13 Weight-Loss Products Nutritionists Never Buy—and Neither Should You

Updated: Oct. 18, 2018

These trendy items are everywhere on social media and in magazines but do they work? Spoiler alert: There is no magic pill that "blocks carbs," "doubles metabolism," or helps you "lose weight while you sleep."

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Raspberry ketones

One of the hottest supplements on the market right now, raspberry ketones claim to help put your body in “ketosis” and burn fat faster. Some even claim to “block” absorption of carbs. This is all bogus and shows a misunderstanding of the science, says Scarlett Full, registered dietitian at Growing Naturals. One study found the synthetic ketones provided some protection against weight gain and fatty liver disease… in mice. Moreover, they didn’t help the rodents lose weight or fat, she explains, adding that the dosage in the study was incredibly high, much higher than what anyone would get with a supplement. “There is zero current evidence that raspberry ketones work for weight loss in humans,” she says. Want the real scoop on effective weight loss? Check out these 37 weight-loss secrets nutritionists won’t tell you for free.

Juice Kits

Juice kits

While juice diets have been around forever, prepackaged juice kits have really taken off recently—and that’s a huge problem for consumers, Full says. These kits provide a series of bottled juices that you are supposed to drink in place of all food for three to seven days; they promise rapid weight loss and “detox” effects. “While you may lose weight from cutting your calories so drastically, you can pretty much count on regaining all the weight, and probably more, shortly thereafter,” she says. In addition, while the juices themselves may be derived from healthy fruits and vegetables, the juicing process strips out nutrients and the diet is lacking in fat, protein, and fiber, she adds. Want to know the right way to lose weight? Check out these healthy-eating secrets from 17 top nutritionists.

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Garcinia cambogia

Garcinia cambogia is a trendy supplement made from a tropical plant that’s similar to a pumpkin. The capsules supposedly block fat and suppress your appetite but these claims are patently false, says Armen Ghazarians, nutritionist and CEO of Finish Fit. “One study compared garcinia against a placebo pill. There was absolutely no difference in weight or body fat percentage between the two groups at the end of the study,” he explains. Even more concerning, a separate study found it to be associated with liver toxicity. Even if the plant did have some weight loss benefits, supplements, in general, are unregulated; in other words, there’s no way to be sure of the strength of the pills—or whether they’re full of sawdust or cornstarch, two common fillers listed on the labels.

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Forskolin is an herb that people claim can do things such as boost your metabolism. fix your thyroid, and increase your sex drive. But does it work? The science suggests not, says Ghazarians. One study, published in the Journal of the International Society of Sports Nutrition that involved 23 overweight women, found no weight loss effects at all. Things get even more complicated by the fact that forskolin is often included in weight-loss “blends” with many other herbs and ingredients, all of which make it hard to tell if anything is working, he adds. It’s not only weight-loss products you need to be wary of—here are 15 vitamins nutritionists won’t take and neither should you.

Blue And White Vitamin Capsules
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These drugs have long been popular among bodybuilders and athletes in sports that have to “make” a certain weight, like boxers and wrestlers. But while they do help you drop pounds fast, it’s not real weight loss you’re seeing, Full says. “Diuretics were never intended for weight loss; their purpose is to help the body excrete excess water and salt,” she explains. “Any weight you lose would be purely from water.” Worse, if you take more than the recommended dose it can lead to dangerous side effects such as dehydration, dizziness, muscle cramps, weakness, confusion, heart palpitations, increased blood sugar, nausea, she adds.

Diet coke
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Diet soda

Many dieters find solace in a diet Coke or other beverage made with zero-calorie sweeteners. You can have your sweet treat sans guilt, so what’s not to love? A lot, actually, says Angela Bicos Mavridis, Holistic Nutritionist and CEO and founder of TRIBALÍ Foods. The problem is the artificial sweeteners. “Even though they don’t have calories or raise your blood sugar, they irritate your gut lining, which is counterproductive to health and often can sabotage your weight loss goals,” she says. A recent study, published in Nature, even found that artificial sweeteners are toxic to good gut microbes, and they significantly increase insulin resistance, a precursor to diabetes. These are one of the 15 ingredients nutritionists never cook with.

