F-Factor, Heavy Metals, and Influencers: Maybe the Real Toxin Is Diet Culture

Tanya Zuckerbrot of the F-Factor Diet Cooks With Jessica Alba
Tanya Zuckerbrot of the F-Factor Diet Cooks With Jessica Alba
Photo: Jamie McCarthy (Getty Images)

The F-Factor Diet is said to give a person more stamina, clear up their skin, and improve their sex life. Models love it; it’s the preferred diet of the Miss Universe pageant; at least one Fox Blonde has said she uses it and that it definitely works. Supermodel Olivia Culpo says it keeps her “radiant. Jessica Alba and Megan Kelly have separately appeared with the F-Factor’s CEO, the latter endorsing it explicitly on her show. You can eat carbs, go out to eat wherever you like, keep up your drinking habits, work out less, and still lose weight. It’s the perfect lifestyle for a Manhattan socialite, a diet that says a person can drop pounds and still drink rose on the beach: According to one the diet’s high-profile adherents, F-Factor founder Tanya Zuckerbrot just “gets the way people live.


Zuckerbrot, an influencer and registered dietician, has made a very good living helping the elite lose weight. Under the umbrella of her brand, F-Factor, Zuckerbrot has convinced people like Katie Couric and Molly Sims to shell out $15,000 for an F-Factor “startup package,” a program that at the time centered around the consumption of appetite suppressant crackers.

Wealthy people willing to sacrifice in the pursuit of a small body are Zuckerbrot’s target demographic: For $10,000, Zuckerbrot will shepherd clients through high-fiber, low-carb weight loss plans; for an additional $1,500 per appointment, she’ll either guide them through the grocery store or reorganize their pantry. Premium customers have praised the celebrity dietician for being just a phone call or text away: If a high-powered lawyer is dining at Per Se, for instance, Zuckerbrot’s staff will review the menu beforehand and tell him what to eat.

But for those who can’t afford such personalized attention, there are Zuckerbrot’s books, along with F-Factor’s brand of diet bars ($29.99 for a box of 12) and protein powders ($44.99 a bag) which promise similar results at a fraction of the cost. But they also bring with them, a number of Zuckerbrot’s customers have recently claimed, bleeding colons, loss of a period, serious gastrointestinal issues, rashes, and a host of other side-effects.

Over the last few months, anonymous Instagram accounts and testimonies, many of them boosted by the fashion influencer Emily Gellis, have claimed Zuckerbrot’s program has caused them significant physical or psychological harm; aggrieved former clients detail hospital visits, serious gastrointestinal complications, and eating disorder relapses after following the F-Factor Diet or using its branded supplements. The allegations, which first appeared on a smattering of Instagram accounts, rose to prominence over the last two weeks as Gellis’ page became a clearinghouse for these accounts. By Tuesday, the New York Times had covered the controversy and Zuckerbrot, who just weeks ago had described the furor as “cyberbullying,” hired the high-powered lawyer Lanny Davis, perhaps best known for representing Michael Cohen.


According to the Times, at least one of the claims about Zuckerbrot’s products was made in bad faith. But the paper also spoke to women who reported rashes and emergency room visits they believed were caused by following F-Factor. Business Insider, additionally, interviewed four dieters who reported symptoms like hair loss and hives, though as the publication noted, their accounts were anecdotal.

As the New York Times mentions, and as is very clear from browsing Gellis’s stories, there’s a prominent theory that Zuckerbrot’s powders and diet bars are literally poisoning people. Seizing onto a California state mandate—which requires disclosing the potential for trace amounts of metals in nearly any product—some have come to the conclusion that Zuckerbrot’s line of diet supplements contain toxic levels of lead.


Heavy metal poisoning is a common fear—if a relatively rare diagnosis for adults who don’t work with toxic materials or live in Flint. But speculation about its broad range of symptoms and potential therapies is popular in the naturopathic and wellness communities: In 2015, Goop’s most-read story was an article written by a “medical medium” called “Are Toxic Heavy Metals Ruining Your Life?”

Zuckerbrot has categorically denied that her products contain dangerous levels of lead and tells Jezebel through a spokesperson “our products are 100% safe, all natural, and contain no harmful ingredients.” Meanwhile, on Tuesday, Gellis told The Times she was soliciting samples of F-Factor products to test.


The FDA leaves the regulation of dietary supplements more or less to the companies that produce them. And one non-profit, the Clean Label Project, has found significant toxins in some brands of protein powders, so the theory is technically plausible. But given the high fiber content of Zuckerbrot’s products, along with the known affects of extreme low-calorie or low-carbohydrate diets, it seems likely some issues could be the result of how people are using the program itself, even without a nefarious secret ingredient.

It’s the Occam’s razor of wellness: If a person experiences gastrointestinal issues or the loss of a period from consuming as few as 1,000 calories a day, most of them intentionally difficult to digest, maybe the diet’s just not that healthy. Maybe the conspiracy isn’t a toxin but the extreme constraints inspired by the program itself.


