GLP-1 Drugs: Breakthrough or Band-Aid?
GLP-1 drugs such as Ozempic and Wegovy (semaglutide), and related drugs such as Mounjaro and Zepbound (tirzepatide), have transformed the treatment of obesity and type 2 diabetes. They reduce appetite, improve blood sugar control, and can produce substantial weight loss. Semaglutide has also been shown to reduce major cardiovascular events in certain high-risk patients.
The results are impressive. But they also raise important questions. What happens when people stop taking them? How much muscle is lost along with fat? And what do these medications do—and not do—to improve underlying metabolic health?
Researchers and physicians including Robert Lustig, Ben Bikman, Nick Norwitz, and William Davis offer different perspectives on these questions.
How GLP-1 Drugs Work
GLP-1 is a hormone naturally released by the intestine after eating. It helps regulate blood sugar and appetite.
Drugs such as semaglutide mimic GLP-1. They increase insulin secretion when blood glucose is elevated, reduce glucagon, slow stomach emptying, and act on areas of the brain involved in appetite. People tend to feel full sooner, experience less hunger, and eat less.
Tirzepatide activates both GLP-1 and another hormone receptor called GIP and has produced even greater average weight loss than semaglutide in a head-to-head trial.
How Effective Are They?
The weight-loss results are substantial.
In major clinical trials, people taking semaglutide have lost about 15% of their body weight on average, while higher doses of tirzepatide have produced average losses of around 20% or more.
The benefits go beyond weight. These medications can substantially improve blood sugar control and other measures of metabolic health. Semaglutide has also reduced major cardiovascular events in certain people with overweight or obesity and established cardiovascular disease.
For people who have struggled with obesity or diabetes for years, these can be important benefits.
Different Views of GLP-1 Drugs
The success of GLP-1 drugs has produced an interesting debate among physicians and researchers whose work I follow.
Ben Bikman acknowledges their effectiveness but questions whether they address the underlying metabolic problems associated with chronically elevated insulin. He places greater emphasis on lowering insulin through diet and lifestyle.
Robert Lustig emphasizes the distinction between weight loss and metabolic health. He sees benefits from reducing visceral and liver fat but argues that improving metabolic health should be the goal, not simply losing pounds.
William Davis is more skeptical, particularly about loss of muscle and lean tissue. He believes dietary changes can address many of the metabolic problems associated with obesity.
Nick Norwitz offers an interesting counterpoint because he changed his mind. Initially skeptical, he became more enthusiastic after examining newer research suggesting that GLP-1 drugs may have benefits extending beyond weight loss and diabetes.
These different perspectives raise an interesting question:
Are GLP-1 drugs primarily powerful weight-loss medications, or will they eventually prove useful for a much wider range of health problems?
Muscle, Side Effects and What Happens When You Stop
One concern is loss of lean mass, including muscle, during substantial weight loss. Some lean-tissue loss normally accompanies weight loss, but preserving muscle may be particularly important for older adults.
Common side effects include nausea, vomiting, diarrhea and constipation. More serious complications are less common.
Weight regain is another concern. In a follow-up of a major semaglutide trial, participants regained about two-thirds of their lost weight within a year of stopping treatment.
On the other hand, these medications don't simply cause weight loss. Research with tirzepatide has also found improvements in insulin sensitivity and pancreatic beta-cell function.
Diet and Exercise Still Matter
Taking a GLP-1 drug doesn't make nutrition and exercise irrelevant.
Because these drugs substantially reduce appetite, people may eat much less food. Getting adequate protein and essential nutrients becomes important, particularly for maintaining muscle. Resistance exercise can also help preserve strength and lean mass.
For people with insulin resistance or type 2 diabetes, improving diet may provide benefits beyond simply eating fewer calories.
GLP-1 medications and lifestyle changes therefore don't necessarily have to be competing approaches. They can be used together.
Questions That Remain
GLP-1 drugs are changing the treatment of obesity and type 2 diabetes, and research into their effects continues to expand.
The benefits can be substantial, but important questions remain about long-term treatment, muscle preservation, side effects, weight regain after stopping, and how these drugs affect metabolic health beyond weight loss.
The differing views of researchers and physicians such as Nick Norwitz, Ben Bikman, Robert Lustig, and William Davis make this an interesting area to follow as more evidence becomes available.
Learn More
Videos
A former skeptic explains why newer evidence substantially changed his view.
A strongly skeptical perspective, particularly concerned with muscle loss and underlying metabolic health.
Bikman explains why he believes the drugs can be effective without necessarily correcting underlying hyperinsulinemia.
Lustig discusses the benefits of GLP-1 drugs as well as concerns about muscle loss and metabolic health.
A practical discussion of nutrition for people using GLP-1 medications.