Supplements for Weight Loss

The weight loss supplement market is booming, with annual worldwide sales surpassing $33 billion. Is it money well spent when the effectiveness of many products is questionable? Studies of them are usually small and have conflicting results. Even for supplements that may work, the weight loss often is just a few pounds and only when combined with diet and exercise. It’s easy to think they’re safe because you can buy them over the counter. But supplements can have side effects or negative interactions with common medications. It’s important to talk to your doctor in advance if you’re tempted to try any for yourself. Be informed. Here's what to know.

Berberine is a substance found in goldenseal, barberry, and other plants. It’s been used in both Ayurvedic and Chinese medicine, often for GI issues. It’s known to regulate blood sugar and fat metabolism. Results of studies on its role as a weight loss supplement are mixed. Some people have lost 5% to 7% of their body weight when they also exercised and added more fiber and protein to their diet. A typical dose is a 500-milligram capsule three times a day before meals. Don’t take berberine if you’re pregnant, breastfeeding, under 18, or taking cyclosporine.

Drinking coffee often helps control appetite. The effect is thanks to both caffeine and chlorogenic acid (CGA), an antioxidant with fat- and glucose-lowering properties. Limited research found that green, or unroasted, coffee beans and their extract may be even more effective. For some, taking between 500 and 1,000 milligrams a day of green bean coffee extract with CGA led to a 2- to 5-pound loss. The weight loss happened over two or three months without negative effects. But long-term research into its effectiveness and safety are needed.

Capsaicin is the spicy compound that gives chili peppers their heat. You may even have used it as a topical for pain relief. Studies involving 10 to 36 milligrams a day showed that it can tamp down the hunger hormone ghrelin, make you feel fuller quickly, and even lead to short-term burning of extra calories. While capsaicin appears safe, existing research isn’t strong enough to tell if it can lead to long-term weight loss.

Chitosan is a compound extracted from shellfish shells. It’s known to interfere with the absorption of fats in the GI tract, leading to lower cholesterol and body weight. A small number of studies looked at chitosan for weight loss with dosages between 1 and 4.5 grams a day and for different lengths of time. There was a small mean decrease in BMI of 1.27. In one study, participants lost 5 pounds after six weeks. Chitosan is rated safe by the European Food Safety Authority for up to 3 grams a day.

Conjugated linoleic acid (CLA) is a type of omega-6 fatty acid typically found in dairy and meat products. It has the potential to improve insulin sensitivity and fat metabolism and lower triglycerides and LDL, the "bad" cholesterol. Most studies have been small with mixed results, but one review found that taking 3.4 grams or more daily for at least 12 weeks had the greatest effect — a loss of about 1.3 kg. CLA is generally recognized as safe.

Curcumin is the powerful antioxidant compound in turmeric, the stem of a plant native to southeast Asia. It’s been used as a spice as well as a medicinal for thousands of years. Curcumin helps fight the oxidative stress that plays a role in obesity. It's been linked to better fat metabolism, increased calorie burn, and a healthier gut. Small studies found that 100 milligrams daily of curcumin supplements for eight or more weeks can lower BMI and bodyweight in small amounts. Check with your doctor first if you take antidepressants, blood thinners, antibiotics, antihistamines, statins, or warfarin among others because of drug interactions.

Garcinia, a Southeast Asian evergreen, is the source of hydroxycitric acid. It's touted as an obesity fighter and appetite suppressant. But studies are inconsistent. In one analysis, only two of 15 studies were positive for weight loss (ranging from 3-8 pounds). Another found that durations and dosages (from 400 to 2,400 milligrams a day) were too varied to draw conclusions. In 2009, the FDA urged people to avoid garcinia-based Hydroxycut because of 23 cases of liver toxicity. That risk has also been linked to pure garcinia extracts. Unlabeled substances have been found in some products. It’s not recommended for pregnant women.