Zuckerbrot, most recently enshrined in the gossip pages for trying to conceal that she had fled New York during the pandemic, is a longtime fixture in the city’s upper echelons. In the years before her Instagram celebrity—she now has over 116,000 followers—she was frequently photographed at swanky events in the Hamptons and Manhattan. A one-time contributor to Fox News, the 47-year-old is a registered dietician and the author of two books detailing her high-fiber and low-carb plan—a plan which, as she is always eager to point out, definitely allows its adherents to keep drinking.


Originally, Zuckerbrot pushed Norwegian GG crackers, a trendy appetite-suppressing snack, as the backbone of her plan. But in 2018, she began offering her own line of diet bars and protein powders and incorporating them into “Step 1" of her diet. A year later, she and her husband, a managing partner at a real estate firm, bought a $22.5 million duplex on Park Avenue.

Broadly, the F-Factor Diet involves three steps: First, participants “kick-off” weight loss by consuming 35 grams of fiber every day (for comparison, the FDA recommends 28 grams for a 2,000 calorie diet) and only eating three servings of approved carbs, which are naturally limited to fruits, the aforementioned Norwegian cardboard crackers, or Zuckerbrot’s own products. Through the second and third phases of the diet, F-Factor allows a gradual increase of carbs, though as Zuckerbrot has noted, dieters can always go back through the steps if they’d like to lose additional weight.


Throughout the diet, a person consistently continues to get at least 35 grams of fiber every day. One easy way to fulfill this mandate—assuming you aren’t in a position to call up Zuckerbrot for advice every few hours—is to purchase her products, which are packed with fiber in the forms of an indigestible corn derivative and partially hydrogenated guan gum, a water-soluble fiber.

Like many businesses operating in California, F-Factor contains a Prop 65 disclosure, a warning about potential carcinogens which most notably also applies to businesses like Starbucks and Whole Foods based on their practice of serving coffee in the state. But it’s not hard to imagine that a person consuming large amounts of these supplements, or not much besides these supplements, in concert with a low-calorie diet, would face some serious ill effects.


Low carb diets have been said to come with their own unsavory long-term effects and it’s not generally a great idea to blast your system with a ton of fiber all at once, particularly if you’re forgetting to drink enough water. The guidelines focusing on approved portions of fiber and carbs may leave a person attempting to follow the program without the help of a celebrity dietician at something of a disadvantage when it comes to finding a balanced meal. When Refinery 29 did a story on the F-Factor controversy a few days ago, they spoke to a woman who claimed she followed the diet for six months but said she found it impossible to get in more than 1,000 calories a day given the constraints. Another woman, in Business Insider, said she usually came in under that number.

“Any diet that limits a person to 1,000 calories puts that person a semi-starvation state, and at high risk for many ailments,” says Gregory Aponte, a professor of nutritional sciences and toxicology at the University of California at Berkley. “The body thus goes into a survival mode. Reproductive hormones drop, immune system drops, major minerals are lost.” An average 25-year-old woman, he notes, needs 1,400 calories just to keep a regular body function, which doesn’t include walking and talking. To give one of many examples, says Aponte, a person consuming so few calories would find their bodies choosing to conserve gut functions by “limiting the number of absorptive cells it makes.”


Zuckerbrot disputes the idea that her diet is extremely low calorie, and that it introduces large amounts of fiber suddenly: “Our product labels make it
clear that anybody using the F-Factor program should read the F-Factor book, which details the proper way to use the F-Factor program to achieve better health,” she says, which contains warnings about suddenly increasing fiber intake or consuming too few calories. “Going forward we are committed to making it even clearer that customers should not be customizing the F-Factor program or taking it to unhealthy extremes.”

Bolstered by the Prop 65 warning and the suspicion that F-Factor powders contained dangerous levels of lead, Zuckerbort’s customers called for the company to release a detailed list of ingredients, a demand the company complied with on Thursday morning. According to the Certificate of Analysis posted on the company’s Instagram page, F-Factor powder is comprised of 0.014 parts per million of lead, a significantly lower ratio than dark chocolates tested by the FDA.


It seems likely there are culprits other than a known toxin in the influencer’s powders and bars: For the A-list clients shelling out tens of thousands of dollars for personalized meal plans and private sessions, the extremities of the diet are probably blunted somewhat by Zuckerbort’s nutritional expertise. But it’s obvious now, if it wasn’t before, that what the dietician is selling her premium clients is somewhat different than what is getting sold to everyone else.

Molly Osberg is a Senior Reporter with G/O Media.


Cheers Pink Ears!

It’s funny to me that the woman pushing this diet’s last name means Sugar Bread.

Just reading about the low calorie counts, and the way too much fiber at once, is making me anxious. I went through a bad time my junior year of college, eating about 800 calories per day, and I really can't believe I  did that to myself. Sometimes now, with a crazy work schedule,  I find myself slipping back into the eating disorder mode of thinking: It's good that you're so hungry you've moved past being hungry. I'm going to go eat a pre-dinner muffin now. Stay safe out there, eat as much food as you like.