Weight-loss supplements — pills, powders and liquids — are big business. Overweight Americans spend over $2.4 billion a year on over-the-counter (OTC) diet aids, hoping they will be the magic bullet they need. About 15 percent of American adults have tried weight loss supplements at some time in their lives, but, according to an extensive study out of the University of Sydney, they just won’t work.

Australian researchers took a systematic look at 121 randomized placebo-controlled trials done during the last 19 years, involving numerous popular weight-loss supplements and over 10,000 overweight or obese participants, 16 years or older, from around the world. The study’s conclusion, which was thumbs down on all weight-loss supplements, was presented at The European Congress on Obesity held online this year in May.

“Even though most supplements appear safe for short-term consumption, they are not going to provide weight loss that is clinically meaningful.”

“Over-the-counter herbal and dietary supplements promoted for weight loss are increasingly popular, but unlike pharmaceutical drugs, clinical evidence for their safety and effectiveness is not required before they hit the market,” the lead author of the study, Erica Bessell from the University of Sydney, said in a media release.

Among the herbal supplements included in the study’s analysis were garcinia cambogia, white kidney bean, ephedra, African mango, yerba mate, licorice root, East Indian globe thistle and veld grape. Only the white kidney bean offered a statistically, but not clinically greater weight loss (5.5 lbs.), than the placebo.

“Our rigorous assessment of the best available evidence finds that there is insufficient evidence to recommend supplements for weight loss,” Bessell concluded. “Even though most supplements appear safe for short-term consumption, they are not going to provide weight loss that is clinically meaningful.”

One thing there’s no question about is the need for weight control. According to the World Health Organization (WHO), obesity worldwide has nearly tripled since 1975.

There’s no mystery to weight gain, and the recipe for it is simple: When we consume more energy (calories) than we burn, the pounds add up. A pill can’t prevent this cycle, but you can. The Centers for Disease Control (CDC) recommends getting enough sleep, reducing stress and increasing regular physical activity. Their diet plan includes eating more fruits and vegetables — and fewer processed foods — and sticking to a daily walking routine.

For more tips on how to eat better, change your lifestyle and lose weight, visit the United States Department of Agriculture (USDA).