For now, Medicare does not cover drugs prescribed specifically for weight loss, but it will cover GLP-1 class drugs if they’re prescribed for other conditions, such as Type 2 diabetes. Wegovy, for example, is covered if it is prescribed to reduce the risk of heart attack and stroke in adults with either obesity or overweight. But, in November, the Biden administration proposed reinterpreting Medicare prescription-coverage rules to allow for coverage of “anti-obesity medications.”
Such a move is reportedly part of the argument Lilly’s CEO plans to bring to the Trump administration. Rather than using drug price negotiations to reduce health care costs, Ricks aims to play up the potential to reduce long-term health care costs by improving people’s overall health with coverage of GLP-1 drugs now. This argument would presumably be targeted at Mehmet Oz, the TV presenter and heart surgeon Trump has tapped to run the Centers for Medicare and Medicaid Services.
“My argument to Mehmet Oz is that if you want to protect Medicare costs in 10 years, have [the Affordable Care Act] and Medicare plans list these drugs now,” Ricks said to Bloomberg. “We know so much about how much cost savings there will be downstream in heart disease and other conditions.”
An October report from the Congressional Budget Office strongly disputed that claim, however. The CBO estimated that the direct cost of Medicare coverage for anti-obesity drugs between 2026 and 2034 would be nearly $39 billion, while the savings from improved health would total just a little over $3 billion, for a net cost to US taxpayers of about $35.5 billion.
Elsewhere in the over 700-page proposal, the administration lays out policy that would bar Medicare Advantage plan providers from reopening and reneging on paying claims for inpatient hospital admission if those claims had already been granted approval through prior authorization. The proposal also wants to make criteria for coverage clearer and help ensure that patients know they can appeal denied claims.
The Department of Health and Human Services notes that when patients appeal claim denials from Medicare Advantage plans, the appeals are successful 80 percent of the time. But, only 4 percent of claim denials are appealed—”meaning many more denials could potentially be overturned by the plan if they were appealed.”
AI guardrails
Last, the administration’s proposal also tries to shore up guardrails for the use of AI in health care with edits to existing policy. The goal is to make sure Medicare Advantage insurers don’t adopt flawed AI recommendations that deepen bias and discrimination or exacerbate existing inequities.
As an example, the administration pointed to the use of AI to predict which patients would miss medical appointments—and then recommend that providers double-book the appointment slots for those patients. In this case, low-income patients are more likely to miss appointments, because they may struggle with transportation, childcare, and work schedules. “As a result of using this data within the AI tool, providers double-booked lower-income patients, causing longer wait times for lower-income patients and perpetuating the cycle of additional missed appointments for vulnerable patients.” As such, it should be barred, the administration says.
In general, people of color and people of lower socioeconomic status tend to be more likely to have gaps and flaws in their electronic health records. So, when AI is trained on large data sets of health records, it can generate flawed recommendations based on that spotty and incorrect information, thereby amplifying bias.
Pivotal Peptides—which is not a licensed pharmacy or dispensary—did not respond to the letter. Instead, its website was modified to indicate that it was “down for maintenance,” and the company instructed customers to email directly. About 10 days later, Pivotal Peptides’ registered agent, Elizabeth Gately, then sent an email (which Lilly obtained) instructing customers to place tirzepatide orders using coded language.
“Good News,” the email read, “Pivotal Peptides … is still in business!”
“If a favorite product (starting with T) was your go-to, that name can’t be used in any correspondence with me or listed on my price sheet anymore,” Gately allegedly wrote. “Therefore, I need another identifier and decided (for now) to call this peptide ’11mg.'”
Gately went on to say that the codenamed product “is Pivotal Peptide’s [sic] bestseller,” and “it is the only T size available from PP right now except by special order.” The letter ended with: “Remember to order ’11 mg’ with the latest price to identify the product you want, if applicable, and no longer use T in our communication.”
Pivotal Peptides did not respond to Ars’ request for comment.
In a statement emailed to Ars, a Lilly spokesperson said Pivotal Peptides and the other companies Lilly is suing are engaging in “conduct that poses serious risks to patient safety.” In the lawsuit, Lilly notes that even children could be ordering this DIY, research-grade drug.
