors that make weight loss more likely to last.

A Balanced View on Ozempic

Ozempic has changed the conversation around obesity. It has made appetite biology impossible to ignore and brought weight loss science into mainstream medicine.

Fung acknowledges that Ozempic can be valuable for certain patients—those with severe obesity, long-standing Type 2 diabetes, very high insulin levels, or complications such as fatty liver and kidney disease—especially when diet and lifestyle changes alone have not been enough.

Even then, he recommends combining the drug with proper education on healthy eating, focusing on protein, vegetables, and healthy fats, so patients can build lasting habits while their hunger is under control.

“The hope is that it kicks down the hunger so you can make changes in your habits, your mindset, and your life—like becoming more active,” he said.

Ozempic produces a “supraphysiologic” effect on GLP-1—far beyond what food can naturally achieve, Fung said. While proteins, fats, and fiber mildly boost GLP-1 and satiety, the drug dramatically amplifies these effects, which helps explain its strong impact on appetite and weight.

For particularly younger or otherwise healthy people who want to lose just a few pounds, the risks likely outweigh the modest, temporary benefits.

“I’m not against it,” he said, “The problem is that everything in medicine comes down to a risk versus benefits. … There’s a time and a place for that. In that time and place, the benefits outweigh the risk.”