The Fit gummies look like standard marijuana edibles: orange squares with a sugar coat, sold in packaging that’s a cross between the bright colors of a bag of candy and the sterility of a bottle of pain relievers.

These edibles, however, promise something different: They won’t make you high, but they will help you diet. Or, as the company that makes them puts it, they will “help disrupt unhelpful eating habits and put you back in control of your diet.” But the science behind these new gummies is murky.

Sold by Wana Brands, a well-established edibles company, Fit gummies are available only in Wana’s home state of Colorado (for now). One of the ingredients is tetrahydrocannabivarin, known as THCV, which could be the next big thing in cannabis.

THCV is one of the compounds found in the marijuana plant, but it does not appear to have psychoactive effects. Some studies have shown that THCV may have an effect on appetite and diabetes.

Cannabis has long been associated with “the munchies,” so it is surprising to see a form of it sold as a diet aid. But Fit gummies are less of an anomaly than they may appear to be. As more states have legalized cannabis, companies that sell the drug have developed an increasingly wide range of products, many of which cater to modern society’s desire for self-improvement.

Today, the promises of marijuana marketers are manifold: Cannabis can help with sleep, with libido, with focus or with sociability; it can start the day, end the day or prolong it.

Wana’s marketing materials state that the product’s weight-management benefits are proven by a 2021 clinical trial that was commissioned by its partner on the gummy, ECS Brands, and supported by the National Institutes of Health. According to the Wana’s website, “the recently completed NIH-supported, 90-day human clinical trial found 100 out of 100 participants in the study lost weight without exercise or changing daily caloric output values.”

ECS Brands’ informational sheet on the trial says it was performed under the guidance of the Mayo Clinic.

Both the N.I.H. and the Mayo Clinic said they had no record of the trial, nor is it registered on ClinicalTrials.gov. Arthur Jaffee, the founder and chief executive of ECS Brands, insisted N.I.H. was involved and called the discrepancy a “paperwork issue.” “We have full confidence that everything that we did is accurate and true,” he said.

The results of the trial have not been published in a scientific journal or peer reviewed.

“Despite the lack of randomized controlled trials, considered the ‘gold standard’ for pharmaceuticals, there is very strong consumer demand for cannabis products that tap into the myriad potential benefits the plant can provide,” Mike Hennesy, the vice president of innovation at Wana Brands, wrote in an emailed statement.

In the marijuana industry, “the science is very far behind the marketing and the public consumption,” said Margaret Haney, the director of the Cannabis Research Laboratory and co-director of the Substance Use Research Center at the Columbia University Medical Center. “Companies have taken off with all sorts of claims.”

From Ole Miss to New ‘Bliss’

As the market for marijuana expands — 36 states have legalized medical sales of the drug and 18 have done so for recreational sales — companies are devising new ways to attract customers.

Where once smoking a joint meant forsaking control and performing the psychological equivalent of throwing spaghetti at a wall, today, the experience can be much more measured and, according to many cannabis companies, even targeted.

Dosist, in California, sells products with simple names like “sleep,” “bliss,” “arouse” and “calm.”

The idea, according to Anne-Marie Dacyshyn, the company’s president, is that the Dosist product can help the user “function at an even better level.”

“These are products that help you perform and help you stay active and elevated in your day-to-day routines,” Ms. Dacyshyn said in a Zoom call.

Jason DeLand, the executive chairman of Dosist, said that he sees the company’s peers as other lifestyle and wellness businesses, like Peloton, the exercise equipment company, or Hims and Hers, the tele-health company.

Despite branding language that features words like “control,” “formula” and “precise,” Mr. DeLand makes no pretense at hard science. “I’m not going out there and working with universities and trying to get peer-reviewed science,” he said. “We’re not working in a pharmaceutical research function with the F.D.A.”

Instead, the company collects survey data from users, asking questions like: What did the product taste like? How did you sleep? That consumer feedback becomes one of the factors in how Dosist categorizes products.

The use of cannabis to treat a range of ailments stretches back long before its recent legalization. For thousands of years, people have taken it for conditions like epilepsy, glaucoma, insomnia, nausea and pain, among others.

According to an overview by Marc-Antoine Crocq, who studies the history of psychiatry and psychopharmacology at University of Upper Alsace in Mulhouse, France, mentions of cannabis show up in ancient texts from India, Egypt and the Roman Empire. Dr. Crocq writes that Queen Victoria took cannabis for menstrual cramps, and Empress Sisi of Austria found that it eased her cough.

