No supplement will make you lose weight on its own. A handful of supplements have modest evidence behind them, but the effects are small, typically less than a kilogram over several months, and they only show results alongside a calorie-controlled diet and regular movement. Here’s what the research actually shows for the most commonly searched options, so you can decide whether any of them are worth your money.
Green Tea Extract
Green tea extract is one of the most studied weight loss supplements, and the results are real but underwhelming. A dose-response meta-analysis published in the British Journal of Nutrition, pooling data from multiple randomized controlled trials, found that green tea extract supplementation led to an average weight loss of 0.64 kg (about 1.4 pounds) more than placebo. Doses in the studies ranged from 60 to 3,000 mg per day.
Interestingly, the benefit showed up in studies lasting 12 weeks or less. In longer studies, the effects on waist circumference and body fat percentage were no longer statistically significant. That suggests green tea extract might offer a short-term metabolic nudge rather than a lasting fat-burning effect. The active compound works by slightly increasing the rate at which your body burns calories and oxidizes fat, especially during exercise. If you drink several cups of green tea daily, you’re already getting some of this effect without a pill.
Protein Supplements
Whey protein isn’t marketed as a “weight loss supplement,” but it has stronger evidence for appetite control than most products that are. In a study of obese subjects, whey protein significantly raised levels of two key fullness hormones, GLP-1 and PYY, compared to a carbohydrate drink. GLP-1 levels were higher at both 60 and 120 minutes after consumption, while PYY was significantly elevated at 60 minutes. These are the same hormones targeted by newer prescription weight loss medications.
The practical upside: protein takes more energy to digest than carbs or fat (a process called the thermic effect of food), and it keeps you feeling full longer. If you’re not hitting adequate protein through meals alone, a whey protein shake before or between meals can reduce how much you eat later in the day. This isn’t a magic effect. It’s just biology working in your favor, one fewer snack at a time.
Probiotics
Your gut bacteria influence how you store fat, regulate blood sugar, and respond to hunger signals. A systematic review and meta-analysis of randomized controlled trials found that probiotic food consumption led to significant reductions in BMI, visceral fat area, subcutaneous fat area, body fat mass, fat percentage, and waist circumference compared to control groups.
Not all probiotic strains are equal here. Subgroup analyses identified one strain in particular, Lactobacillus gasseri SBT2055, as showing the most promising results. The benefits were also stronger when the intervention lasted at least 12 weeks, suggesting consistency matters more than potency. You can get this strain through certain fermented dairy products or targeted supplements. Keep in mind that probiotic research in weight loss is still developing, and individual responses vary widely depending on your existing gut microbiome.
Berberine
Berberine, a compound found in several plants, gained viral attention online as “nature’s Ozempic.” That’s a massive overstatement, but there is some clinical evidence behind it. A 2022 review of 18 studies found significant decreases in both body weight and BMI in people taking berberine, according to the National Center for Complementary and Integrative Health. The effects were primarily seen at doses above 1 gram per day taken for more than 8 weeks.
The catch: many of those studies had a high risk of bias, and the results across individual trials were inconsistent. Some people lost meaningful weight, others didn’t. Berberine works partly by improving how your body handles blood sugar and insulin, which can reduce fat storage over time. It can also cause digestive side effects like cramping, diarrhea, and nausea, particularly at higher doses. If you’re taking any medications for blood sugar or blood pressure, berberine can interact with them in ways that matter.
Conjugated Linoleic Acid (CLA)
CLA is a fatty acid found naturally in meat and dairy, sold in concentrated supplement form for fat loss. A meta-analysis of 49 effect sizes in the British Journal of Nutrition found that CLA supplementation reduced fat mass by an average of 0.46 kg (about 1 pound) compared to placebo. That’s a real but very small effect.
There’s also a safety concern worth knowing about. Research has linked one specific form of CLA (the trans-10, cis-12 isomer, which is the type found in most supplements) to worsened insulin sensitivity in obese men. Two studies found it caused insulin resistance and elevated proinsulin levels, both of which move your metabolism in the wrong direction if you’re trying to lose weight and improve your health long term. For most people, the modest fat loss doesn’t justify the potential metabolic trade-off.
What to Watch Out For
The supplement industry is loosely regulated, and weight loss products are where the most dangerous ingredients tend to hide. The FDA has banned dietary supplements containing ephedrine alkaloids since 2004 due to serious cardiovascular risks, including heart attack and stroke. More recently, the agency has issued safety warnings about DMAA (a stimulant found in some “fat burners”) and SARMs, which are sometimes sold as body-recomposition supplements but are unapproved drugs with liver and heart risks. These ingredients still show up in products sold online, often under creative names on the label.
A good rule: if a supplement promises rapid or dramatic weight loss, it either doesn’t work or contains something that shouldn’t be in it. Stick to products from brands that use third-party testing, and look for certifications like NSF or USP on the label. These verify that what’s listed on the bottle is actually what’s inside.
Putting It in Perspective
The best-studied supplements on this list, green tea extract and CLA, produce losses of roughly 0.5 to 0.7 kg over the course of a trial. For context, a daily calorie deficit of 500 calories typically produces about 0.5 kg of loss per week. That means the entire benefit of these supplements over several months is roughly equal to one week of moderate dietary changes.
Where supplements can genuinely help is at the margins. Whey protein making you less hungry between meals, a probiotic supporting better gut health, or green tea extract giving you a slight edge during workouts. These are nudges, not solutions. If your diet and activity level aren’t creating a calorie deficit, no supplement will create one for you. Start with the fundamentals, and treat supplements as optional fine-tuning once the basics are locked in.