“No one should ever be allowed to sell these untested, non-human grade or manipulated drugs to American consumers,” the statement continued.
Lilly’s lawsuits come amid a legal storm over compounded versions of the tirzepatide, which can be legally made by licensed pharmacies as long as tirzepatide is in shortage. On October 2, the Food and Drug Administration announced that the shortage had ended but then decided to reconsider the decision after being sued by compounding pharmacies.
On several occasions, the FDA has warned of safety concerns related to compounded versions of GLP-1 weight-loss drugs.
The judge in the case, District Judge Mark Pittman, granted the FDA’s request, canceling an October 15 hearing, and ordering the parties to submit a joint status report on November 21.
Drugmakers respond
The move was celebrated by the Outsourcing Facilities Association (OFA), which filed the lawsuit.
“We believe that this is a fair resolution in light of the agency’s rash decision to take the drug off of the list at a time when the agency has acknowledged ‘supply disruptions,’ which immediately created a major access issue for patients everywhere,” OFA Chairperson Lee Rosebush said in a statement. “Most important, should the FDA repeat its removal decision when a shortage still genuinely exists, we will return to court.”
The move is also likely to please patients who have come to rely on cheaper, more readily available compounded versions of the drugs. For some, compounded products may have been their only access to tirzepatide. Still, those drugs are not without risk. The FDA has repeatedly emphasized that compounded drugs are not FDA-approved and do not go through the same safety, efficacy, and quality reviews. And the agency has warned of dosing errors and other safety concerns with compounded versions.
The one party that is certainly unhappy with the FDA’s move is Eli Lilly, which had reportedly sent cease-and-desist letters to compounders. In an emailed statement to Ars, a spokesperson for Lilly said that there was sufficient supply of the company’s drug and continued use of compounded versions is unwarranted. “Nothing changes the fact that, as FDA has recognized, Mounjaro and Zepbound are available and the shortage remains ‘resolved,'” the spokesperson said.
Lilly also noted the FDA’s safety concerns about the compounded versions, adding that its own examination of some compounded products found impurities, bacteria, strange coloring, incorrect potency, puzzling chemical structures, and, in one case, a product that was just sugar alcohol.
“All doses of Lilly’s FDA-approved medicines are available and it is important that patients not be exposed to the risks in taking untested, unapproved knockoffs,” the spokesperson said.
In terms of the supply “disruptions” the FDA mentioned and that some patients and pharmacies have reportedly experienced, Lilly said that the supply chain was complex and there are many reasons why a given pharmacy may not have a specific dose at hand, such as limited refrigerated storage space.
Compounding pharmacies are suing the Food and Drug Administration so they can keep making imitation versions of popular—and lucrative—tirzepatide drugs, namely knockoffs of Mounjaro for diabetes and Zepbound for weight loss.
Generally, compounding pharmacies make customized formulations of drugs for patients with specific needs, like when a patient has an allergy to a filler ingredient or if a child needs a liquid version of a drug that normally comes as a capsule. But larger compounding operations are also legally allowed to make imitations of branded drugs if those drugs are in short supply, acting as a stopgap for patients.
Tirzepatide has certainly been in short supply in recent years. Given the high prevalence of diabetes and obesity in America and the drug’s effectiveness, demand for tirzepatide and other drugs in the new GLP-1 class have skyrocketed, and many patients have struggled to fill prescriptions. The FDA placed tirzepatide on its drug shortage list in December of 2022—and that’s where it remained until last week.
On October 2, the FDA announced that the tirzepatide shortage had been resolved and that the nation’s supply of GLP-1 drugs was stabilizing, though other drugs in the class, including semaglutide, remain in short supply.
“FDA confirmed with the drug’s manufacturer [Eli Lilly] that their stated product availability and manufacturing capacity can meet the present and projected national demand,” the agency said in its announcement. However, it cautioned that patients and prescribers “may still see intermittent localized supply disruptions” as the drugs move through the supply chain.
End of an era
With the resolution, compounding pharmacies are no longer able to produce tirzepatide. And the FDA highlighted the point to the drug makers, writing in bold that the agency “reminds compounders of the legal restrictions on making copies of FDA-approved drugs.”
