The most effective options for weight loss fall into three categories: prescription medications, over-the-counter drugs, and dietary supplements. Prescription medications produce the largest results by far, with newer injectable drugs helping people lose 15% to 25% of their body weight in clinical trials. Supplements and over-the-counter options exist but deliver far more modest effects. What you can actually take depends on your starting weight, your health history, and what your doctor is willing to prescribe.
Prescription Injections: GLP-1 Medications
The biggest shift in weight loss treatment over the past few years has been the arrival of GLP-1 receptor agonists, a class of injectable medications originally developed for type 2 diabetes. These drugs mimic a gut hormone that signals fullness to your brain, slows digestion, and reduces appetite. The two major names are semaglutide (sold as Wegovy) and tirzepatide (sold as Zepbound).
Tirzepatide produced a mean 25.3% body weight loss over 88 weeks in the SURMOUNT-4 trial, meaning someone starting at 250 pounds could expect to lose roughly 63 pounds. Semaglutide typically produces slightly less weight loss than tirzepatide, though both far exceed what older medications can do. These are weekly self-injections, not pills, and they require an ongoing prescription.
The downside is real. Gastrointestinal side effects hit roughly 50% to 60% of patients, especially early on. Nausea, vomiting, diarrhea, and constipation are common during the first weeks as your body adjusts and your dose gradually increases. These symptoms are dose-dependent and usually fade over time, but some people find them difficult enough to stop treatment. There are also concerns about muscle loss during rapid weight loss, which is why resistance training is strongly recommended alongside these drugs.
Prescription Pills
Before GLP-1 injections became widely available, oral prescription medications were the standard approach. They still have a role, particularly for people who don’t qualify for or can’t access the newer drugs.
Phentermine-topiramate (brand name Qsymia) combines an appetite suppressant with an anti-seizure medication that also reduces hunger. It’s taken as a daily capsule, with the dose gradually increased over several months. Clinical trials show average weight loss in the range of 7% to 10% of body weight, which is meaningful but well below what GLP-1 drugs achieve.
Naltrexone-bupropion (brand name Contrave) pairs an anti-addiction drug with an antidepressant. Together they act on brain pathways that control cravings and reward-driven eating. Weight loss results are more modest, typically around 5% to 8% of body weight. This option is sometimes chosen for people whose weight is closely tied to emotional eating patterns.
To qualify for any prescription weight loss medication, you generally need a BMI of 30 or greater. If your BMI is 27 or greater and you have a weight-related condition like high blood pressure or type 2 diabetes, you may also be eligible.
The One Over-the-Counter Drug
Orlistat is the only FDA-approved weight loss medication available without a prescription, sold under the brand name Alli at a 60 mg dose. It works differently from everything else on this list. Instead of suppressing appetite, it blocks fat absorption in your gut. When you take it with a meal, about 25% of the fat you eat passes through your body undigested.
The weight loss is modest, typically a few extra pounds over what diet alone would achieve. The side effects are directly tied to its mechanism: undigested fat has to go somewhere, so oily stools, gas, and urgent bowel movements are common, especially if you eat a high-fat meal. Most people find that these side effects naturally push them toward lower-fat eating, which may account for some of the weight loss itself. A higher-dose version (120 mg, brand name Xenical) is available by prescription.
Supplements That Claim to Help
The supplement aisle is packed with products marketed for weight loss, but the evidence behind most of them is thin or nonexistent. It’s worth knowing what the research actually shows for the most popular options.
Glucomannan is a water-soluble fiber derived from the konjac root. It absorbs water and expands in your stomach, which may slow gastric emptying and increase feelings of fullness. Some studies support a small effect on body weight, but results vary widely depending on the dose, study duration, and population studied. It’s generally safe but can cause bloating and digestive discomfort.
Chromium picolinate is one of the most heavily marketed weight loss supplements. The actual data is underwhelming. A meta-analysis of 19 clinical trials found that chromium supplementation decreased body weight by only 0.75 kilograms, roughly 1.6 pounds, over study periods lasting 4 to 24 weeks. The US Federal Trade Commission ruled back in 1996 that there was no scientific basis for claims that chromium picolinate promotes weight or fat loss. That assessment hasn’t meaningfully changed.
Green tea extract, garcinia cambogia, and conjugated linoleic acid appear frequently in weight loss supplements. None have demonstrated clinically significant weight loss in well-designed human trials. Any effect, if it exists, amounts to a pound or two at most.
Protein’s Role in Weight Loss
Protein isn’t a weight loss drug, but increasing your protein intake is one of the most evidence-backed dietary strategies for losing fat while preserving muscle. High-protein diets increase satiety (you feel full longer after eating) and have a higher thermic effect, meaning your body burns more calories digesting protein than it does digesting carbohydrates or fat.
Whey protein supplementation in particular has been studied extensively. It generally supports maintaining or modestly improving lean muscle mass during weight loss, but this benefit is strongest when paired with resistance exercise. Without physical activity, the effects are much less consistent. Study doses typically range from 20 to 50 grams per day. The practical takeaway: adding a protein supplement can help, but it works best as part of a broader plan that includes strength training, not as a standalone solution.
What Actually Moves the Needle
If you’re looking for the most effective option and you meet the BMI criteria, prescription GLP-1 medications produce weight loss that nothing else comes close to matching. The tradeoffs are cost (often $1,000 or more per month without insurance), injectable delivery, and significant gastrointestinal side effects for many users. Older prescription pills offer a middle ground with more modest results.
Over-the-counter orlistat and dietary supplements sit at the other end of the spectrum. They’re easier to access but produce small effects that are unlikely to be transformative on their own. No supplement has been shown to produce the 5% or greater body weight reduction that medical guidelines consider clinically meaningful.
The most honest answer to “what can I take to lose weight” is that medications can help substantially, but they work best layered on top of changes in how you eat and move. Protein intake, resistance training, and consistent calorie management form the foundation. Medications, when appropriate, amplify those efforts.