High-fiber Diets and Weight Loss
By Kathleen M. Zelman, MPH, RD, LD
Reviewed By Brunilda Nazario, MD
If you’re overweight and want some help losing weight, start eating foods high in fiber. Dietary fiber is not a magic weight loss weapon, but it has the power to help fill you up without filling you out.
Here’s why: One of the most effective ways to lose those extra pounds is to control hunger, the dieter’s Achilles heel. Hunger is affected by many things, including when you eat, and the composition of your meals — the amount of fats, carbohydrates, protein, fiber, and water content.
Eating healthy high-fiber foods makes you feel full, so you can resist eating more food than you need. Fibrous foods also can take longer to chew, giving your brain time to get the signal that you have had enough to eat.
Read on to learn about losing weight by eating a high-fiber diet.
How Dietary Fiber Helps Weight Loss
Studies show that most people eat about the same weight of food each day, says Barbara Rolls, PhD, author of The Volumetrics Eating Plan. If you choose high-fiber, water-rich foods — such as broth-based vegetable soups, salads, fruits, and vegetables — instead of foods without fiber and water, you can eat the same weight of food but feel full on fewer calories.
A 2009 study in the journal Appetite compared the satiety or fullness factor of apples, applesauce, and apple juice with added fiber before lunch. People who ate an apple before lunch ate 15% fewer calories than those who ate the applesauce or drank apple juice. This suggests that the fiber in the whole apple was more filling even when compared to the juice that had added fiber.
Beyond the fiber content, crunching and chewing a whole piece of fruit stimulates your senses and takes longer to eat. So psychologically, it may also be more satisfying than beverages or soft foods. Chewing also promotes saliva and the production of stomach juices that help fill the stomach.
Fiber at Breakfast Is a Healthy Weight Loss Habit
In its tracking of the eating habits of successful dieters — those big losers who have kept weight off for years — the National Weight Control Registry has found that most eat breakfast regularly. And cereal is one of their morning rituals.
In general, eating cereal — especially high-fiber cereals — is beneficial for weight loss, says fiber expert Joanne Slavin, PhD, RD, a professor at the University of Minnesota in St. Paul and member of the 2010 Dietary Guidelines Advisory Committee. “Studies that look at what people eat show those who eat more carbs, more fiber, and cereal in general weigh less than those who eat less fiber, carbs, and cereal.”
How Much Dietary Fiber Do You Need?
Most women should get at least 25 grams and most men 38 grams each day to gain all the health benefits of fiber, according to the Institute of Medicine’s Dietary Reference Intake. The problem is that most Americans get only about half that when not on a diet and even less when dieting, especially on low-carb diets.
Tufts University researcher and professor of nutrition Susan Roberts, PhD, has shown that people who eat 35 to 45 grams of fiber a day are less hungry when losing weight and lose more weight than people who eat less fiber. (But beware of consuming fiber as a bulk laxative; it can sap your body of needed nutrients and vitamins.)
“There is no downside to eating a diet rich in fiber,” Slavin says. “And the potential health gains are significant.”
Does Type of Fiber Affect Weight Loss?
Fibers come in a variety of forms:
- Fiber is either soluble or insoluble: Soluble dissolves in water, insoluble does not. Both of these types are fiber are found naturally in fruits, vegetables, whole grains, legumes, and nuts.
- “Dietary” fiber refers to the fiber found naturally in the foods that we eat.
- “Functional” fibers such as inulin are added to packaged foods to boost their fiber content. These fibers are isolated or extracted from a plant or animal source, or they are manufactured.
Although all fiber is healthy, research indicates that fiber from whole foods may aid weight loss the most – likely because those high-fiber foods are also low in calories.
“As a registered dietitian, I always say ‘food first,'” Slavin tells WebMD.
“No one fiber is perfect, so eating a wide variety of fibers is the perfect solution to gain all the health benefits of fiber,” Slavin says. “Not only will you trim your waistline with a high-fiber diet rich in fruits, vegetables, whole grains, legumes, and nuts, but also reduce the risk for heart disease, diabetes, obesity, diverticulitis, and constipation.”
Add Fiber Calories Wisely and Slowly
Slowly adding more fiber to your diet can avoid bloating and gas by giving your body time to adapt. It is also important to drink plenty of liquids while increasing fiber.
Try these tips for adding more low-calorie foods to your meal plan to boost fiber while keeping calories in check:
- Eat whole fruits instead of fruit juice.
- Snack on veggies.
- Make vegetables a main course.
- Add a filling vegetable salad instead of a starchy salad as a side dish with meals.
- Enjoy a bowl of vegetable-based broth soup before meals.
- Start the day with a high-fiber cereal topped with fruit and low-fat dairy.
- Eat more beans.
- Make all your grains whole and limit them to a few servings each day.
- Add nuts and seeds to your weight loss plan, but keep the portions small because they are high in fiber and calories.
Experts are quick to point out that fiber alone won’t peel off the pounds. You still need to eat a healthy, calorie-controlled diet and get regular physical activity. But controlling or maintaining your weight is easier with a diet rich in fiber.