What Is the F-Factor Diet? Is It Safe?
Of the many different ways, there are to eat for weight loss, some emphasize portion size, while others focus on eliminating specific foods or food groups. Others still zero in on macronutrients and prescribe a specific ratio of fat and protein to carbohydrates. And at least one diet that’s gained much attention recently focuses its emphasis on a single nutrient: fiber.
Developed by Tanya Zuckerbrot, an internationally known dietitian, the F-Factor diet bills itself as “the most liberating approach to weight loss and optimal health.” It claims to be based on scientific evidence and insists that following the rules will allow dieters to eat carbs, drink alcohol, eat meals in restaurants and work out less while still losing weight.
In 2006, Zuckerbrot released “The F-Factor Diet: Discover the Secret to Permanent Weight Loss,” which has since led to the development of the F-Factor company, which helps dieters follow the program by offering the book, supplements, and food items that comply with the diet’s tenets.
Fiber for Weight Control
Erin Holley, a registered dietitian at the Ohio State University Wexner Medical Center in Columbus, says “The main premise for the F-Factor diet is to follow a high-fiber, high-protein diet,” which encourages choosing high-fiber carbohydrates such as fruits and vegetables and whole grains. “It also recommends consumption of lean proteins and healthy fats” and discourages consumption of processed foods and refined grains, carbs, and added sugars and sweets.
“Depending on what phase of the diet you’re following, it can include upwards of 35 to 60 grams of fiber per day,” Holley notes. The idea is that you’ll feel fuller with all that fiber, and that can help you lose weight because you’ll end up consuming fewer calories over the course of the day.
A Phased Approach
The average American only eats about 15 grams of fiber per day, but USDA Dietary Guidelines recommend women should aim for at least 25 grams daily; men should consume 33 grams of fiber per day. The F-Factor diet goes further and recommends even higher levels of fiber intake.
The diet breaks down into three phases. “Each phase gradually increases the amount of fiber and carbohydrates,” Holley explains.
- Step 1: This phase usually lasts about two weeks. You’ll consume 1,000 to 1,200 calories and 35 grams of fiber per day. Dieters should also eat fewer than 35 grams of net carbs (total carbohydrates minus fiber) and six servings of fat per day.
- Step 2: This phase lasts until you’ve reached your goal weight. You’ll consume a little less than 1,300 to 1,500 calories per day, increasing net carbs to 75 grams per day while still aiming for a minimum of 35 grams of fiber per day. You’ll add an additional three servings of carbs and three servings of fat.
- Step 3: This is the maintenance phase that lasts for the rest of your life, theoretically. In this phase, you’ll eat 1,600 to 2,000 calories per day depending on your height and weight, and you’ll consume 125 grams of net carbs per day while still maintaining that minimum of 35 grams of fiber per day.
While a minimum of 35 grams of fiber per day is the magic number for the F-Factor diet, the company notes that “many people following F-Factor get upwards of 60 grams of fiber per day, as there is no upward limit as to how much you can eat.”
However, dieters are cautioned to slowly increase fiber intake and level off when you find the upper amount you can tolerate. Dieters are also encouraged to drink plenty of water – about three liters per day – to help the fiber do its job.
Because it’s a very low-calorie diet, you’re likely to lose weight when switching over. The high fiber content means you’ll likely feel less hungry when reducing calories.
The F-Factor diet is backed by the F-Factor company that sells powders and bars that contain 20 grams of fiber and 20 grams of protein. Naturally, the company encourages dieters to purchase their products. They also have registered dietitians available for one-on-one and group nutritional counseling.
Who’s This Diet For?
Generally speaking, most of us would benefit from increasing the amount of fiber in our diets, but you’d be best served by checking with your health care professional first to make sure any dietary alteration is a good idea for you and your unique health needs.
Holley says she avoids “recommending specific diets for any of my clients” because most diets fail or only work temporarily while you’re following it carefully. “There is potential for this diet to result in weight change or other effects, at least temporarily. However, we also know that diets fail, and 95% of dieters gain the weight back, plus some. Most diets can be very restrictive and can have side effects from cutting out entire food groups for extended periods.”
The F-Factor diet may be difficult for some people to stick with long term because it can be restrictive and it can be challenging to consume as much fiber as indicated.
Holley also cautions that anyone with a history of an eating disorder, chronic dieting, or disordered eating patterns should steer clear because the counting of carbs and fiber could exacerbate an existing issue or trigger additional disordered eating behaviors.
