Skip to content

15 Worst Supplements For Weight Loss

If you're taking these supplements to lose weight, you're throwing away money.

According to the Office of Dietary Supplements (ODS) at the National Institutes of Health (NIH) Americans spend over $2 billion a year on dietary supplements promoted for weight loss despite the fact that eating healthful foods, cutting calories, and being physically active are all proven ways to get thinner.

And while you might not think twice about taking a dietary supplement in an effort to look your best, it turns out that several ingredients within these supplements that claim to help us shed unwanted pounds don't contribute to weight loss in any way, and may actually be harming our overall health.

For example, though calcium promotes excellent bone health, there's no evidence to suggest that it helps you burn fat or decrease fat absorption. On the contrary, too much calcium has actually been proven to cause constipation and decrease your body's absorption of iron and zinc, which research has shown can play a role in weight loss.

Though carnitine supplements and supplement ingredients such as caffeine and chromium can help put you on a path to toned abs, it's important you know the supplements and ingredients to avoid. Continue reading for over a dozen of the worst supplements for weight loss, according to the NIH, and get slimmer the healthy way by brushing up on the 100 Best Weight Loss Tips Ever!



Beta glucans pill

Beta-glucans are soluble dietary fibers in bacteria, yeasts, fungi, algae, oats, and barley. Though they might slow down the time it takes for food to travel through your digestive system, making you feel fuller, the NIH says beta-glucans (as a supplement) don't have any proven effect on weight loss. If you're looking for whole food sources of fiber that can actually help you look slim and trim, take a look at this list of The 43 Best Foods for Fiber!


Bitter Orange

Orange pill

Bitter orange contains a stimulant called synephrine and claims to burn calories, increase fat breakdown, and decrease appetite. As noted by the NIH, dietary supplements with bitter orange usually also contain caffeine and other ingredients, and bitter orange is in some weight loss dietary supplements that used to contain ephedra—another stimulant-containing herb that was banned from the U.S. market in 2004. Though the NIH says bitter orange might slightly increase the number of calories you burn and reduce your appetite a little, whether it can actually help you lose weight is unknown. Furthermore, the NIH has determined that supplements containing bitter orange might not be safe, because they can cause chest pain, anxiety, headaches, muscle and bone pain, a faster heart rate, and higher blood pressure. In other words, steer clear of supplements boasting bitter orange as an ingredient if you're looking to lose weight.




Though calcium is a mineral your body needs for healthy bones, muscles, nerves, blood vessels, claims that it can help you burn fat and decrease fat absorption are unfounded. Per the NIH, calcium—either from food or in weight-loss dietary supplements—probably doesn't help you lose weight or prevent weight gain. What's more? Too much of the nutrient found in milk and cheese (more than 2,000–2,500 mg a day) can cause constipation and decrease your body's absorption of iron and zinc. Similarly, too much calcium from supplements (but not foods) might increase your risk of kidney stones.



Red pill

Capsaicin is the active ingredient in chili peppers that gives them their bold, hot flavor, and although some studies have shown that this substance can stimulate weight loss because it helps burn fat and calories while keeping you satiated, the NIH notes it hasn't been studied enough to know if it will help you lose weight. Too much capsaicin, the organization says, can cause stomach pain, burning sensations, nausea, and bloating.



Shrimp shells

Chitosan is a compound that comes from the shells of crabs, shrimp, and lobsters and is said to bind fat in the digestive tract so that your body can't absorb it, but the NIH has found the substance binds only a tiny amount of fat—not enough to help you lose much weight. Though chitosan seems to be safe, it can cause flatulence, bloating, mild nausea, constipation, indigestion, and heartburn, and is not recommended for people with a shellfish allergy.




Forskolin is made from the roots of a plant called coleus forskohlii that grows in India, Thailand, and other subtropical areas. Though some claim it helps you lose weight by decreasing your appetite and increasing the breakdown of fat in your body, the NIH says more research needs to be done in order confirm those assertions. Currently, the organization says forskolin doesn't seem to have any effect on body weight or appetite and can cause frequent bowel movements and loose stools.



