Researchers looked at recent studies testing dietary supplements for weight loss and found something important: about 6 out of every 10 studies were paid for by companies in the supplement business. This matters because when a company funds research about its own product, the results might be biased in favor of that product. The study examined 74 different research papers published in 2023 and discovered that 44 of them had commercial funding. More than half of the companies funding these studies actually sell dietary supplements themselves. This raises questions about whether we can trust the results when the people paying for the research have something to gain if the results are positive.

The Quick Take

  • What they studied: How often companies that sell weight loss supplements pay for the scientific studies that test whether those supplements actually work
  • Who participated: 74 published research studies about dietary supplements and weight loss from 2023, written in English
  • Key finding: 59% (44 out of 74) of the studies were funded by companies with financial interests in supplement sales, suggesting potential bias in weight loss supplement research
  • What it means for you: When you read about a weight loss supplement study, check who paid for it. If the company that sells the supplement also paid for the research, be extra skeptical about the results. This doesn’t mean the supplement doesn’t work, but it means the study might be biased toward showing positive results.

The Research Details

Researchers conducted what’s called a ‘rapid review,’ which is a faster version of a thorough research review. They searched for all published studies from 2023 that tested dietary supplements for weight loss. They only looked at studies written in English and that were randomized controlled trials (the gold standard type of study where people are randomly assigned to take either the supplement or a fake pill). For each study they found, they carefully read the full paper to identify who paid for the research. They then sorted the funding sources into categories: companies in the supplement industry, nonprofit organizations, trade associations (groups representing supplement makers), universities, government agencies, or other sources. They also investigated whether nonprofit organizations or trade associations had hidden connections to supplement companies.

This approach is important because it reveals a potential problem with how weight loss supplement research gets done. When the people paying for a study have a financial stake in the results, it can unconsciously influence how the study is designed, what results get reported, and how the findings are interpreted. By looking at who funded these studies, researchers can alert the public to potential bias that might make supplements look better than they actually are.

This study is reliable because it examined actual published research papers and looked at real funding information. However, the researchers noted that some companies didn’t clearly disclose their connections to supplement sales, so the actual number of biased studies might be even higher. The study only looked at papers from 2023, so it’s a snapshot of one year rather than a long-term trend. The researchers were transparent about what they found and acknowledged limitations in their data.

What the Results Show

Out of 74 studies examined, 44 (59%) reported that their research was funded by commercial sources. These 44 studies involved 64 different companies and 118 separate instances of commercial funding (meaning some studies had multiple commercial funders). More than half of these commercial funders either directly sold dietary supplements or owned companies that did. The researchers found that some companies tried to hide their connections to supplement sales, making it harder to spot the bias. Importantly, none of the nonprofit organizations funding studies had ties to supplement sales, suggesting they may be more independent sources of funding.

The study revealed that commercial funding in supplement research is extremely common. Trade associations (groups that represent supplement makers) and some nonprofit organizations also had financial interests in supplement sales, though the details weren’t always transparent. The fact that 64 unique companies were involved shows this isn’t just one or two bad actors—it’s a widespread pattern across the supplement industry.

This is the first study to specifically look at how much commercial funding exists in weight loss supplement research. Previous research has shown that commercial funding can bias results in other areas of nutrition science, so this finding aligns with what experts already suspected about the supplement industry. The high percentage of commercial funding (59%) is consistent with or possibly higher than bias rates found in other nutrition research areas.

The study only looked at papers published in 2023, so we don’t know if this pattern has been consistent over time or if it’s getting worse. The researchers could only examine studies published in English, so they might have missed important research from other countries. Some companies didn’t clearly disclose their financial interests, so the actual bias problem might be even larger than reported. The study shows that commercial funding exists but doesn’t prove that this funding actually changed the study results—that would require additional research.

The Bottom Line

When reading about weight loss supplement studies, always check the funding source listed in the paper. If a supplement company or a company with ties to supplement sales paid for the research, consider the results with healthy skepticism. Look for studies funded by government agencies, universities, or independent nonprofits, which are less likely to be biased. Don’t assume a supplement doesn’t work just because a company funded the research, but do recognize that positive results might be exaggerated. Confidence level: High—this pattern of commercial funding is well-documented.

Anyone considering taking a weight loss supplement should care about this research. People who read health news and want to understand which studies to trust should understand this bias issue. Healthcare providers should be aware of this funding bias when counseling patients about supplements. People with weight loss goals should not assume that all published supplement studies are equally reliable. This is less relevant for people who don’t use dietary supplements or who get their weight loss advice primarily from their doctor.

This isn’t about how long it takes a supplement to work—it’s about how long it takes to get honest research. Real change in this area would require the supplement industry to adopt stricter transparency rules and for independent funding sources to increase. In the short term (weeks to months), you can start checking funding sources on supplement studies you read. In the long term (years), we may see better regulation of supplement research funding.

Want to Apply This Research?

  • Track the funding source of any supplement study you read: log whether it was funded by the company selling the product, an independent source, or unclear. Over time, this helps you see patterns in which studies might be biased.
  • Before trying a new weight loss supplement based on a study you read, use the app to search for independent reviews of that supplement from sources like the National Institutes of Health or academic medical centers. Save these independent sources in your app for future reference.
  • Create a ‘supplement research sources’ list in your app with trusted, independent sources for supplement information (like PubMed, government health agencies, and university medical centers). When you encounter supplement claims, check them against this list before deciding to try a new product.

This research examines funding bias in supplement studies but does not prove that any specific supplement is ineffective or harmful. Always consult with a healthcare provider before starting any new dietary supplement, especially if you have existing health conditions or take medications. This article is for educational purposes and should not replace professional medical advice. The presence of commercial funding doesn’t automatically mean a study is wrong, but it does suggest you should seek out additional independent research before making health decisions based on a single study.