Weight-Loss Supplements: What Physicians Should Know

Patients frequently come to Leslie Golden, MD, with questions about supplements for weight loss.

“I’d say nearly every patient has tried or considered supplements at some point before they get to me — either because of marketing, recommendations from friends, or desperation after other efforts haven’t worked,” said Golden, a family physician and obesity specialist based in Watertown, Wisconsin. “They often ask: ‘Is this safe? Does this actually work? Can I take this with my current medication?’” 

“There’s a real hunger for answers, but unfortunately, there’s a lot more noise than clarity in this space,” Golden said.

Supplements for weight loss include vitamins, minerals, herbs, amino acids, and fibers marketed to help patients drop weight by reducing appetite, strengthening metabolism, and increasing fat burn.

Such supplements are popular and easy to access, particularly over the internet. The Council for Responsible Nutrition reported that 75% of Americans used dietary supplements in 2024, including products marketed for weight loss.

Studies, however, show conflicting results about whether the products actually work.

A 2022 analysis in the journal Nutrients, for example, reviewed several ingredients commonly used in dietary supplements for weight management: Caffeine, green tea extract, green coffee bean extract, choline, glucomannan, and capsaicinoids and capsinoids.

Researchers found that supplements containing these ingredients “may provide some benefit for weight management and related measures of metabolic health and are generally safe when used in accordance with the manufacturers’ directions.”

Another study published in the journal Obesity, however, found that dietary supplements and alternative therapies for weight loss have a limited high-quality evidence base of efficacy.

In the analysis, researchers reviewed 315 clinical trials of weight-loss supplements and therapies. Authors concluded that many of the studies were not well-designed, were too short, or showed evidence of bias. More randomized, double-blinded controlled trials are needed to demonstrate the efficacy of supplements purported for weight loss, lead study author John Batsis, MD, wrote in the study.

In addition to mixed efficacy outcomes, obesity specialists say there’s serious concerns about the safety, quality control, and transparency of weight-loss supplements.

“There’s an explosion of companies selling hope in a bottle, often without strong science — or any science — behind it,” said Golden, founder of Weight In Gold, a clinic specializing in sustained weight health using health coaching and the latest medications. “These products aren’t regulated like medications, so what’s on the label isn’t always what’s in the bottle. The marketing often plays into shame and unrealistic promises, which can be harmful for people already struggling with weight and self-worth.”

What Should You Tell Patients About Weight-Loss Supplements?

A key message to convey to patients is that weight-loss supplements are not tested for safety or efficacy like medications are, said Beverly Tchang, MD, an endocrinologist and associate professor of clinical medicine at Weill Cornell Medical College, New York City.

The FDA does not approve supplements for safety or effectiveness, nor does it approve their labeling before they’re sold. Under the Federal Food, Drug, and Cosmetic Act, it’s the responsibility of supplement companies to ensure products meet safety standards and adhere to the law.

“I tell my patients that supplements are not tested for efficacy or safety prior to market availability, which means the supplement you take could be as benign as an empty capsule, or it could have toxins,” Tchang said.

Patients should understand the possible harm that can come from weight-loss supplements and the potentially misleading claims of advertisers, said Sarah Bodin, MD, an anesthesiologist, obesity medicine physician, and president of Quality of Life Physician Weight Management, which provides telehealth services to patients in Florida.

“There are many supplements on the market, completely unproved, that claim to be ‘nature’s GLP-1,’” she said. “Additionally, there are a number of substances on the market not only lacking efficacy but that have known adverse side effects.”

Possible adverse effects from weight-loss supplements can include liver damage; cardiovascular side effects like increased blood pressure, heart rate, and abnormal cardiac rhythms; and gastrointestinal side effects, said Bodin.

Some ingredients and additives used in weight-loss supplements have been considered “potentially unsafe” by the FDA, such as geranium or pelargonium graveolens extracts, ephedra, bitter orange, dinitrophenol, and phenylpropanolamine, according to Bodin.

Sibutramine, a weight-loss agent withdrawn from the US market because of safety risks, is still hidden in some weight-loss supplements, said Bodin.

Hydroxycut, a dietary supplement that’s been linked to cases of liver damage, is also still on the market and easily obtainable online.

“No supplement has sufficient human data to confirm clinically meaningful, consistent, long-term weight loss and improved health outcomes,” Bodin said. “This truth underlies what I tell my patients: ‘At best, you are throwing your money away, and at worst, you may harm yourself. If you are seeing a healthcare provider who is selling a non-FDA approved supplement, they are profiting without a likely good outcome.’”

A 2022 commentary in the American Medical Association Journal of Ethics concluded that clinicians cannot ethically recommend weight-loss supplements to patients because “the products’ safety and efficacy are unknown, ingredient lists might not be complete, and advertising could be misleading.”

A practice statement from the Obesity Medicine Association, meanwhile, recommends that clinicians advise patients of the limited evidence supporting the efficacy and safety of many supplements and the lack of oversight by government agencies regarding the claims made about such supplements.

Recommendations and Alternative Avenues to Supplements

Golden said in specific contexts, there are a few supplements she might consider recommending to patients, as long as they understand they’re not “magic solutions.” This could be fiber supplements, for instance, or certain types of protein supplementation, but only when they are part of a larger, comprehensive treatment plan, she said.

“If we’re going to use a supplement, I want to know the brand, the sourcing, and the evidence,” Golden said. “If we wouldn’t prescribe a medication without knowing what’s in it, why would we treat supplements any differently?”

When patients ask Holly Lofton, MD, about weight-loss supplements they can purchase on their own, Lofton researches the supplement in question and looks for scientific articles to determine if efficacy has been documented, she said.

“Most of the time, there is not significant weight loss [from the supplement], which I define as more than 5% weight loss in a clinical trial, so I generally do not recommend supplements for weight loss,” said Lofton, an obesity medicine physician and clinical associate professor of surgery and medicine at NYU Langone Health in New York City.

Instead, Lofton recommends that the implementation of a behavioral management program for weight loss involves nutrition and activity and the potential use of an FDA-approved medications as an adjunct, if beneficial.

For example, Lofton may suggest that patients work closely with a professional trained in nutrition to develop a personalized plan that meets their caloric needs, as well as a formalized exercise routine.

This can be done with the nutritionist and a trainer, or patients can design their own using software or artificial intelligence and YouTube videos, Lofton noted. For long-term weight loss, however, it’s generally recommended to have a 500 calorie per day deficit and to exercise at least 150 minutes per week.

“For weight maintenance, the recommendation is to exercise 240 minutes per week to optimize muscle mass and prevent weight regain,” she said. “Behavioral management means treating habits, such as drinking fluids and being proactive about eating when you feel hunger but not due to emotional events or convenience. It also involves planning meals and including physical activity in the daily routine.”