Fake Fiber Doesn’t Keep you Full

A new study published in the Journal of the Academy of Nutrition and Dietetics recently took a look at the effect of functional fibers on satiety. They wanted to find out whether or not an increased intake of fiber would result in satiety.

Evidence is amassing about the effect of increased fiber intake on satiety (the feeling of fullness). But whether or not these effects are realized from functional (added) fibers as well as they are from intact fibers remains to be seen.


Food and science concept. Dietitian. Nutrition.
Food and science concept. Dietitian. Nutrition.

The researchers from the University of Minnesota had a very interesting research plan. They examined four different types of functional (fermentable) fibers that are commonly found added to foods and beverages that are traditionally low in fiber (hence, the “fake” fiber moniker):

  • Oligofructose
  • Inulin
  • Soluble corn fiber
  • Resistant wheat starch

The Experiment 

They recruited 22 women aged 18-40 with a BMI between 18-29, from the low end of healthy weight to overweight BMI categories.

The participants were fed chocolate crisp bars with 10 g of their assigned fiber with a no-fiber bar acting as a control. Participants were then routinely administered a questionnaire asking details about feeling of fullness and were subject to breath analysis tests to determine rates of fermentation.


By analyzing hydrogen breath excretion, the researchers found that oligofructose, inulin, and soluble corn fiber were fermented in the colon, whereas resistant wheat starch was not. They were unable to determine any variation in the level of fullness based on different fiber bar consumption, stating that, “No differences were found in subjective satiety during the morning or food intake at lunch or over 24 hours.”

Their Conclusion

From this research, the researchers found out something interesting. The main conclusions that can be drawn from this research are the following.

  • The most gas and bloating occurred with the oligofructose bar
  • Chronic consumption of fermentable fibers may be required to provide satiety benefits
  • Variations in physical characteristics and how types of fiber are processed in and interact with the human GI tract influence physiologic effects
  • One fiber type may not elicit the physiologic effects of another, such as inducing a feeling of satiety
  • It is difficult to assign specific effects to single food ingredients that may or may not act differently depending on food structure and interactions within that food matrix

Although the study sample size was small, it does drive home the idea that all fibers are not created equal.

Your best bet? Stick to foods that are naturally high in fiber – like whole grains, fruits, vegetables, and legumes – and don’t bank on fake fibers to keep you feeling full.

FAQ- Fake Fiber Doesn’t Keep you Full

Various legumes and different kinds of nuts walnuts kernels ,hazelnuts, almond kernels,brown pinto ,soy beans ,flax seeds ,chia ,red kidney beans and pecan set up on white wooden table.
Various legumes and different kinds of nuts walnuts kernels ,hazelnuts, almond kernels,brown pinto ,soy beans ,flax seeds ,chia ,red kidney beans and pecan set up on white wooden table.

1. Are proteins and fibers effective in making sure you feel full for longer?

Fullness is a feeling that comes with your stomach having adequate food. However, there are some foods that have the capability of making you feel full for longer.

They are this way because our body takes time in breaking them down. The longer they stay in our stomachs, the longer we feel that we do not need to eat.

Protein and fiber are examples of foods that do that. Fiber especially makes you feel full immediately while protein helps you stay feeling full for longer. 

Because of these properties, proteins and fibers are great when you are trying to lose weight. For around the same (if not less) amount of calories, you stay full for twice as long. 

Foods like nuts are high in fiber, fat, and protein which makes them a perfect snack for helping you stay full for longer. The way fat works are that it interacts with our body’s natural hormones that tell us to stop eating because we are full.

2. Why do I keep eating fibers and still don’t feel full?

If you want to feel full and stay feeling full for longer, fibers are your best bet. Fibers are often high volume and low in calories which means that we physically feel full but have not eaten as many calories. 

Additionally, fibers break down pretty slowly. Due to this slow breakdown, they stay in our stomachs for longer. Hence, we feel full for longer. 

If you do not feel full even after consuming fiber, you probably have Leptin resistance. Leptin is a naturally occurring hormone in our body whose job is to send signals to our brain when the stomach is full. In normal circumstances, it is usually high after we eat.

Leptin resistance is a condition that causes a person to not respond as it should to leptin. As a result, you never feel full. 

Leptin is a hormone that tells the brain when the stomach is full. Leptin levels usually rise after a person eats a meal. Leptin resistance is a condition in which the body does not respond properly to leptin. This may result in a person not feeling full after eating a meal.

3. Is fiber good for weight loss?

Yes, fiber is great for weight loss because we cannot digest fiber. Fiber helps us feel full because it is quite a high-volume food. However, our bodies are incapable of digesting fiber.

Due to this, it helps us feel full without adding many calories to our food. Digestible fibers take long to digest as well so they too are great to add bulk to our food.

Fiber is a great way to make you feel like you’ve eaten a lot and is perfect for those who hate feeling hungry and overall empty. 

4. What kind of fiber helps you feel full for longer?

There are many kinds of fibers however, it is a soluble fiber that is the most beneficial for us. Soluble fibers help slow down the speed with which our body empties our stomach. 

Due to this slow process, food remains in our stomach for longer and hence we feel like we are sull hours after we have eaten a meal. 

Soluble fibers also slow down the speed with which sugar from the food is introduced into our bloodstream. The slowing down of this process is very beneficial as it helps our bodies to maintain steady levels of energy and prevents sugar spikes. 


With all the research and information in front of you, it is quite evident that there are glaring differences between natural and synthetic fibers. Natural fibers are infinitely more superior than fake fibers. The latter can cause many issues and we believe they are best avoided.