You can take several FDA-approved prescription medications, one over-the-counter drug, and a handful of supplements with modest evidence behind them. The options range from weekly injections that produce 13 to 20% body weight loss to fiber supplements that may help you feel full before meals. What’s available to you depends largely on your BMI, your health history, and whether you’re looking for a prescription or something you can buy on your own.
GLP-1 and GIP Injections
The most effective weight loss medications currently available are injectable drugs that mimic gut hormones involved in appetite regulation. These work by targeting areas of the brain that control hunger and food intake, making you feel satisfied sooner and reducing the mental noise around food.
Tirzepatide (Zepbound) mimics two gut hormones simultaneously and produced an average of 20.2% body weight loss over 72 weeks in a head-to-head clinical trial published in the New England Journal of Medicine. Semaglutide (Wegovy), which mimics one of those same hormones, produced 13.7% loss over the same period. For someone weighing 250 pounds, that translates to roughly 34 to 50 pounds. Both are given as weekly self-injections and are approved for long-term use.
An older drug in the same class, liraglutide (Saxenda), works through the same mechanism but requires daily injections and typically produces less weight loss than the newer options.
Prescription Pills
If injections aren’t appealing or accessible, there are oral prescription options, though they generally produce more modest results.
Phentermine-topiramate (Qsymia) combines an appetite suppressant with a medication originally developed for seizures and migraines. The combination may make you less hungry or help you feel full sooner. It’s approved for long-term use. Phentermine alone is also available, but it’s only approved for short-term use of a few weeks and is off the table for people with a history of heart disease, uncontrolled high blood pressure, hyperthyroidism, or glaucoma.
Naltrexone-bupropion (Contrave) pairs two existing medications that, individually, treat addiction and depression. Together they appear to work on both the brain’s appetite center and its reward system. Bupropion stimulates cells in the brain that signal fullness, while naltrexone blocks a feedback loop that would normally shut those cells down. The combination reduces food intake more than either drug alone, and it may be particularly helpful if you experience strong food cravings or emotional eating patterns.
Who Qualifies for Prescription Medications
Prescription weight loss drugs are generally available to people with a BMI of 30 or higher. If your BMI is 27 or higher and you have a weight-related health condition like controlled high blood pressure, type 2 diabetes, or high cholesterol, you may also qualify. Your doctor determines which medication fits your health profile, since each one carries different contraindications and side effects.
The One Over-the-Counter Drug
Orlistat is the only FDA-approved weight loss medication you can buy without a prescription. Sold as Alli at a lower dose (and as Xenical at prescription strength), it works in your gut rather than your brain. It blocks about 30% of the dietary fat you eat from being absorbed, so that fat passes through your body instead of being stored.
The trade-off is real: eating a high-fat meal while taking orlistat can cause oily stools, gas, and urgent bowel movements. Most people learn quickly to keep fat intake moderate. The weight loss is modest compared to the injectable medications, but orlistat remains the only option that doesn’t require a doctor’s visit.
Fiber Supplements
Glucomannan, a soluble fiber derived from the konjac root, is one of the better-studied natural weight loss supplements. It absorbs a remarkable amount of water in your stomach, forming a gel that slows digestion and helps you feel full. The typical approach is taking it dissolved in water about 30 minutes before each main meal.
Studies have used around 1 gram of glucomannan per meal, often combined with other fibers like inulin and psyllium for a total of about 5 grams per dose. The weight loss from fiber supplements is modest, and it works mainly by helping you eat less at meals rather than changing your metabolism. Drinking plenty of water with it is important, since the fiber expands significantly.
Caffeine and Green Tea Extract
Caffeine does increase your metabolic rate, but the effect is small. In controlled testing, caffeine boosted calorie burning by about 6% over a four-hour window compared to a placebo. That amounts to roughly 18 extra calories burned per hour, which is meaningful only if it compounds over months and isn’t offset by eating more.
Green tea extract, despite its popularity in weight loss supplements, has not shown a statistically significant thermogenic effect beyond placebo in controlled studies. Where green tea extract does warrant caution is liver safety. The European Food Safety Authority concluded that concentrated green tea extracts delivering 800 mg or more of the active compound EGCG per day can cause liver damage. Several case reports document liver injury at doses found in common weight loss supplements. Drinking brewed green tea is generally safe; concentrated extract capsules are a different story.
Supplements That Don’t Work
Vitamin B12 injections are widely marketed for weight loss and energy, but there is no solid evidence they help you lose weight. Unless you’re actually deficient in B12, supplementation won’t boost your energy or improve exercise performance. Deficiency is worth checking for on its own merits, but the injections offered at weight loss clinics are largely a placebo for people with normal levels.
The broader supplement market is full of products combining various herbs, amino acids, and extracts with bold claims and thin evidence. The supplement industry doesn’t require proof of effectiveness before selling a product, only that the ingredients are generally recognized as safe. If a supplement promises dramatic weight loss, the results in actual clinical trials are almost always disappointing.
What Actually Moves the Needle
Every prescription weight loss medication is approved as an addition to a reduced-calorie diet and increased physical activity, not as a replacement for them. The medications make it easier to eat less by reducing hunger, blocking fat absorption, or quieting food-related thoughts. They don’t work if your eating patterns stay exactly the same.
For most people, the practical decision tree looks like this: if you have 10 to 15 pounds to lose, dietary changes and exercise are your primary tools, and a fiber supplement before meals may help at the margins. If you have significantly more weight to lose and meet the BMI thresholds, prescription medications can produce substantial results that diet alone rarely achieves. The injectable GLP-1 and GIP drugs represent the biggest leap forward in weight loss pharmacology in decades, but they require ongoing use to maintain results, and stopping them typically leads to weight regain.