There’s no doubt that the GLP drugs Ozempic, Wegovy and Mounjaro can make you lose a lot of weight and that the weight loss persists for at least 2 years, which is how long the research trials have lasted. The big question is how long will weight loss persist after 2 years.
Best-Case Scenario
The best-case scenario would be that you could take the medication until you reach a desirable weight, stop it and the weight would stay off. Research shows that if you discontinue the medication after a few months and make no other changes, you will probably regain most of the weight you lost. The same thing happens when you lose weight by dieting. If you go back to eating normally and make no other changes, you usually regained the weight you lost.
The body behaves as if it has a set-point that governs your body weight. If your weight falls below this set-point, your body fights back and tries to regain the weight you lost. Your metabolism slows down and your appetite increases, making you eat more than you burn off. Folks who lose weight by dieting usually regain about half the weight they lost within a year.
However, there are important exceptions to this generalization: A minority of dieters succeed in losing a lot of weight and keeping it off. Studies show that people who lose more than 10 percent of their body weight and keep it off for years have one thing in common: they walk or run for exercise, and they do it a lot–the equivalent of an hour a day of walking or a half hour of running.
One of the problems with being overweight is that it makes weight bearing exercise harder. It stresses your muscles, reduces your endurance and causes your joints to ache. The unpleasantness associated with weight bearing activity sets up a vicious cycle: the more weight you gain, the less walking or running you want to do; and the less walking or running you do, the more weight you gain.
The good news is that the opposite is true. When you lose weight, it’s easier to exercise, which promotes more weight loss. If you use the weight you lose from taking a GLP-1 medication as a “bridge” to a vigorous walking or running routine, you may be able to keep the weight off even if you stop the medication.
Next-Best-Case Scenario
The next best scenario would be that, while you might not be able to stop the medication, the weight would stay off as long as you keep taking it. In research trials, weight loss from Ozempic, Wegovy and Mounjaro lasted until the studies ended after 2 years. To date there are no published studies on the results after 2 years.
Some specialists have expressed the opinion that the drugs will probably need to be taken for life. Obesity causes long lasting changes in the body that make it difficult to maintain weight loss. When you gain a lot of weight, fat builds up in places it normally wouldn’t be, including muscle cells, which makes them resistant to the effects of insulin. Consequently, the pancreas has to produce more than normal amounts of insulin to control the blood sugar, and excess insulin makes you gain weight. The fat in muscle cells doesn’t go away immediately upon losing weight; it sticks around for months or maybe years, which makes you tend to regain the weight you lost.
However, research shows that if weight loss is maintained long enough, muscle cells eventually regain their sensitivity to insulin. If weight loss can be maintained for several years, especially if it is used as a bridge to exercise, it is possible that medication will no longer be needed.
Of course, if you stopped the medication and started regaining weight, you could always go back to taking it again.
Worst-Case Scenario
A less attractive outcome would be that the medication would stop working after a couple years and you would regain the weight you lost even if you kept taking it. While many medications continue to work as long as you keep taking them, the body develops a “tolerance” to others, which causes them to lose their effectiveness over time. Tolerance can often be overcome by increasing the dose of the medication. However, it is possible that if taken long enough these drugs could lose their effectiveness altogether.
Currently there are no published data on the effectiveness of GLP-1 medication for maintaining weight loss beyond 2 years. A hopeful sign is that the effectiveness of GLP-1 drugs for treating diabetes–not necessarily for obesity–continues as long as the medication is taken.
