Several FDA-approved prescription medications can produce significant weight loss, ranging from about 10% to 20% of your body weight depending on the drug. Over-the-counter supplements, by contrast, have little reliable evidence behind them. The pills that actually work require a prescription and come with real tradeoffs in cost, side effects, and long-term commitment.
GLP-1 Medications: The Most Effective Option
The newest and most effective weight loss medications belong to a class called GLP-1 receptor agonists. These drugs mimic a hormone your gut naturally produces after eating, which signals your brain to feel full and slows down how quickly food leaves your stomach. The result is that you eat less without the constant battle against hunger.
Semaglutide (sold as Wegovy) produced an average weight loss of 13.7% of body weight over 72 weeks in clinical trials. Tirzepatide (sold as Zepbound), which targets two gut hormones instead of one, performed even better at 20.2% over the same period. For someone weighing 250 pounds, that’s roughly 34 to 50 pounds lost. Both are weekly injections, not traditional pills, though oral versions of semaglutide exist for diabetes treatment.
The most common side effects hit hardest in the first couple of months: nausea, reduced appetite, and sometimes vomiting. These typically fade as your body adjusts and the dose gradually increases. Serious complications like pancreatitis are rare. In one large semaglutide trial, only 3 out of 1,306 participants developed acute pancreatitis. Tirzepatide shows similarly low rates, around 0.3% to 0.4% across all doses studied.
Older Prescription Pills
Before GLP-1 drugs dominated the conversation, a handful of oral medications were the standard options. They produce more modest results but are genuinely taken as pills.
- Phentermine-topiramate (Qsymia) combines an appetite suppressant with a drug originally used for seizures and migraines. It reduces hunger through two different brain pathways and is one of the more effective older options.
- Naltrexone-bupropion (Contrave) pairs an addiction-treatment drug with an antidepressant. Together, they act on reward and hunger centers in the brain to reduce cravings.
- Orlistat (Xenical or Alli) works completely differently. Instead of suppressing appetite, it blocks your body from absorbing about 25% of the fat you eat. In a one-year trial, patients taking orlistat lost an average of 10% of their body weight compared to 6% for those on a placebo. Alli is the only weight loss pill available over the counter, at a lower dose than the prescription version.
Orlistat’s side effects are distinctive and worth knowing about upfront. Because undigested fat passes straight through your system, you can experience oily stools, urgent bowel movements, gas with oily discharge, and stomach pain. Eating a lower-fat diet significantly reduces these effects, which is partly how the drug encourages behavior change.
Who Qualifies for a Prescription
You can’t simply ask for these medications because you’d like to drop a few pounds. The standard criteria require a BMI of 30 or greater, or a BMI of 27 or greater if you also have a weight-related condition like high blood pressure or type 2 diabetes. A BMI of 30 corresponds to roughly 180 pounds for someone 5’5″ or 210 pounds for someone 5’9″.
These medications are approved for long-term use. You can keep taking them as long as you’re benefiting and not experiencing serious side effects, which matters because of what happens when you stop.
What Happens When You Stop
This is the detail most people don’t hear about until it’s too late. A systematic review published in The Lancet found that one year after stopping GLP-1 medications, people regained 60% of the weight they had lost during treatment. The drugs work by changing your hunger signals and metabolism while you’re on them, but those effects don’t persist once you stop.
That means these medications function more like blood pressure drugs than antibiotics. They manage the condition rather than cure it. If you lose 40 pounds on semaglutide and stop taking it, you can expect to regain roughly 24 of those pounds within a year. This makes the decision to start one a long-term commitment, not a quick fix.
The Cost Problem
GLP-1 medications are expensive. Wegovy and Zepbound both cost $499 per month when purchased directly from the manufacturers without insurance, with Zepbound’s starting dose available at $349 per month. Insurance coverage varies widely. Some plans cover these drugs for obesity, others only cover them for diabetes, and many don’t cover them at all.
The older oral medications tend to be cheaper, especially generic versions of phentermine or orlistat. But even with lower costs, the ongoing nature of treatment means the expense adds up over months and years.
Over-the-Counter Supplements
The Mayo Clinic puts it plainly: little proof exists that any dietary supplement can help with healthy, long-term weight loss. The studies that do exist are typically small, short, and use combination products that make it impossible to identify which ingredient (if any) produced results.
One frequently cited trial gave participants a supplement containing raspberry ketone, caffeine, bitter orange, ginger, and garlic root extract. The supplement group lost 4.2 pounds over eight weeks compared to 0.9 pounds for the placebo group. That sounds promising until you consider the trial had only 45 participants, lasted just eight weeks, and used a multi-ingredient blend. Those results can’t reliably predict what would happen in the real world over a meaningful time frame.
Products marketed as fat burners, metabolism boosters, or appetite suppressants fill entire aisles at pharmacies and health stores. Unlike prescription drugs, supplements don’t need to prove they work before being sold. They only need to avoid being actively harmful. The gap between marketing claims and clinical evidence is enormous for virtually every weight loss supplement on the market.
Comparing Your Realistic Options
If you meet the BMI criteria, the choice comes down to how much weight you need to lose, what you can afford, and what side effects you’re willing to tolerate. GLP-1 drugs produce the most dramatic results but cost the most and require injections. Older oral medications like Qsymia and Contrave offer moderate weight loss in pill form at a lower price. Orlistat (as Alli) is the only option you can buy without a prescription, but its results are modest and its digestive side effects are hard to ignore.
No pill replaces the basics of eating patterns and physical activity. Every clinical trial of weight loss medication includes lifestyle changes alongside the drug, and the drug’s results are measured on top of those changes. The medications make it easier to eat less by reducing hunger or fat absorption, but they work best as one part of a broader approach rather than a standalone solution.