In recent years, supporters of marijuana legalization have harnessed the drug’s medicinal narrative to further their cause. And its legalization hasn’t been limited to liberal-leaning states; Florida, Arizona and Utah allow sales of medical marijuana.

But despite being widely marketed as a medicine, cannabis has made few inroads with the Food and Drug Administration. Marijuana’s status as a federally illegal drug has made it difficult to test the plant’s medical applications. The F.D.A. has also said that consistency — in quality and in dosing — is a challenge with cannabis.

The cannabis plant is made up of different compounds, including cannabinoids, of which at least 125 have been identified. One of these is tetrahydrocannabinol, or THC, which was discovered in the 1960s and is responsible for the psychoactive effects of marijuana. Another is cannabidiol, or CBD, a wellness industry darling that has been incorporated into food, drinks, dog treats, suppositories and skin care and makeup products.

So far, the F.D.A. has approved only one drug that contains CBD: Epidiolex, a product that treats rare seizure disorders. Naturally occurring THC has no approved use at all.

That hasn’t stopped companies that sell cannabis from promising that their products will reduce anxiety, depression, inflammation, pain and insomnia (and in the case of CBD, all without getting the consumer high). But the research lags the promises.

As a Schedule 1 drug, marijuana is seen by the Drug Enforcement Administration to have a high potential for abuse. The D.E.A. categorizes drugs into five groups “depending upon the drug’s acceptable medical use and the drug’s abuse or dependency potential,” and marijuana is in a higher risk category than oxycodone, fentanyl and Adderall.

To study the drug, researchers have to obtain a Schedule 1 license from the D.E.A.

“There’s a room that I get into with my fingerprint,” Dr. Haney said of where the marijuana she uses in experiments is stored. “When people smoke, I have to save the buds. I can’t let one stray piece of cannabis disappear.”

Another challenge she faces in conducting studies is sourcing. Before changes that came into effect in May, only one place could supply marijuana for federally approved experiments: the University of Mississippi, which is paid by the government to grow and store marijuana.

“It’s not what is being used by the consumer, it’s government-grown cannabis that nobody uses,” said Dr. Ariana Nelson, an associate professor of anesthesiology and pain medicine at the University of California Irvine. “It doesn’t accurately reflect the benefits or detriments of cannabis that’s being used in states where it’s been legalized.”

Dr. Nelson, who works at a state-funded university, said that it would be nearly impossible for her to get a cannabis study approved that wasn’t epidemiological or safety focused because of liability concerns.

“Companies would have to spend so much money to provide the F.D.A. with everything they need,” Dr. Haney said. “They don’t seem to need to do that. They can jump in, say whatever they want and make money hand over fist.”

Despite the lack of evidence of THC’s and CBD’s curative powers, customers have flocked to products containing the cannabinoids. The global cannabis market was valued at $22 billion in 2020, according to Mordor Intelligence, a research firm.

Certainly, some portion of that market is made up of consumers who want to get high for fun. But plenty of customers are also looking to solve medical ailments, sleep better, increase their libido, even out mood swings or manage pain.

Some of them may turn to cannabis because of the prohibitive costs of certain medications, a lack of access to those medications or mistrust of the pharmaceutical industry, said Lucas Richert, a historian of drugs and medicines at the School of Pharmacy at the University of Wisconsin-Madison and the editor of “Cannabis: Global Histories.”

“They want to use what they perceive to be more natural or organic products that don’t emanate from what they perceive to be the pharmaceutical industry or mainstream medicine,” Dr. Richert said.

Though there are studies that show that cannabis can help with certain medical conditions, the science is limited. For example, cannabis is often marketed as an analgesic, with some companies going so far as to claim that it can substitute for opioids. But the drug’s effectiveness in treating pain is uncertain.

“Especially with more potent cannabis, there is evidence that with higher quantities of THC, patients actually experience their pain in a more dysphoric way,” Dr. Nelson said. “There’s a dose-dependent effect. There’s a sweet spot that lessens pain, but the THC can also heighten the experience of pain.”

One day, researchers and doctors hope, the science will catch up to the demand and consumers will be able to purchase cannabis knowing exactly how much to consume and what effect it will have.

“Is there a future in which people will be able to buy cannabis products that target specific needs?” Dr. Nelson said. “Definitely. We would have it already if cannabis were rescheduled. You can quote me on that. I don’t care if the Feds come after me. It’s ridiculous.”

The Research

Wana Brands Fit gummies claim to target a type of receptor in the human body called CB1, which is part of the endocannabinoid system.

The system was discovered in the early 1990s. Receptors in the network are influenced by cannabinoids found both in the body, and outside it (like THC and THCV). Overall, the system is involved in emotional processing, sleep, pain control and eating.