Buying counterfeit weight loss drugs from illegal online pharmacies that don’t require prescriptions is, in fact, a very bad idea, according to a study published Friday in JAMA Network Open.
The counterfeit drugs are sold as equivalents to the blockbuster semaglutide drugs, Ozempic and Wegovy, which are prescription only. When researchers got their hands on three illegal versions, they found that the counterfeit drugs had low-purity semaglutide, had dosages that exceeded the labeled amount, and one had signs of bacterial contamination.
The three substandard drugs tested came from three different illegal online pharmacies, which sold them as generic semaglutide drugs for weight loss, appetite suppression, diabetes, and cardiovascular health. However, the researchers, led by scientists at the University of California, San Diego, and the University of Pécs in Hungary, had initially tried purchasing counterfeit drugs from six such sellers.
Three of the illegal pharmacies, which specifically sold Ozempic knockoffs, never delivered the drugs after researchers paid for them. Instead, the researchers were hit with “nondelivery” scams, in which the sellers requested additional, hefty payments, supposedly needed to get through customs. These extra fees ranged from $650 to $1,200—much more than what the researchers paid for small dosages of the counterfeit drugs, which ranged from $113 to $360 across the six sellers.
Rogue pharmacies
The Ozempic scams were run out of the rogue online pharmacies: weightcrunchshop.com, puremedsonline.com, and genius-pharmacy.com. The three pharmacies that delivered dubious drugs included semaspace.com, uschemlabs.com, and biotechpeptides.com.
Two of the sellers—semaspace.com and uschemlabs.com—have already received warning letters from the Food and Drug Administration for selling unapproved, misbranded drugs. At the time of publication, the Semaspace website was no longer reachable. The US Chem Labs site was still available, but their semaglutide vials were all listed as out of stock.
The study’s findings, while unsurprising, highlight the risk people may take in efforts to get hold of the popular drugs. Steep prices, lack of insurance coverage, and drug shortages have kept the drugs out of reach for many who could benefit from them. Compounding pharmacies have stepped in to make copycat versions. While these are legal and can come from legitimate pharmacies—ones that are properly registered and require prescriptions—they also carry risks. Compounded drugs are not approved by the FDA and may pose safety and efficacy risks. Last week, the FDA warned of increasing reports of people overdosing on semaglutide products made in compounding pharmacies, leading some patients to be hospitalized.
Enlarge/ Wegovy is an injectable prescription weight-loss medicine that has helped people with obesity.
The US Food and Drug Administration has approved two injectable versions of the blockbuster weight-loss and diabetes drug, semaglutide (Wegovy and Ozempic). Both come in pre-filled pens with pre-set doses, clear instructions, and information about overdoses. But, given the drugs’ daunting prices and supply shortages, many patients are turning to imitations—and those don’t always come with the same safety guardrails.
In an alert Friday, the FDA warned that people are overdosing on off-brand injections of semaglutide, which are dispensed from compounding pharmacies in a variety of concentrations, labeled with various units of measurement, administered with improperly sized syringes, and prescribed with bad dosage math. The errors are leading some patients to take up to 20 times the amount of intended semaglutide, the FDA reports.
Though the agency doesn’t offer a tally of overdose cases that have been reported, it suggests it has received multiple reports of people sickened by dosing errors, with some requiring hospitalizations. Semaglutide overdoses cause nausea, vomiting, abdominal pain, fainting, headache, migraine, dehydration, acute pancreatitis, and gallstones, the agency reports.
Bad math
In typical situations, compounding pharmacies provide personalized formulations of FDA-approved drugs, for instance, if a patient is allergic to a specific ingredient, requires a special dosage, or needs a liquid version of a drug instead of a pill form. But, when commercially available drugs are in short supply—as semaglutide drugs currently are—then compound pharmacies can legally step in to make their own versions if certain conditions are met. However, these imitations are not FDA-approved and, as such, don’t come with the same safety, quality, and effectiveness assurances as approved drugs.
