Here's the first surprising fact about fiber: It's a carbohydrate. But not just any carbohydrate. Because it's indigestible, fiber doesn't affect your body the way other carbs do.
Here's the second surprising fact: There are two major types of fiber. Soluble fiber dissolves readily in water and turns into a gel upon digestion. It takes a long time to digest and slows the release of other nutrients into the blood.
It's counterpart, insoluble fiber, doesn't dissolve in water. It enhances your body's ability to bulk up stool and keeps food moving through your digestive system.
I- Insulin control
B- Beneficial bacteria
Fiber's effect on satiety is usually attributed to two main factors: adding bulk to the diet and slowing down digestion. When you eat high-fiber foods, this increased bulk takes up more space in your stomach. This is directly related to fullness because your stomach is a "volume counter" rather than a "calorie counter." The more space you take up with food or fluids, the fuller you feel.
It's no wonder you can plow through a whole box of cereal but struggle to finish a second serving of broccoli. The high-fiber nature of the broccoli takes up more space in your stomach, which sends signals to your brain to put down the fork.
Additionally, foods high in soluble fiber slow digestion and absorption by creating a gel once ingested. A slower rate of digestion helps to keep you fuller between meals and allows satiety signals to be sent to your brain, which work to stop you from eating as much.
Another perk of slow digestion is enhanced insulin sensitivity and blood glucose control.[3,4] A high-fiber meal slows the entry of nutrients, such as glucose, into the blood. A slower release of glucose into the blood allows insulin to distribute it effectively. What's more, the pancreas doesn't need to secrete as much insulin.
Regardless of your goals, enhanced insulin sensitivity is invaluable. The ability to efficiently clear glucose from the blood and to effectively distribute it bodes well for body composition, regardless of your physique goal.
The beneficial bacteria in your gut feed on fiber. Increasing the amount of good gut bacteria has been shown to enhance immune function and reduce inflammation.[5,6]
A stronger immune system helps you get to the gym, rather than being stuck on the couch, sick, wrapped up in a blanket. You can't make progress if you're unable to get to the gym!
Reducing inflammation may reduce your risk of several metabolic abnormalities such as high blood pressure, insulin resistance, and high blood lipids.
Multiple studies demonstrate a positive association between the amount of fiber you eat in your diet and life expectancy.[7,8] A recent study looked at the dietary fiber intake of nearly half a million European adults and found that those eating more than 28 grams of fiber per day had a 24 percent less risk of death than those taking in less than 16 grams per day.
This doesn't mean a low-fiber diet will take away 25 percent of your years on earth, but it does suggest that eating a high-fiber diet may potentially add a few years. That means more time for squats and deadlifts!
A diet plentiful in insoluble fiber is effective at increasing fecal bulk and promoting a regularly scheduled trip to the bathroom. There's even some new research demonstrating that people who eat a diet higher in fiber may expend more calories through their poop than those consuming a low-fiber diet. The results may be miniscule, and more research is needed at this point, but, hey, it's another incentive to stay regular.
How Much Fiber Should I Consume?
The recommended intake for women is a minimum of 25 grams per day, whereas for men it is a minimum of 38 grams per day. More is not necessarily better. Excessive amounts of fiber can lead to GI distress, impaired nutrient absorption, and unintended weight loss. If you're continuously full, it's hard to eat enough!
How To Increase Daily Fiber Intake
If you're not eating enough fiber at the moment, have no fear, as there are many delicious high-fiber foods to choose from. Start with one meal, and swap in a high-fiber source—say, brown rice for white rice. Then, start increasing your vegetable intake, one meal at a time, until you're at 4-5 servings per day. Slow and steady is the key; otherwise, you may suffer cramps, excessive bloating, and gas.
Excellent Sources Of Fiber
- Soluble Fiber: Oats, nuts, seeds, beans, legumes, and some fruits and vegetables
- Insoluble Fiber: Whole-grains such as wheat and popcorn, fruits and vegetables (with peels)
When you increase your fiber intake, you should increase your fluid intake, too. Without adequate fluids, fiber can actually increase constipation and impede digestion.
