It’s no secret that fiber-rich foods are good for your health AND they fill you up and help you stay full longer. Now researchers at the Imperial College of London and the Medical Research Council think they know why. They recently identified a substance released when you eat fiber-rich foods. This compound is called acetate. Acetate is a type of short-chain fatty acid produced by bacteria in your intestinal tract.
What Happens When You Eat and Add Fiber to Your Diet?
As you know, when you eat a fiber-rich food, most of the fiber in that food can’t be broken down and absorbed by your body. Humans lack the enzymes necessary to break down most dietary fiber. Instead, fiber stays in your intestinal tract where bacteria break it down and ferment it. One of the products released by these bacteria when they chow down on the fiber you can’t digest is acetate.
Scientists originally thought acetate stayed in your large intestine where it might help keep the lining of your large intestine healthy and, possibly, lower the risk for colon cancer. It now appears that acetate has far-reaching effects that extend all the way to your brain.
Researchers discovered large amounts of acetate in the guts of mice after they ate a high-fat diet rich in a fiber called inulin. More importantly, when they scanned their brains, they found acetate in their brains too. Specifically, they found acetate in a portion of the brain called the hypothalamus. What is one of the functions of the hypothalamus? It controls appetite. Bingo!
Then they tried another experiment. They injected mice with acetate directly. When the mice got acetate placed directly into their bloodstream, colon or brain, it reduced the amount of food they ate, just as fiber does. Researchers believe once acetate reaches the brain it changes the expression of neuropeptides that control appetite. This is another way fiber-rich diets may work in your favor when you’re trying to lose weight.
Another reason fiber is so filling and satisfying is that it forms a thick, gelatinous material when it enters your intestines. This slows down movement of fiber through your digestive tract so you feel fuller longer.
Other Ways Fiber Suppresses Appetite
Most research shows high-fiber diets reduce hunger, but fiber has other health benefits as well. A number of studies show a link between diets high in fiber and lower body weight. Not surprising since fiber is satiating. One study showed consuming an additional 14 grams of fiber daily was linked with a 10% decrease in food intake. Unfortunately, the average person in the United States only takes in about 15 grams of fiber a day. That falls short of the American Heart Association’s recommendation of 25 grams to 30 grams of fiber daily.
High-fiber diets also help with blood sugar control. This makes fiber an important dietary component for people with type 2 diabetes or metabolic syndrome. Some research also shows high-fiber diets lower the risk of getting type 2 diabetes in the first place. Fiber slows down the absorption of carbohydrates from the digestive tract. This reduces their impact on blood sugar and insulin.
In addition, soluble fiber reduces the absorption of cholesterol from the digestive tract. This helps to lower LDL-cholesterol. Therefore, diets rich in fiber may lower your risk for heart disease. Research shows consuming more fiber from cereal grains, fruits and vegetables is linked with a reduced risk for coronary artery disease, the most common cause of death in both men and women.
Types of Fiber
There are two main types of fiber – soluble fiber and insoluble fiber. Soluble fiber is the type most closely linked with blood sugar control, satiety and cholesterol-lowering. Soluble fiber readily dissolves in water, forming a thick gel that moves slowly through your digestive tract. The other type of fiber, insoluble fiber, doesn’t dissolve in water. Instead, it moves through your intestines without being broken down. Therefore insoluble fiber has a laxative-like effect.
What foods are highest in fiber? Fruits and vegetables are a good source of both soluble and insoluble fiber. Oatmeal, beans, lentils, and psyllium are excellent sources of soluble fiber. Insoluble fiber is abundant in whole grains, wheat bran, nuts, and seeds. For overall health, you should add both types of fiber to your diet
Adding More Fiber to Your Diet
Now that you know how fiber keeps you full and helps you control your weight, in addition to its other health benefits, what are some simple ways to add more fiber to your diet?
Start early. Begin the day with a bowl of hot, whole-grain cereal. Oatmeal is a good choice but quinoa is even better since it’s also high in protein. Sprinkle flaxseed and berries into your cereal to super-charge the fiber content of your cereal.
Choose non-starchy vegetables as side dishes and substitute quinoa or brown rice for white rice.
Snack on nuts. They’re a good source of fiber and healthy fats.
Substitute beans and lentils for some of the meat you’re currently eating.
Make sure the bread you eat is whole-grain or whole-wheat – not white bread.
Add beans to salads and soups. Sprinkle chopped nuts and seeds on salads.
Enjoy fresh fruit for dessert – and eat the peel. The peel is a good source of insoluble fiber. If you eat the skins, choose organic fruit. Did you know an apple has four grams of fiber? Plus, it’s loaded with healthy phytochemicals and antioxidants.
Use high-fiber flour when baking rather than white flour. Flaxseed flour and coconut flour are good choices.
The Bottom Line?
Adding more fiber to your diet doesn’t have to be hard. Be conscious of how you can add more fiber to every meal. You’ll feel fuller and more satisfied. Plus, you’ll be doing good things for your health.
Nature Communications. “The short-chain fatty acid acetate reduces appetite via a central homeostatic mechanism”
Medical News Today. “Discovery of Anti-Appetite Molecule Released by Fiber Could Help Tackle Obesity”
Appetite. 2011 Feb;56(1):65-70.
WebMD. “The Benefits of Fiber: For Your Heart, Weight, and Energy”
Nutrition Reviews. Volume 59, Issue 5, pages 129-139, May 2001.
Am J Clin Nutr April 2000 vol. 71 no. 4 921-930.
JAMA Internal Medicine. “Dietary Fiber and Risk of Coronary Heart Disease”
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