Glucomannan is a soluble fiber from the Asian konjac plant. When mixed with water, it creates a gel-like substance. It slows digestion and increases feelings of fullness so you eat less. However, study results are mixed. Two analyses found that 2 to 4 grams per day resulted in some weight loss when people also cut calories. A third analysis found no effect. There were also reports of GI side effects like tummy pain, gas, and diarrhea. Though it might be worth a try — it may lower blood sugar and cholesterol — its value for weight loss is unclear.

Green tea and green tea extract (GTE) are rich in polyphenols, specifically the catechin EGCG that’s linked to higher calorie burning in lab studies. But studies in people haven't been conclusive. In a review of 38 trials on green tea, only two of the 16 deemed high-quality noted a weight loss of about 3 pounds within two months. Reported side effects included nausea, vomiting, diarrhea, abdominal pain and GI bloating. Effects were worse after taking GTE on an empty stomach. Of greater concern, green tea extract can cause liver damage. Consider sipping a cup of caffeinated green tea instead.

It’s been suggested that L-carnitine, an amino acid-like compound found in red meat, fish, poultry, and dairy products, contributes to weight loss. L-carnitine may break down stored fat for energy and make you feel full longer. But clinical trials of supplements are contradictory. Some showed no weight loss, but one review of nine trials showed some. Doses were up to 4 grams a day and were taken for 30 to 360 days. People in the studies lost about 3 pounds more than those who took a placebo, regardless of the study duration or dose. While it holds promise, the best and safest daily dose is unknown. 

You’ve likely heard about the anti-inflammatory benefits of omega-3 fatty acids, nutrients found in fatty fish and some plant-based foods like flaxseed. A study that looked at weight loss and cognitive benefits in 40 adults on a weight loss diet program did find decreases in weight, waist size, and BMI. The people in the study took 1,020 mg of omega-3s for 12 weeks. (It did not demonstrate brain benefits.) But a review of 11 studies evaluating omega-3s as part of a weight loss program found no advantage. Reviewers concluded that more research is needed.

Psyllium is another water-soluble plant fiber that may fill you up, keep you feeling full longer, and help you eat less. But study results on its weight loss effects are not outstanding. One research review found it helped reduce body fat as part of a bigger diet and lifestyle modification plan. Studies lasted six to 12 months. Some people who took 10 or more grams a day did lower their BMI. However, other reviews noted improvements in cholesterol, triglycerides, and blood sugar, but not weight or BMI. While psyllium can keep you regular, its effects on weight loss aren’t conclusive.

Spirulina is a blue-green algae popular as a health supplement because it’s rich in almost all essential amino acids, omega-3 fatty acids, minerals, vitamins, and antioxidants. Animal studies of spirulina extract showed anti-obesity and fat-lowering effects. But a handful of small studies involving people have found limited effects on weight loss. Dosages between 1 and 4.5 grams a day for between six and 12 weeks led to a drop of about 3 pounds with no change in BMI. Though several grams a day are considered safe, it may be most effective for cutting appetite.

Yerba mate is a caffeinated drink that originated in South America. Brewed from leaves of a native tree, it has properties that can rev up metabolism and energy output, especially during exercise. Though limited, some studies have been positive. A small group of people saw decreases in body fat mass after using a daily 3,150 milligrams yerba mate supplement for 12 weeks. Another group with high cholesterol who drank about 4 cups of yerba mate tea daily for eight weeks saw boosts in HDL (good) cholesterol and lower BMI. There are concerns about side effects, including cancer, when consumed as a hot beverage.

A common theme running through most studies of these weight loss supplements is uncertainty about how much to take, for how long, and whether you’ll see meaningful results. Even though they’re sold over the counter or labeled natural, they could still cause side effects. Ask your doctor for guidance. Remember that the FDA does not regulate supplements. The key to losing weight is a lifelong lifestyle approach that involves eating well, taking in fewer calories, and being active on a regular basis. It also helps to set small, achievable weight loss goals that you can build on over time.