What About Added Fiber?
Many processed foods now contain added fiber, also known as functional fiber. Dietary fiber comes from plants, but functional fiber, such as polydextrose and inulin, is isolated from natural sources and then added to foods such as cereals and bars. There is limited long-term research on the effects of functional fiber, but current literature suggests that the benefits may mirror those of dietary fiber.[13-15]
There are no known negative side effects to date, but the idea of adding fiber to processed foods allows many nutrient-poor foods to be deemed "healthy." Choosing fruits and vegetables over cereal bars and processed foods will be better for your nutrition plan as a whole.
- Phillips, R. J., & Powley, T. L. (1996). Gastric volume rather than nutrient content inhibits food intake. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 271(3), R766-R769.
- Wanders, A. J., van den Borne, J. J., de Graaf, C., Hulshof, T., Jonathan, M. C., Kristensen, M., ... & Feskens, E. J. (2011). Effects of dietary fibre on subjective appetite, energy intake and body weight: a systematic review of randomized controlled trials. Obesity Reviews, 12(9), 724-739.
- Lattimer, J. M., & Haub, M. D. (2010). Effects of dietary fiber and its components on metabolic health. Nutrients, 2(12), 1266-1289.
- Ismaiel, M., Yang, H., & Min, C. (2016). Dietary fiber role in type 2 diabetes prevention. British Food Journal, 118(4).
- D'Mello, C., Ronaghan, N., Zaheer, R., Dicay, M., Le, T., MacNaughton, W. K., ... & Swain, M. G. (2015). Probiotics improve inflammation-associated sickness behavior by altering communication between the peripheral immune system and the brain. The Journal of Neuroscience, 35(30), 10821-10830.
- Ganguli, K., Meng, D., Rautava, S., Lu, L., Walker, W. A., & Nanthakumar, N. (2013). Probiotics prevent necrotizing enterocolitis by modulating enterocyte genes that regulate innate immune-mediated inflammation. American Journal of Physiology-Gastrointestinal and Liver Physiology, 304(2), G132-G141.
- Chuang, S. C., Norat, T., Murphy, N., Olsen, A., Tjønneland, A., Overvad, K., ... & Teucher, B. (2012). Fiber intake and total and cause-specific mortality in the European Prospective Investigation into Cancer and Nutrition cohort. The American Journal of Clinical Nutrition, 96(1), 164-174.
- Park, Y., Subar, A. F., Hollenbeck, A., & Schatzkin, A. (2011). Dietary fiber intake and mortality in the NIH-AARP diet and health study. Archives of Internal Medicine, 171(12), 1061-1068.
- Cummings, J. H. (2001). The effect of dietary fiber on fecal weight and composition. CRC Handbook of Dietary Fiber in Human Nutrition, 3, 183-252.
- Trumbo, P., Schlicker, S., Yates, A. A., & Poos, M. (2002). Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein and amino acids. Journal of the American Dietetic Association, 102(11), 1621-1630.
- Duke University. (n.d.). Fiber—How Much Is Too Much? Retrieved from https://studentaffairs.duke.edu/sites/default/files/u110/TooMuchFiber082015.pdf
- Slavin, J. L. (2008). Position of the American Dietetic Association: health implications of dietary fiber. Journal of the American Dietetic Association, 108(10), 1716-1731.
- Konings, E., Schoffelen, P. F., Stegen, J., & Blaak, E. E. (2014). Effect of polydextrose and soluble maize fibre on energy metabolism, metabolic profile and appetite control in overweight men and women. British Journal of Nutrition, 111(01), 111-121.
- Cho, S. S., & Samuel, P. (Eds.). (2009). Fiber Ingredients: Food Applications and Health Benefits. CRC Press.
- Hutchinson, C., & Hollis, J. (2013). Effect of soluble fiber dextrin on postprandial appetite and subsequent food intake in healthy adults. The FASEB Journal, 27(1_MeetingAbstracts), 237-7.