The first global review of complementary drugs (herbal and dietary supplements) for weight loss in 16 years – combining 121 randomized, placebo-controlled studies with nearly 10,000 adults – suggests that, based on current knowledge, their use cannot be justified.
Findings from two studies presented at the European Obesity Congress (ECO), held online this year, suggest that some herbal and dietary supplements, while statistically higher in weight loss than placebo, are not enough to keep you healthy and the authors call for more research into their long-term safety.
Over-the-counter herbal and dietary supplements advertised for weight loss are growing in popularity. However, unlike pharmaceuticals, clinical evidence of their safety and effectiveness is not required before they can be placed on the market. Our rigorous evaluation of the best evidence available has concluded that there is not enough evidence to recommend these weight loss supplements. While most dietary supplements appear safe for short-term consumption, they will not produce weight loss that is clinically meaningful. “
Erica Bessel, Lead Author, University of Sydney, Australia
The authors report on herbal supplements that contain a whole plant or combinations of plants as an active ingredient, and on dietary supplements that contain naturally occurring isolated compounds from plant and animal products such as fibers, fats, proteins and antioxidants. They can be bought as pills, powders, and liquids.
Between 1996 and 2006, 1,000 weight loss supplements listed on the Australian Register of Therapeutic Goods were not tested for effectiveness. Supplements can be sold and marketed to the public, with sponsors (who import, export, or manufacture goods) being required, but not required, to provide evidence to support their claims. Only 20% of new listings are reviewed annually to ensure they are in line with requirements. In some countries the only requirement is that dietary supplements contain acceptable amounts of non-medicinal products.
It is estimated that 15% of Americans trying to lose weight tried a weight loss supplement in 2020, a $ 41 billion global industry. Despite their increasing popularity, dietary supplements have been 16 years since the last review of the scientific literature on all available herbal and herbal products.
Herbal medicines that are not effective for weight loss
To provide more evidence, Australian researchers conducted a systematic review of all randomized trials comparing the effects of herbal supplements with placebo on weight loss through August 2018. The data were analyzed for 54 studies that included 4,331 healthy overweight or obese adults aged 16 and over. Weight loss of at least 2.5 kg was considered clinically meaningful. They also rated the study design, reporting, and clinical value.
Herbal additives included in the analysis were: green tea; Garcinia Cambogia and Mangosteen (tropical fruits); white kidney bean; Ephedra (a stimulant that increases metabolism); African Mango; Yerba Mate (herbal tea made from the leaves and branches of the Ilex paraguariensis plant); Field grape (often used in Indian traditional medicine); Licorice root; and East Indian Globe Thistle (used in Ayurvedic medicine).
The analysis found that only one active ingredient, the white kidney bean, resulted in statistically but not clinically greater weight loss than placebo (-1.61 kg; 3.5 pounds).
In addition, some combination supplements containing African mango, stone grape, East Indian globe thistle, and mangosteen showed promising results, but were examined in three or fewer studies, often with poor research methodology or reporting, and the results should be interpreted with caution, say.
Dietary supplements do not work for weight loss
A new systematic review through December 2019 also identified 67 randomized trials comparing the effects of supplements containing naturally occurring isolated compounds with placebo for weight loss in 5,194 healthy overweight or obese adults (aged 16 and over).
Dietary supplements included in the analysis were: chitosan (a complex sugar from the hard outer layers of lobsters, crabs, and shrimp that claims to block the absorption of fat or carbohydrates); Glucomannan (a soluble fiber in the roots of elephant yam or konjac that promotes a feeling of fullness); Fructans (a carbohydrate made up of fructose chains) and conjugated linoleic acid (which claims to change body composition by reducing fat content).
The analysis showed that chitosan (-1.84 kg), glucomannan (-1.27 kg) and conjugated linoleic acid (-1.08 kg) resulted in a statistically but not clinically significant weight loss compared to placebo.
Some supplements, including modified cellulose (plant fibers that expand in the stomach to cause a bloated sensation) and blood orange juice extract, have shown promising results, but have only been investigated in one study and need more evidence before they are said to be recommended for weight loss.
“Herbal and dietary supplements seem like quick fixes to weight problems, but people need to be aware of how little we actually know about them,” says Bessell. “Very few high-quality studies have been conducted on some supplements for which there is little long-term efficacy data. In addition, many studies are small, poorly designed, and some do not report the composition of the supplements studied and the growth in the industry The popularity of these products underscores the urgency for larger, more rigorous studies to be conducted to ensure reasonable assurance of their safety and effectiveness in weight loss. “
European Association for the Study of Obesity