The "F" in F-Factor Is For Fiber (35 Grams a Day!) — an Expert Explains Why This Diet Is Harmful

"Eat carbs, dine out, drink alcohol, work out less." That's what the F-Factor Diet website says, which seems enticing — and also too good to be true. The F-Factor Diet isn't brand new (it's actually been around since 2007!), but it's gaining steam in the media as people have been coming forward so share their experiences with dangerous side effects. Before we delve into that, let's take a look at what the F-Factor Diet is and get registered dietitian Brenna O'Malley, creator of the virtual private practice The Wellful, to weigh in.

What Is the F-Factor Diet?

F-Factor was created by New York registered dietitian Tanya Zuckerbrot, and the website explains that the F-Factor approach focuses on combining lean proteins with high-fiber carbohydrates, which are low in calories and keep you feeling full throughout the day. So this is essentially a diet that focuses on eating tons of fiber — that's what the "F" stands for in F-Factor.

What Are the Steps of the F-Factor Diet?

The F-Factor diet has three steps. In step one, which is supposed to last two weeks, dieters eat at least 35 grams of fiber a day, and less than 35 grams of net carbs (your total grams of carbs minus grams of fiber). In step two, which you stay on until your weight-loss goal is achieved, aim for 35 grams of fiber per day and 75 grams of net carbs per day. For step three, the maintenance phase, keep going with the 35 grams of daily fiber, but enjoy less than 125 grams of net carbs. For sources of fiber, we're talking lots of beans, veggies, fruits, and whole grains. Of course they also promote eating the high-fiber bars and powders they sell, and this brand of high-fiber crackers called GG.

The website says the amount of fiber they recommend is what the Academy of Nutrition and Dietetics recommends for daily consumption, which is 25 grams a day for women and 38 grams for men. But F-Factor recommends at least 35 grams per day — that's a lot more!

Why Is Fiber Important on the F-Factor Diet?

"By eating more fiber, you will lose weight safely, steadily and naturally, and naturally improve your health and overall well-being," as stated on F-Factor's website. Why so much fiber? The website says it adds bulk to your food, slows down digestion, and boosts your metabolism, because your body attempts to break it down (even though it can't), which burns calories.

That part about fiber increasing your metabolism isn't true, though, as O'Malley explained that there is a minimal effect or increase on the thermic effect of food (TEF), which is how much energy it takes for your body to burn food. She said, "To eat a certain food to boost your metabolism is really emphasized by diet culture." She added that your body uses energy to digest all foods, and saying that eating certain foods to increase that expenditure is not realistic.

O'Malley said that the focus of the F-Factor Diet is on one basic nutrient: fiber. She added while fiber is an important component of many aspects of our overall health and eating as it's important for digestion and regularity, and can reduce the risk of cardiovascular disease, it's not the end all be all. Fiber does keep us full, which can help with weight loss, but fullness is only a piece of the picture.

We need to be sure we're consuming enough calories, nutrients, and also that we're enjoying our food. O'Malley explained that if you focus only on getting the recommended 35 grams of fiber, but you don't get enough calories or carbs, you may feel full, but not have enough energy to get through your day. She said that this is why when you see diets or products that advertise "keeping you full," remind yourself that fullness without eating enough calories or nutrients is essentially tricking your body to eat less, and that is not healthy overall.

What Are the Risks of the F-Factor Diet?

Of course, eating tons of fiber can cause digestive upset, including not-so-fun issues like bloating, stomach pains, constipation, or diarrhea, especially if you're not used to eating tons of fiber and you jump straight into eating 35 grams a day. But some people have anonymously come forward to influencer Emily Gellis Lande about the negative side effects they've experienced from following the F-Factor Diet. In an interview on the Juicy Scoop podcast and in an New York Times article, Lande said many shared that they've suffered from more dangerous symptoms from using the powders specifically, such as hives and other long-lasting skin issues like armpit rashes, as well as migraines, canker sores, hair loss, and severe gastrointestinal distress including intense cramps and rectal bleeding.

Followers of the F-Factor Diet also anonymously told Lande, which was shared in the New York Times article, that the diet encourages disordered eating, and O'Malley agreed. We all have different needs and all live in a diet culture world where we are constantly hearing the message that we need to change what we're eating with an emphasis on weight loss and being thin. And we do these things at whatever cost to our physical and mental health — it's normalized, O'Malley explained.

If a program encourages restricting calories to a very low amount, cutting out certain foods, meticulously tracking grams and calories, or replacing certain foods with supplements, "it can be a red flag that some of these actions can easily dip over into disordered or obsessive eating, especially if you are prone to these or have perfectionist tendencies," O'Malley said.

On the F-Factor website, they also sell intentions bracelets, and the description on the website says to wear them on your dominant hand, "as a daily visual reminder to honor your intentions for looking and feeling your best so that you never settle for mediocrity." There's a note on the bracelet's packaging that reads, "This is the hand that holds the fork, reaches for the bread basket, or dips into the candy dish." It supports the BS message that foods are "good" or "bad," and encourages you to not eat "bad" foods, and makes you feel guilty if you do, which can be so mentally damaging!

Can You Do the F-Factor Diet Long-Term?

The program advertises that it's meant to be a long-term way of eating, and if someone wants a "restart," they can go back to Phase 1: the calorie and carbohydrate restricted phase. The program encourages counting grams of fiber, net carbs, and consuming GG fiber crackers with meals, O'Malley explained. The website said, "GG crackers will keep you feeling full, allowing you to lose weight without hunger while receiving numerous health benefits." O'Malley said, "When programs keep you reliant on those external factors, my question for clients is: 'how would you feel if you didn't have these crackers with you? Are you able to enjoy spontaneous, flexible eating? What if you didn't know how many calories or carbs were in a food?'" This doesn't seem like an enjoyable, sustainable way of eating for the rest of your life.

Is the F-Factor Diet Recommended For Weight Loss?

The desire for weight loss is normal and doesn't make you a "bad" person, O'Malley said. Wanting to change your body and wanting to feel better about your relationship with food aren't at opposite sides of the spectrum; they can exist at the same time. "We live in a culture and society where weight loss is so highly valued that I want to emphasize that you're not wrong for wanting that or it being a priority for you," she said. If you're curious about your relationship with food and your body, she recommends reaching out to a HAES-aligned dietitian and therapist to help you feel safe about exploring what's important to you in a respectful, client-focused environment. What you choose to do from there is up to you!