In the warning Friday, the FDA said that some patients received confusing instructions from compounding pharmacies, which indicated they inject themselves with a certain number of “units” of semaglutide—the volume of which may vary depending on the concentration—rather than milligrams or milliliters. In other instances, patients received U-100 (1-milliliter) syringes to administer 0.05-milliliter doses of the drug, or five units. The relatively large syringe size compared with the dose led some patients to administer 50 units instead of five.
Enlarge/ The figure demonstrates how syringe size could lead some to an incorrect dosage.
FDA-approved semaglutide drugs, meanwhile, are dosed in milligrams and come in standardized concentrations. The agency received several reports of health care providers incorrectly converting from milligrams to units or milliliters, leading them to calculate the wrong dosages. With these math errors, some patients administered five to 10 times more semaglutide than intended.
“FDA recognizes the substantial consumer interest in using compounded semaglutide products for weight loss,” the agency wrote. “However, compounded drugs pose a higher risk to patients than FDA-approved drugs.” The agency urged patients and prescribers to only use compounded versions when absolutely necessary.
Enlarge/ Ozempic is a GLP-1 drug for adults with type 2 diabetes.
For patients with Type 2 diabetes, taking one of the new GLP-1 drugs, such as Ozempic, is associated with lower risks of developing 10 out of 13 obesity-associated cancers as compared with taking insulin, according to a recent study published in JAMA Network Open.
The study was retrospective, capturing data from over 1.6 million patients with Type 2 diabetes but no history of obesity-associated cancers prior to the study period. Using electronic health records, researchers had follow-up data for up to 15 years after the patients started taking either a GLP-1 drug, insulin, or metformin between 2008 and 2015.
This type of study can’t prove that the GLP-1 drugs caused the lower associated risks, but the results fit with some earlier findings. That includes results from one trial that found a 32 percent overall lower risk of obesity-associated cancers following bariatric surgery for weight loss.
In the new study, led by researchers at Case Western Reserve University School of Medicine, some of the GLP-1-associated risk reductions were quite substantial. Compared with patients taking insulin, patients taking a GLP-1 drug had a 65 percent lower associated risk of gall bladder cancer, a 63 percent lower associated risk of meningioma (a type of brain tumor), a 59 percent lower associated risk for pancreatic cancer, and a 53 percent lower associated risk of hepatocellular carcinoma (liver cancer). The researchers also found lower associated risks for esophageal cancer, colorectal cancer, kidney cancer, ovarian cancer, endometrial cancer, and multiple myeloma.
Compared with insulin, the researchers saw no lowered associated risk for thyroid and breast cancers. There was a lower risk of stomach cancer calculated, but the finding was not statistically significant.
Gaps and goals
The GLP-1 drugs did not show such promising results against metformin in the study. Compared with patients taking metformin, patients on GLP-1 drugs saw lower associated risks of colorectal cancer, gall bladder cancer, and meningioma, but those calculations were not statistically significant. The results also unexpectedly indicated a higher risk of kidney cancer for those taking GLP-1 drugs, but the cause of that potentially higher risk (which was not seen in the comparison with insulins) is unclear. The researchers called for more research to investigate that possible association.
Overall, the researchers call for far more studies to try to confirm a link between GLP-1 drugs and lower cancer risks, as well as studies to try to understand the mechanisms behind those potential risk reductions. It’s unclear if the lower risks may be driven simply by weight loss, or if insulin resistance, blood sugar levels, or some other mechanisms are at play.
The current study had several limitations given its retrospective, records-based design. Perhaps the biggest one is that the data didn’t allow the researchers to track individual patients’ weights throughout the study period. As such, researchers couldn’t examine associated cancer risk reductions with actual weight loss. It’s one more aspect that warrants further research.
Still, the study provides another promising result for the blockbuster, albeit pricy, drugs. The researchers suggest extending their work to assess whether GLP-1 drugs could be used to improve outcomes in patients with Type 2 diabetes or obesity who are already diagnosed with cancer, in addition to understanding if the drugs can help prevent the cancer.
Enlarge/ Lars Fruergaard Jorgensen, chief executive officer Novo Nordisk A/S, during an interview at the company’s headquarters in Bagsvaerd, Denmark, on Monday, June 12, 2023.
After some persuasion from Sen. Bernie Sanders (I-Vt.), the CEO of Novo Nordisk will testify before lawmakers later this year on the “outrageously high cost” of the company’s diabetes and weight-loss drugs—Ozempic and Wegovy—in the US.
