Can the F-Factor Diet Help You Lose Weight Without Feeling Deprived?

Before you roll your eyes at another trendy-sounding diet, there are a few things you should know about the F-Factor Diet. No, the F doesn't stand for a four-letter word that you might yell when restricting foods in an effort to lose weight. It stands for fiber. Yes, that's right, plain ol' fiber.

The weight-loss program was created by Tanya Zuckerbrot, RD, almost by accident. "I pursued a fiber-based approach for fiber's clinical benefits," the New York-based dietitian tells LIVESTRONG.com, noting that her goal was to help lower people's cholesterol levels and help people with diabetes manage their blood sugar. "What I had not anticipated was weight loss," she says.

"Across the board, all of these patients were losing weight. They were living their lives normally, enjoying meals at their favorite restaurants, drinking alcohol and getting healthier in the process. This was the birth of the F-Factor Diet."

While it might sound like the magic bullet dieters everywhere are looking for, the F-Factor Diet is all about eating a balanced diet with an emphasis on fiber intake, Natalie Rizzo, RD, tells LIVESTRONG.com.

The eating plan prescribes eating three fiber-rich meals and a snack every day, as well as filling up on lean protein and healthy, complex carbohydrates. The target fiber number? At least 35 grams per day.

‌Read more:‌ Signs and Symptoms of Too Much Fiber in the Diet

But that amount isn't some magic number, Rizzo says. "It's actually not that much," she says, adding that it's the actually the upper recommended amount, according to the Academy of Nutrition and Dietetics. Most American adults only eat 15 grams of fiber per day, which means they're missing out on nutrient-dense foods.

‌The Benefits of Fiber‌

A February 2015 study looked at 240 adults with metabolic syndrome, which means they had high blood pressure, high blood sugar, high cholesterol and overweight. Those following a high-fiber diet — at least 30 grams per day — lost 4.6 pounds and were able to keep it off for a year, according to research published in the ‌Annals of Internal Medicine.‌

What's more, fiber has been linked to helping reduce your risk for heart disease, breast cancer and type 2 diabetes as well as preventing constipation, according to the Harvard School of Public Health.

"Fiber has the most incredible weight management and health benefits," Zuckerbrot says. "When it comes to weight management, fiber fills you up and keeps you feeling full for hours." Plus, it's technically calorie-free since it goes through your system undigested.

The F-Factor Diet is based on principles that basically go against everything people think about the weight-loss space, Zuckerbrot says. The lifestyle approach promotes eating the right carbs — fiber — as well as allows you to eat at restaurants and drink alcohol in moderation. The F-Factor Diet approach to weight loss and maintenance is broken out into three steps:

‌Step 1: Jumpstart Weight Loss‌

For two weeks you'll eat at least 35 grams of fiber and fewer than 35 grams of net carbs per day. (You can calculate net carbs by subtracting total carbs and the number of grams of fiber.) During these two weeks, you should avoid eating starches, including bread, cereal, pasta, rice, snack foods and baked goods; starchy vegetables, including corn, peas and potatoes; milk and yogurt; and high-fat meats. The diet also limits fruits to just one serving per day and prohibits fruit juice.

But unlike other fad diets, Zuckerbrot says, the F-Factor Diet does not completely eliminate an entire food group — in this case, carbohydrates.

‌Read more:‌ Everything You Need to Know About Carbs and Why You Shouldn't Cut Them

"The reason these foods are reintroduced in a structured manner is because it is important to gradually level out caloric intake to maintain a new weight rather than lose more or gain back," Zuckerbrot says.

‌Step 2: Continued Weight Loss‌

During step 2, you'll start to reintroduce foods that were excluded during step 1. In this step, add three more servings of carbs to your daily diet. You can choose starchy veggies, too — just make sure each serving clocks in at 15 grams of carbs. Continue eating 35 grams of fiber and less than 75 grams of net carbs per day.

‌Step 3: Maintenance Eating‌

Step 3 is really about maintaining this way of eating over the long term for weight loss and health benefits. Aim for at least 35 grams of carbs and less than 125 grams of net carbs per day.

"I think this approach is sustainable," Rizzo says. "You're not cutting out calories. [Tanya] even makes a point to say you can have a drink, you can still have dessert if you want to."

In one word, yes.

"When trying to lose weight, the portions usually get smaller," says Scott Keatley, RD. "Adding foods high in fiber can add a feeling of abundance to meals and convince your gut that you're full without having all the calories."

But, the word "diet" in the F-Factor Diet may be somewhat misleading, Rizzo says. After all, diets tend to be a short-term, often unsuccessful attempt at losing weight. But the F-Factor Diet promotes a change in lifestyle and can result in long-term weight loss and maintenance.

"The diet name could hurt [the approach] in the long run for people who don't necessarily know what it is," she says. "But you can do this [style of eating] without calling it the F-Factor Diet." For her own clients, Rizzo would recommend the program if they expressed interest in it, noting it's just a way to stick with a healthy, balanced diet.

And Keatley agrees: "If used properly, [the F-Factor Diet] is a great plan that doesn't eliminate any major food group."

One thing to watch out for, Zuckerbrot says, is consuming too much fiber too quickly, especially if you haven't been eating much to begin with. Ramping up fiber intake may lead to minor bloating and abdominal cramping, Zuckerbrot says, and recommends upping fiber intake slowly.

"That's why step 1 limits your fiber intake to three servings of high-fiber carbohydrates, making it unlikely that you will eat too much fiber too quickly," she says.

Zuckerbrot also recommends drinking lots of water, at least three liters per day. "Fiber needs water to work its magic," she says.

‌Read more:‌ Why the Satiating Diet May Be the Healthier Alternative to Keto