High Fiber Foods
Holley notes that “if you’re simply looking to increase fiber naturally in your diet, you wouldn’t need to purchase the book or these specific products. There are plenty of natural ways to increase fiber, such as increasing intake of fresh, whole fruits, vegetables and whole grains.”
High-fiber foods you should seek to add include:
- Beans and legumes, such as lentils, chickpeas, and kidney beans.
- Nuts and seeds.
- Broccoli and other cruciferous vegetables.
- Berries, apples, and other whole fruits with the skin left on.
- Carrots, beets, sweet potatoes, and other root vegetables.
- Quinoa, oatmeal, and other whole grains.
Incidents of GI Distress
In addition, people who have gastrointestinal issues such as IBS or sensitivities to FODMAP foods may also want to give this diet a pass because “changing to a very high-fiber diet could increase some symptoms,” Holley says.
“FODMAPs are sugars, or carbohydrates, that are found in certain foods,” says Shelley Wood, a registered dietitian nutritionist with Santa Clara Valley Medical Center in San Jose, California. “FODMAP stands for fermentable oligo-di-monosaccharides and polyols.”
FODMAPs are “naturally found in many nutritious foods that we normally eat, but some people may be sensitive to them,” says Melissa Perry, a registered dietitian with Orlando Health in Orlando, Florida. “FODMAPs can draw extra water into your digestive tract and be fermented by the bacteria in your gut. Someone with a low tolerance for these FODMAPs may feel bloated, gassy, and have abdominal pain or diarrhea.”
Holley notes that these GI symptoms have led to “thousands of complaints about this diet in particular,” which has led some people to question whether it’s safe.
Is F-Factor Safe?
This diet, like many others that seek to help people lose weight, “emphasizes the importance of consuming more fruits, vegetables, whole grains, lean proteins and healthy fats,” Holley notes. So it’s not extraordinary in that sense, and that’s generally a good idea.
However, “where it differs is by recommending a much higher level of fiber, beyond what’s recommended by the USDA. The USDA recommends 25 to 35 grams of fiber per day for most adults,” as compared to the upwards of 60 grams of fiber some dieters on the F-Factor plan will consume daily – and that can lead to GI distress.
“In addition, the F-Factor diet and company recommend purchasing their powders and bars, which can be expensive and may lead to even higher fiber intakes,” Holley says. “There have also been reports that these supplements may contain lead, arsenic and other compounds that could be harmful to health.” Some of these reports originated via social media and were surfaced by a social media influencer who’s now being sued by the company.
In response to the allegations that their products might be harmful, the company released an independently performed certificate of analysis (used to ensure that test results confirm a product meets certain specifications) to the TODAY show in August. Supplements aren’t regulated by the FDA, and companies that make such products are not required to list their ingredients. The company released its CoA, which was corroborated by two independent nutritionists hired by NBC News, as a show of good faith that its products are safe for consumption. The CoA found that while there were indeed trace levels of these elements, the levels were not high enough to cause harm.
The company notes that because the products it sells are natural, “they do contain a small amount of trace metals, as anything grown in the soil can. This is no cause for concern; strawberries, spinach and rice, even when grown organically, will contain trace metals.”
The company offers additional information on its website about trace metals in its products. Also, the bars contain whey protein – whey is a common allergen, which could be the cause of some of the reports of GI issues.
Regarding various complaints the company has received, Zuckerbrot issued the following statement: “We are proud of our company and of the hundreds of thousands of our customers and clients who have used the F-Factor diet and products safely for good health and a nutritious diet. The F-Factor diet book was first published over 14 years ago, and it has been endorsed by countless nutritionists and physicians. Out of 174,000 distinct orders in the last 2+ years, we have had only 50 health-related complaints, less than.03 percent of total orders, and we will always work with our customers to identify and resolve any issue they’re having to ensure they can use our product safely. We have facts and science to support our results.”
Adopting a Sustainable Lifestyle
If you’re considering adopting the F-Factor diet – or any other diet for that matter – Holley urges you to consider what that means. “Consider if you can maintain this way of eating for the rest of your life. There’s no doubt that consuming a higher fiber diet on a regular basis has health benefits,” she says. “However, I do think it may be unrealistic for many to consume above 35 grams of fiber daily, considering most adults only get an average of 15 grams of fiber per day.”
But she also notes that “including more whole foods that are naturally high fiber is a great choice and can be very cost-effective. You do not need to purchase a specific book or supplemental products to do that.”