CEO Lars Jørgensen will appear before the Senate Committee on Health, Education, Labor, and Pensions (HELP), which is chaired by Sanders, in early September. The agreement came after a conversation with Sanders in which the CEO reportedly “reconsidered his position” and agreed to testify voluntarily. As such, Sanders has canceled a vote scheduled for June 18 on whether to subpoena Novo Nordisk to discuss its US prices, which are considerably higher than those of other countries.
The independent lawmaker has been working for months to pressure Novo Nordisk into lowering its prices and appearing before the committee. In April, Sanders sent Jørgensen a letter announcing an investigation into the prices and included a lengthy set of information requests. In May, the committee’s investigation released a report suggesting that Novo Nordisk’s current pricing threatens to “bankrupt our entire health care system.”
Sanders has repeatedly hammered not only the high prices of Novo Nordisk’s two blockbuster drugs but also the huge disparity between US prices and those in other countries.
Up to 15x more in the US
“Novo Nordisk currently charges Americans with type 2 diabetes $969 a month for Ozempic, while this same exact drug can be purchased for just $155 in Canada and just $59 in Germany,” Sanders wrote in April. “Novo Nordisk also charges Americans with obesity $1,349 a month for Wegovy, while this same exact product can be purchased for just $140 in Germany and $92 in the United Kingdom.”
Yale researchers, meanwhile, published a study in JAMA in March estimating that both drugs could be manufactured for less than $5.
In May, Novo Nordisk responded with a letter to Sanders, arguing that blame for high prices in the US lies with the country’s complex health system and with middle managers who take cuts, according to Bloomberg. Novo Nordisk said in the letter that it is prepared to address “systemic issues so that everyone who can benefit from its medicines is able to get them,” the outlet reported. The company also said it has spent over $10 billion on research and development to bring Wegovy and Ozempic to the market.
Still, that number is small in comparison to the projected revenue from the drugs. Bloomberg noted that analysts estimate that Novo Nordisk will make $27 billion from the two drugs this year alone. The May analysis by the HELP committee found that if just half of the adults in the US with obesity start taking a new weight-loss drug, such as Wegovy, the collective cost would be around $411 billion per year. Another report by the Congressional Budget Office found that the drugs’ costs are so high that they will not be offset by any financial gains from improved health outcomes.
“The Committee looks forward to Mr. Jørgensen explaining why Americans are paying up to 10 or 15 times more for these medications than people in other countries,” Sanders said last week.
As new diabetes and weight-loss drugs help patients curb appetites and shed pounds, food manufacturers are looking for new ways to keep their bottom lines plump.
Millions of Americans have begun taking the pricey new drugs—particularly Mounjaro, Ozempic, Wegovy, and Zepbound—and millions more are expected to go on them in the coming years. As such, food makers are bracing for slimmer sales. In a report earlier this month, Morgan Stanley’s tobacco and packaged food analyst Pamela Kaufman said the drugs are expected to affect both the amounts and the types of food people eat, taking a bite out of the food and drink industry’s profits.
“In Morgan Stanley Research surveys, people taking weight-loss drugs were found to eat less food in general, while half slashed their consumption of sugary drinks, alcohol, confections and salty snacks, and nearly a quarter stopped drinking alcohol completely,” Kaufman said. Restaurants that sell unhealthy foods, particularly chains, may face long-term business risks, the report noted. Around 75 percent of survey respondents taking weight-loss drugs said they had cut back on going to pizza and fast food restaurants.
Some food makers aren’t taking the threat lightly. On Tuesday, the massive multinational food and beverage conglomerate Nestlé announced a new line of frozen foods, called Vital Pursuit, aimed directly at people taking GLP-1 weight-loss drugs (Wegovy and Ozempic). Nestlé—maker of DiGiorno frozen pizzas and Stouffer’s frozen entrées—said the new product line will include frozen pizzas, sandwich melts, grain bowls, and pastas that are “portion-aligned to a weight loss medication user’s appetite.” The frozen fare is otherwise said to contain fiber, “essential nutrients,” and high protein, food features not specific for people on GLP-1 drugs.