Because the system is a recent discovery, there is still a lot to learn about it. “To what extent the endocannabinoid system can alleviate physical or psychiatric conditions is still really poorly understood,” said Amir Englund, a cannabinoid psychopharmacologist at King’s College London. “If you interfere with the endocannabinoid system, you might interfere with other systems. To what extent, we don’t know and depends on the individual.”

The cannabinoid THCV was discovered by scientists in 1970. “THCV seems to be a neutral antagonist,” said Roger Pertwee, one of the scientists who discovered THCV and the endocannabinoid system, and an emeritus professor at the Institute of Medical Sciences at University of Aberdeen in Scotland. This means that THCV blocks the CB1 receptor and prevents other cannabinoids from binding to it, but it does not switch off the receptor’s own background activity.

Dr. Pertwee said that there is evidence in animal experiments that blocking CB1 could be effective in reducing obesity and reducing appetite.

But there has been little clinical testing of this theory.

“What’s very important, and I’m not sure it’s done well enough, is that there are clinical trials done with any particular product to assess its benefits and its risks, and then you could say whether or not to allow it,” Dr. Pertwee said. “If you do experiments in mice and rats, that’s one thing. But you need to do it with humans.”

This is not the first time a company has attempted to create a weight-management product by acting on the CB1 receptor. Rimonabant, a synthetic drug approved in Europe in 2006, was effective at causing weight loss and controlling blood glucose levels. It also led to side effects that included nausea, upper respiratory tract infections, depression and suicidal ideation and was taken off the market in 2008.

Mr. Hennesy, of Wana Brands, said that Fit gummies do not cause the same side effects as Rimonabant.

Wana and ECS Brands provided The New York Times with a research paper to support their claims. The authors listed on it are Jason Hastings, the chief science officer at ECS Brands, and Alex Buettner, a consultant who specializes in data, technology and statistical analysis. (ECS Brands provided Wana Brands with the cannabinoid concentrate that Wana Brands uses in the Fit gummy.)

ECS Brands said that Melanie Montgomery and a company called Clinical Studies US performed the trial. The N.I.H. has no record of either.

A person named Melonie Montgomery registered the Clinical Studies US website in 2016. The site says that the company has provided “expertise to the Nobel Prize winning team on intracellular hydration.”

The Times tried to reach Ms. Montgomery by phone and by email to verify the information given by ECS. An unsigned email returned by a person identifying themselves as Ms. Montgomery’s assistant said Ms. Montgomery was unavailable and that “we do not work with N.I.H.”

The email also said that Ms. Montgomery “has no affiliation with the Mayo Clinic.” Asked to provide another example of work Clinical Trials US has done, the email’s sender wrote: “We do not own any of the studies that we preform so we do not have the rights to provide them to you.”

The experts interviewed for this article, including cannabis and pharmacology researchers and clinicians, spotted several red flags in the paper. For one, the paper claims that its study was sponsored by the National Institutes of Health, which the N.I.H. denied. The paper makes no mention of ethical oversight and does not appear to have been approved by an institutional review board, a type of group that reviews clinical trials in order to protect human research subjects.

ECS Brands said in a phone call that the study was approved by a review board but would not provide additional details or confirm such information in writing.

Experts also pointed out that the paper does not state where the trial was conducted or how subjects were recruited.

And, they said, the numbers seem too good to be true.

In marketing materials, ECS Brands says that 100 out of 100 participants who took its product lost weight.

“I’ve seen very few studies where anything works 100 percent of the time,” Dr. Englund said.

The ECS Brands marketing material also says that its product led to a 61 percent reduction in hunger; a 52 percent reduction in anxiety; an 18 percent boost in happiness; a 39 percent decrease in appetite; 40 percent less food cravings; 50 percent less frequent desire for over-the-counter pain medicine such as Advil, Tylenol, ibuprofen; a 39 percent drop in desire for sweet foods; and a 39 percent drop in desire for savory foods.

“The study was intentionally formatted to cover a wide range of effects,” said Mr. Jaffee, of ECS Brands. “We wanted to learn the most that we could to set us up for subsequent studies.”

Scientists in the cannabis field see plenty of potential for the plant, and for THCV in particular. But as of now, many medical and scientific experts say, the marketing remains far ahead of the research, which means that companies are making promises about their products with little evidence.

And Wana’s Fit gummies are no different, according to experts consulted for this article. “This is contorting science to make money,” Dr. Haney said. “If it works, do the right study and publish the data. Let your peers review the findings. There could be something really interesting there, but I’m not buying this story.”

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