The most effective things you can take for weight loss are prescription medications, which now routinely produce 15% to 25% body weight loss in clinical trials. Over-the-counter options exist too, though they deliver far more modest results. What makes sense for you depends on your starting weight, your health profile, and whether you qualify for a prescription. Here’s what the evidence actually supports.
Prescription Injectables: The Most Effective Option
A class of drugs originally developed for diabetes has transformed weight loss treatment. These medications mimic a gut hormone called GLP-1 that your body naturally produces after eating. They work on multiple fronts: slowing digestion so food stays in your stomach longer, acting on appetite centers in the brain to reduce hunger and cravings, and improving how your body handles blood sugar. The net effect is that you eat significantly less without the grinding willpower that dieting usually requires.
Semaglutide (sold as Wegovy for weight loss) produced an average of about 15% body weight loss over 68 weeks in its landmark trial, compared to just 2.4% with a placebo. That translates to roughly 30 to 35 pounds for someone starting at 230 pounds. Tirzepatide (sold as Zepbound) goes further by targeting two gut hormones instead of one. In its 72-week trial, the highest dose produced an average of nearly 21% body weight loss, or about 50 pounds for someone starting around 230.
A newer drug called retatrutide, which targets three hormones simultaneously, is still in clinical trials but has shown even more dramatic results. Participants lost an average of 28.7% of their body weight at 68 weeks on the highest dose, roughly 71 pounds from a starting weight of about 249 pounds. It’s expected to complete its remaining trials in 2026.
Weight loss with these drugs typically plateaus around 60 weeks, usually as your body approaches a healthier weight range. One important caveat: stopping the medication leads to significant regain. A meta-analysis in The Lancet found that people regained about 60% of the weight they’d lost within one year of stopping treatment, which is why most doctors consider these long-term prescriptions.
Who Qualifies for Prescription Medications
The FDA generally approves weight loss medications for adults with a BMI of 30 or higher, or a BMI of 27 or higher if you also have at least one weight-related condition like high blood pressure, type 2 diabetes, or high cholesterol. Some medications are also approved for adolescents aged 12 and older who meet specific obesity thresholds. Your doctor can determine your eligibility, and insurance coverage varies widely depending on your plan.
Prescription Pills
Not everyone wants or can use an injectable. Qsymia is an oral prescription option that combines two active ingredients: one that suppresses appetite and another that reduces food cravings. It’s taken as a capsule once daily. The side effects are different from the injectables and can include tingling or numbness in the hands and feet, trouble sleeping, constipation, dry mouth, and a metallic taste. More serious concerns include mood changes, increased heart rate, and problems with concentration or memory.
Orlistat (available both by prescription and in a lower-dose over-the-counter version called Alli) works differently from everything else on this list. Instead of targeting appetite, it blocks your body from absorbing about a third of the fat you eat. The unabsorbed fat passes through your digestive system, which can cause oily stools, gas, and urgent bowel movements, especially if you eat high-fat meals. Weight loss is more modest, typically in the range of 5% to 7% of body weight.
Over-the-Counter Fiber Supplements
If you’re looking for something you can buy without a prescription, fiber supplements have the strongest evidence, though “strongest” is relative here. They won’t produce anything close to what medications deliver.
Glucomannan, a water-soluble fiber derived from konjac root, expands in your stomach and helps you feel full on less food. In a clinical trial testing several fiber formulations alongside a reduced-calorie diet, a blend of glucomannan, psyllium, inulin, and apple fiber was the most effective at reducing body weight and BMI compared to placebo. The study used about 4.3 grams of glucomannan and 7 grams of psyllium daily. Glucomannan alone, at 3 grams per day, also produced meaningful results.
These supplements work best as part of an overall effort to eat less. They’re tools for managing hunger, not standalone weight loss solutions. Most people don’t reach the recommended 30 grams of dietary fiber per day, so adding a fiber supplement can serve double duty: helping with appetite and improving your overall nutrition. Take them with plenty of water, as they absorb liquid and can cause digestive discomfort otherwise.
Caffeine and Green Tea Extract
Caffeine is a mild metabolic stimulant, and green tea extract has been shown to boost 24-hour energy expenditure by about 4% compared to placebo. That study used 270 milligrams of the active compound EGCG daily, split across three meals. A 4% increase in energy expenditure translates to burning roughly 80 extra calories a day for an average person. That’s not nothing, but it adds up slowly: you’d need about six weeks of that daily surplus to lose a single pound, assuming everything else stays equal.
Caffeine from coffee or tea can also blunt appetite temporarily. If you already drink coffee, you’re already getting this benefit. Concentrated green tea extract supplements can cause liver problems in rare cases, so the brewed tea itself is a safer choice if you want to go that route.
Nutrient Gaps to Watch For
Any approach that significantly reduces how much you eat carries the risk of nutrient deficiencies. This is especially relevant for people on GLP-1 medications, who often eat dramatically less than before. After 12 months of treatment, studies have found that 13.6% of users developed vitamin D deficiency, 4% developed anemia from nutritional deficiency, 3.2% became iron deficient, and 2.6% developed B vitamin deficiency. In one smaller study tracking actual food intake, 72% of GLP-1 users consumed less than the recommended amount of calcium, and 64% didn’t get enough iron.
A daily multivitamin is a reasonable safeguard if you’re eating significantly less, whether from medication or dieting. Prioritizing protein and nutrient-dense foods in whatever you do eat becomes more important when your total volume of food drops.
What Actually Moves the Needle
The honest picture is that prescription medications are in a different league from everything available over the counter. GLP-1 drugs produce 15% to 25% body weight loss. Fiber supplements and green tea extract contribute modestly, mainly by helping you eat a little less or burn a few more calories. They’re reasonable additions to a solid diet and exercise plan, but they won’t replace one.
If your BMI qualifies you for prescription treatment and weight is affecting your health, that conversation with a doctor is worth having. If you’re looking for an edge while managing your weight through diet and activity, a fiber supplement like glucomannan before meals and consistent protein intake are the two most practical, evidence-backed steps you can take on your own.