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4 Best Weight Loss Pills and Diet Supplements of 2020: Reviewed by the Experts

Looking to lose weight fast? Experts recommend the top pills and supplements to buy that are actually effective.

If sustainable weight loss is on your to-do list in 2020, look no further. Our experts have identified the very best weight loss pills and diet supplements to help you assist or jumpstart your weight loss journey this year.

How do weight loss pills work?

Weight loss pills work in a variety of different ways.

  • They block your body's absorption of calorie-containing macronutrients. Some weight loss pills, like orlistat, block the absorption of fat or carbohydrates. This keeps your body from transforming these calories into body fat.
  • They curb your appetite. By regulating your hunger hormones, weight loss pills can keep you from consuming excess calories.
  • They increase your metabolism. Other diet supplements speed up the metabolism, which helps you burn calories more efficiently.

For Paul Claybrook, MBA, MS, CN, Certified Nutritionist at SuperDuperNutrition, the most effective ones contain a variety of ingredients that work in different ways. With this in mind, here are our experts' favorite weight loss pills.

The best weight loss pills and diet supplements

1. Hydroxycut

Claybrook recommends Hydroxycut. Since its 2013 reformulation, Hydroxycut contains a variety of ingredients to aid in weight loss, including appetite-suppressing lady's mantle extract and metabolism-boosting green coffee bean extract and one of our experts' top weight loss supplement ingredients: caffeine.

According to Forrest Przybysz, MBA and founder of Nootropics Resource, caffeine is "a natural, and popular, mental and physical performance enhancer."

"Caffeine is present almost all weight loss pills and is an excellent ingredient in any weight loss supplement as long as the dosages are safe," continues Przybysz.

Today, Hydroxycut remains one of the best-selling weight loss supplements in the U.S.

2. Alli

Claybrook also recommends over-the-counter Alli, whose active ingredient orlistat is a natural inhibitor of pancreatic lipases. In essence, explains Robert Thomas, MSc, RD and Co-Founder of Sextopedia, drugs containing orlistat—like Alli but also prescription Xenical—work by preventing your body from absorbing calories from fat and converting them to body fat.

Studies have shown that Alli can help increase weight loss and reduce blood pressure, though Alli and orlistat-containing drugs have also been linked with gastrointestinal side effects including oily, loose stools. Patients can reduce side effects by reducing their intake of fatty foods while taking Alli.

3. Glucomannan

Claybrook also recommends glucomannan supplements for weight loss, which are produced by a number of brands including Now Foods and Nature's Way. Water-soluble fiber glucomannan is extracted from the konjac yam; when taken in supplement form, it expands in the stomach, increasing feelings of fullness and keeping you from consuming more food than you need. One 2013 study was unable to conclusively prove glucomannan's efficacy as a weight loss supplement, but it did show it was well-tolerated by study subjects.

4. Green Tea Extract

Weight loss supplements containing green tea extract have been shown to boost weight loss thanks in large part to the presence of L-Theanine, a naturally occurring amino acid.

Registered Dietitian Shawn Wells, MPH, LDN, RD notes that green tea extract and theacrine, an alkaline found in Chinese tea, both promote thermogenesis and increase metabolic rate and energy expenditure, which, in turn, promotes weight loss – "similar to caffeine, but with fewer side effects."

"In the term caloric equation of 'energy in' vs 'energy out', they allow for more energy to be expended," he continues, "helping you achieve a caloric deficit a lot easier than having to exercise or severely restrict food intake."

Dr. NavNirat Nibber, ND and Medical Advisor at Advanced Orthomolecular Research, notes that the flavonoids from green tea—but also saffron and quercetin—can help speed up the metabolism by improving liver function. She also notes that they are known to support cellular metabolism and thus weight management. She recommends other hormone support supplements like cinnamon and chromium, which has been shown to help the body balance blood sugar, in tandem with this extract.

Dangers of weight loss pills and diet supplements

When it comes to weight loss, there is no one-size-fits-all solution. Claybrook notes that not all supplements work well for all people.

"For example," explains Claybrook, "caffeine is a bad choice if you already drink lots of coffee. Chromium probably won't help much if your body already balances blood sugar well."

Some pills aren't just ineffective; they could be dangerous and do more harm than good. These include ephedrine, which has been banned for over-the-counter use in the U.S. since 2004 due to the amphetamine-like effects of the supplement. Nibber also cautions against spasmodic "weight loss" teas, which work by causing spasms along the GI tract but can actually lead to insufficient nutrient absorption.

"This can result in conditions such as small intestinal bacterial overgrowth (SIBO)," she says, "which would exacerbate any weight fluctuations or hormone and immune dysfunctions."

Diet pills and supplements you should skip:

  • Phentermine, which can have negative effects for those with high blood pressure or heart issues
  • Fenproporex, a stimulant that may cause heart arrhythmia and even sudden death. It is not approved for use in the U.S.
  • Synephrine/bitter orange, which has been linked to symptoms ranging from headaches and high blood pressure to heart attack and stroke.

Whichever weight loss pills you choose, our experts agree that no pill will work on its own. "Any diet supplement is just that, a supplement," says Claybrook. "It will help you reach your goals, but its effects are not great enough to somehow cancel poor eating habits or lack of exercise."

Emily Monaco
Emily Monaco is a food and culture writer based in Paris. Read more about Emily