“As the use of medications to support weight loss continues to rise, we see an opportunity to serve those consumers,” Steve Presley, CEO of Nestlé North America, said in the product line announcement. “Vital Pursuit provides accessible, great-tasting food options that support the needs of consumers in this emerging category.”
Nestlé isn’t alone. At the end of last year, WeightWatchers began offering a membership program for people taking GLP-1 drugs. In January, meal delivery service Daily Harvest announced its “GLP-1 Companion Food Collection.” And last month, GNC announced a “GLP-1 support program” for people on the drugs, which includes a collection of various supplements, coaching, and consultations.
The companies seem to be heeding the advice of analysts. Morgan Stanley’s report noted that food makers can adapt to people’s changing diets by “raising prices, offering ‘better for you’ or weight-management products, or catering to changing trends with vegan or low-sugar options.” Kaufman noted that some companies are already adjusting by selling smaller packages and portions.
Enlarge/ Packaging for Wegovy, manufactured by Novo Nordisk, is seen in this illustration photo.
With the debut of remarkably effective weight-loss drugs, America’s high obesity rate and its uniquely astronomical prescription drug pricing appear to be set on a catastrophic collision course—one that threatens to “bankrupt our entire health care system,” according to a new Senate report that modeled the economic impact of the drugs in different uptake scenarios.
If just half of the adults in the US with obesity start taking a new weight-loss drug, such as Wegovy, the collective cost would total an estimated $411 billion per year, the analysis found. That’s more than the $406 billion Americans spent in 2022 on all prescription drugs combined.
While the bulk of the spending on weight-loss drugs will occur in the commercial market—which could easily lead to spikes in health insurance premiums—taxpayer-funded Medicare and Medicaid programs will also see an extraordinary financial burden. In the scenario that half of adults with obesity go on the drug, the cost to those federal programs would total $166 billion per year, rivaling the programs’ total 2022 drug costs of $175 billion.
In all, by 2031, total US spending on prescription drugs is poised to reach over $1 trillion per year due to weight-loss drugs. Without them, the baseline projected spending on all prescription drugs would be just under $600 billion.
The analysis was put together by the Senate’s Health, Education, Labor, and Pensions (HELP) committee, chaired by staunch drug-pricing critic Bernie Sanders (I-Vt). And it’s quick to knock down a common argument about the high prices for smash-hit weight-loss drugs. That is, with their high effectiveness, the drugs will improve people’s health in wide-ranging ways, including controlling diabetes, improving cardiovascular health, and potentially more. And, with those improvements, people won’t need as much health care, generally, lowering health care costs across the board.
But, while the drugs do appear to have wide-ranging, life-altering benefits for overall health, the prices of the drugs are still set too high to be entirely offset by any savings in health care use. The HELP committee analysis cited a March Congressional Budget Office (CBO) report that found: “at their current prices, [anti-obesity medicines] would cost the federal government more than it would save from reducing other health care spending—which would lead to an overall increase in the deficit over the next 10 years.” Moreover, in April, the head of the CBO said that the drugmakers would have to slash prices of their weight-loss drugs by 90 percent to “get in the ballpark” of not increasing the national deficit.
The HELP committee report offered a relatively simple solution to the problem: Drugmakers should set their US prices to match the relatively low prices they’ve set in other countries. The report focused on Wegovy because it currently accounts for the most US prescriptions in the new class of weight-loss drugs (GLP-1 drugs). Wegovy is made by Denmark-based Novo Nordisk.
In the US, the estimated net price (after rebates) of Wegovy is $809 per month. In Denmark, the price is $186 per month. A study by researchers at Yale estimated that drugs like Wegovy can be profitably manufactured for less than $5 per month.
If Novo Nordisk set its US prices for Wegovy to match the Danish price, spending to treat half of US adults with obesity would drop from $411 billion to $94.5 billion, a roughly $316.5 billion savings.
Without a dramatic price cut, Americans will likely face either losing access to the drugs or shouldering higher overall health care costs, or some of both. The HELP committee report highlighted how this recently played out in North Carolina. In January, the board of trustees for the state employee health plan voted to end all coverage of Wegovy and other GLP-1 drugs due to the cost. Estimates found that if the plan continued to cover the drugs, the state would need to nearly double health insurance premiums to offset the costs.