Meal replacement bars

Meal replacement bars

Deciding what to eat is one of the hardest parts of being on a diet—which is why the idea of having a meal in a bar is really appealing. Unfortunately, the convenience removes a lot of the nutrition, Mavridis says. While many meal replacement bars and shakes are low in calories, many have too much sugar and are full of artificial ingredients; they can also be missing vital nutrients found in whole foods, she explains. When it comes to losing weight, it’s important to remember that the quality of your food is just as important as the calories, she adds.

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Detox herbal blends

You read “detox” and think you’re getting rid of harmful toxins in your body but what it usually means is “you’ll be spending a lot of time in the bathroom.” Detox pills and drinks these days are often glorified laxatives marketed to desperate dieters looking to lose weight fast with minimal effort. But while they may help you drop a few pounds in the short term (who knew you had three pounds of poop in there?), they have serious, long-term health consequences, warns Josh Axe, DNM, CNS, DC, nutritionist and founder of Ancient Nutrition and DrAxe.com. Even if you ignore the health risks, research studies have found that not only do they not produce significant weight loss but they may even promote long-term weight gain, he adds.


Weight-loss tea

These days, it’s nearly impossible to open any form of social media without seeing some celebrity peddling weight-loss teas that claim to boost your metabolism, detox your body, and slim your waistline. Unfortunately, these products are often pumped full of harmful ingredients like caffeine, laxatives, and diuretics to give you the illusion of quick weight loss, Dr. Axe says. Even if they do help a little, the results will be short-lived; studies have found that dieters develop a tolerance to these ingredients over time, he adds. Perhaps the worst part is that these teas are unregulated: In independent tests of the teas, investigators have found that many don’t contain the ingredients on the label—and some have toxic ingredients like heavy metals.

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Appetite suppressants

Anything labeled as an “appetite suppressant” should be off-limits, says Amanda Capriglione, a registered dietitian and owner of Food Balance Inc. in New York. “You have an appetite for a reason—it’s a natural biological response, not something to be suppressed,” she says. “It’s your body’s way of telling you that it needs fuel to carry out its daily functions like breathing and producing hormones; all of those processes need energy—food, in other words.” Rather than trying to banish your hunger cues, look at food as fuel and decide what nutrition your body is really hungry for, she says. Instead, try one of these 12 weight-loss tricks nutritionists swear by.

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Fat burners

There are many weight-loss supplements marketed as “fat burners”; many claim you can lose weight literally while you sleep. This is not only ridiculous but potentially life-threatening, says Laura Burak, a registered dietitian in New York. “Many of these products contain ingredients that unnaturally speed up your heart rate and possibly interact with other medications or supplements you are taking,” she says. Some fat burners have even been linked to heart attacks. “Ignore the marketing, a magic weight loss pill just does not exist,” she adds.

Bottled smoothies
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Bottled fruit smoothies

Soda is a known diet buster. As an alternative, many people turn to juice-sweetened beverages like bottled smoothies. Unfortunately, these drinks are still packed with sugar and loads of empty calories, says Ashley Reaver, a registered dietitian at My Weekly Eats. “It is clear from the research that consumption of sweetened beverages makes the body crave more sweets,” she explains. “Even low-cal ‘diet’ drinks cause subsequent cravings for sweet foods later in the day.”

Frozen meals
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Frozen diet meals

They may be convenient, but frozen low-calorie meals such as Healthy Choice, Weight Watchers, Lean Cuisine, and the rest are typically loaded with preservatives and chemicals while falling short on real nutrients, Reaver says. Often they’re just too low in calories, as well, she adds. Reaver also dislikes the fact that they prevent you from learning how to plan, shop, and prepare healthy food for yourself; these are the skills you’ll need if you want to keep the weight off long term, she says. Now check out these 42 fast and easy tips for shedding pounds.