Brown seaweed

Fucoxanthin comes from brown seaweed and other algae, and supposedly stimulates weight loss by burning calories and decreasing fat. However, according to the NIH, only one study concerning fucoxanthin included people. Therefore, the organization says more research must be done before determining if the substance contributes to weight loss.


Garcinia Cambogia

Garcinia cambogia

Garcinia cambogia is a tree that grows throughout Asia, Africa, and the Polynesian islands. Hydroxycitric acid in the tree's fruit is claimed to decrease the number of new fat cells your body makes, suppress your appetite and thus reduce the amount of food you eat, and limit the amount of weight you gain, but the NIH has determined garcinia cambogia has little to no effect on weight loss. Furthermore, consumption of garcinia cambogia can cause headaches, nausea, and symptoms in the upper respiratory tract, stomach, and intestines.




Glucomannan is a soluble dietary fiber from the root of the konjac plant that some say absorbs water in the gut to help you feel full. While the NIH says there is no evidence glucomannan aids weight loss, the nutrient might help lower total cholesterol, LDL ("bad") cholesterol, triglycerides, and blood sugar levels.


Guar Gum

Guar gum

Guar gum is a soluble dietary fiber in some dietary supplements and food products. Though it's claimed to make you feel full, lower your appetite, and decrease the amount of food you eat, the NIH says this probably doesn't help you lose weight. Furthermore, the organization notes that if guar gum isn't taken with enough fluid it can cause abdominal pain, flatulence, diarrhea, nausea, and cramps.




Hoodia is a plant from southern Africa that is used as an appetite suppressant in that part of the world. According to the NIH, though, the plant probably won't help you eat less or lose weight. In fact, analyses showed that some "hoodia" supplements sold in the past contained very little hoodia or none at all. To make matters worse, the NIH also questions the safety of hoodia, noting it can cause rapid heart rate, increased blood pressure, headaches, dizziness, nausea, and vomiting. In short, steer clear.



Probiotic pill supplement

Probiotics are microorganisms in foods, such as yogurt, that help maintain or restore beneficial bacteria in your digestive tract. Though studies have shown they promote good gut health, the NIH determined probiotic supplements seem to have "little to no effect on weight loss," but included the caveat that they "haven't been well studied."


Raspberry Ketone


Raspberry ketone, which is found in red raspberries, is said to be a "fat burner," though it has only been studied as a weight-loss aid in combination with other ingredients and not on its own. For that reason, raspberry ketone's effects on body weight are unknown, as are any harmful side effects it might cause.


Vitamin D


Your body needs vitamin D for good health and strong bones, but can it help stimulate weight loss? Though people who are obese tend to have lower levels of vitamin D, the NIH has determined there is no known reason why taking vitamin D would help people lose weight. Furthermore, while vitamin D from foods and dietary supplements is safe at the recommended amounts of 600‒800 IU a day for adults, an excess of vitamin D (more than 4,000 IU a day) can be toxic and cause nausea, vomiting, poor appetite, constipation, weakness, and irregular heartbeat.




Yohimbe is a West African tree, and yohimbe extract is an ingredient in supplements used to improve libido, increase muscle mass, and treat male sexual dysfunction. It is also found in some weight-loss supplements and is claimed to increase weight loss, though the NIH determined the extract doesn't help you shed any pounds.

In fact, the organization also questions the safety of the substance, noting that at doses of 20 mg or higher it can have severe side effects. According to available information, yohimbe can cause headaches, high blood pressure, anxiety, agitation, rapid heartbeat, heart attack, heart failure, and even death, which is likely why the NIH strongly recommends you consult a healthcare provider before taking it or anything containing it. For healthy and safe ways to drop some unwanted pounds, take a look at 50 Ways to Shrink Your Belly!