Intermittent fasting, aka time-restricted eating, can help people lose weight—but the reason why may not be complicated hypotheses about changes from fasting metabolism or diurnal circadian rhythms. It may just be because restricting eating time means people eat fewer calories overall.
In a randomized-controlled trial, people who followed a time-restricted diet lost about the same amount of weight as people who ate the same diet without the time restriction, according to a study published Friday in Annals of Internal Medicine.
The finding offers a possible answer to a long-standing question for time-restricted eating (TRE) research, which has been consumed by small feeding studies of 15 people or fewer, with mixed results and imperfect designs.
The new study—led by Nisa Marisa Maruthur, an internal medicine expert at Johns Hopkins—has its own limitations and, like any one study, isn’t the last word on the matter. But “it takes us one step closer to identifying the underlying mechanisms of TRE,” nutrition experts Krista Varady and Vanessa Oddo of the University of Illinois wrote in an editorial accompanying the study. “Using a controlled feeding design, Maruthur and colleagues show that TRE is effective for weight loss, simply because it helps people eat less.”
The study involved 41 people, 21 who followed a time-restricted diet for 12 weeks and 20 who ate a usual eating pattern (UEP). Most of the participants were Black women (93 percent) with obesity and either pre-diabetes or diet-controlled diabetes, limiting the generalizability of the findings. But the study carefully controlled what and when the participants ate; each participant got controlled meals (breakfast, lunch, dinner, and snack) with identical macro- and micro-nutrients. Each participant was assigned a calorie level for their meals based on an established, standardized equation that estimates baseline caloric need. They were told to maintain their current exercise level, which was monitored with a wrist-worn accelerometer.
No magic necessary
In the time-restricted group, people only ate in a 10-hour window between 8 am and 6 pm, with 80 percent of their total daily calories consumed before 1 pm. In the usual eating group, people ate between 8 am and midnight, with 55 percent of their calories eaten after 5 pm for dinner and a night-time snack. In each eating group, participants were given specific windows of a couple of hours in which they should eat each pre-made meal. The participants ate three meals each week at a research site, where dieticians addressed adherence issues, and their eating was carefully monitored with the use of food diaries and urine tests. Approximately 96 percent of people in both groups followed the schedules to within 30 minutes. Diet adherence—eating all their assigned food and not eating outside food—was also high, with 93 percent in the time-restricted group and 95 percent in the usual eating group.
At the end of the 12 weeks, both groups lost about the same amount of weight, an average of around 2.4 kg (5.3 pounds), with no statistically significant difference between the two groups. The researchers also found no differences between the two groups in their glucose homeostasis, waist circumference, blood pressure, or lipid levels.
“Our results indicate that when food intake is matched across groups and calories are held constant, TRE, as operationalized in our study, does not enhance weight loss,” Maruthur and her colleagues concluded. The authors are upfront about the limitations of the study, though, noting that the results could have been different in different groups of people and potentially in shorter time-restricted windows, such as eight hours instead of 10. They called for more research to explore those questions.
Outside experts applauded the study while also adding that it’s not surprising. “The headline finding that TRE does not magically lead to more weight loss sounds sensational but is also obvious,” Adam Collins, a nutrition expert at the University of Surrey, said.
Naveed Sattar, a professor of cardiometabolic medicine at the University of Glasgow, called the study “well done.” It “tells us what we expected—that there is nothing magical about time-restricted eating on weight change other than effects to reduce caloric intake,” he said. “If time-restricted eating helps some people eat less calories than they would otherwise, great.”
The experts Varady and Oddo, meanwhile, see it as a boon for anyone trying to lose weight. “Many patients stop following standard-care diets (such as daily calorie restriction) because they become frustrated with having to monitor food intake vigilantly each day,” they wrote in their commentary. “Thus, TRE can bypass this requirement simply by allowing participants to ‘watch the clock’ instead of monitoring calories while still producing weight loss.” It’s a “simplified” and “accessible” dietary strategy that anyone can follow, including lower-resource populations, the researchers wrote.
