Food Products with Added Fiber May Not Reduce Hunger

Eating food products with added fiber may not reduce hunger, according to a recent study.

Dietary fiber, also referred to as roughage or bulk, is the part of a plant that cannot be digested or absorbed by the body. Adding fiber to the diet is thought to help keep the bowels regular and possibly treat or prevent certain diseases. Dietary fiber is found in grains, fruits and vegetables. There is no fiber in animal products such as meat, fish, eggs or dairy products. Soluble fiber can be found in foods such as oat bran, apples, citrus, pears, peas, beans, potatoes, seeds, oranges, grapefruit and psyllium (a plant product used in common over-the-counter bulk laxative and fiber supplement products such as Metamucil). Soluble fiber is dissolved in water and forms a jelly-like bulk inside the small intestine, which may help to lower cholesterol and reduce blood sugar.

In a new study, researchers assigned 22 women of normal body weight to eat five different chocolate crisp bars in random order. Four of the bars contained 10 grams of one of the following fibers: oligofructose, inulin, soluble corn fiber or resistant wheat starch. The fifth bar contained no added fiber and was used as a control. Each participant received a bar at dinner and then a bar of the same fiber type in the morning. Participants were randomly assigned each fiber type and switched treatments until all participants had been given all five bars. Hunger and fullness feelings were evaluated as the main outcome measures.

The researchers found that participants reported similar feelings of hunger and fullness while on all five bar types. All fiber types were well-tolerated; however, gastrointestinal symptoms were more common for the oligofructose bar.

The authors concluded that adding fiber to chocolate bars may not reduce hunger or alter food intake in the short term. Larger-scale, well-designed clinical trials are needed to confirm these findings.

Along with dietary fiber, whey protein has also been studied for its potential effects on hunger. As a source of high nutritional quality protein, it has been found to reduce short-term food intake and may aid in reducing appetite. Additional studies are required before firm conclusions can be made.

For more information about integrative therapies that may suppress appetite, please visit Natural Standard's Comparative Effectiveness Database.

For more information about a high fiber diet, please visit Natural Standard's Health & Wellness Database.

Comments

[J Squared]

I agree with the previous commenter, that different people metabolize foods in various ways and that how quickly or slowly people feel hungry again depends on their metabolism. I’ve recently read that a study done by researchers at Purdue University, that peanuts and peanut butter can decrease appetite and increase satiety for two and half hours as compared to just eating rice cakes only, which only decreased hunger for 30 minutes. It was concluded that a combination of the protein as well as the fiber in the peanuts was the reason in increasing satiety. So maybe fiber does play a role in hunger after all.

[nb]

The design of the study is flawed and the results of the study are undoubtedly questionable, but the question of added fiber providing the feeling of fullness may be different for individuals with different metabolism. I have hypoglycemia, and once I feel hunger, I need to eat a large volume of carbohydrates for me to not feel so hungry and sick. Eating apples, which have soluble fiber, when I'm hypoglycemic makes matters worse and I start getting nauseated and start shaking and sweating profusely until I feel so weak. Different people need different amount of food to feel satiated, and the eating schedule may differ from person to person. I think that the study needs to be focused on a specific patient population and address other metabolism and medical condition issues to gain validity.

[nh]

There is no doubt arguing the benefits fiber can provide. As someone who has tried to lose weight over the past few years and someone who tried to increase fiber intake, I do not totally believe the results of this study. In my experience, adding more fiber to my diet allowed me to lower my total calorie intake. Also, I believe this study design was poor. There were many variables that could affect the results. I agree with the author when they said that a large, well-designed study is needed to evaluate the true benefits fiber has in decreasing appetite.

[ss]

You have to have fiber stay in the stomach to feel full but that doesn't happen normally. After intake, fiber moves quickly to the colon due to lack of enzymatic activity in stomach and intestine towards it. As a result it doesn't reduce hunger but help with bowel movement only.

[weezy]

I have to disagree with this article. I personally feel more full and satisfied when I eat foods that are high in fiber. I don't think we can base much off of these studies considering the sample size was so small. I think it also would have made a difference in the results had they used foods that are natural sources of high fiber, not manufactured bars with added fiber.

[CW]

I agree that larger studies need to be conducted to verify the findings of this small study. Although I heard that food with fiber is supposed to make people feel more full, I did not think that fiber increases satiety. A study like this is difficult to apply the general population because there are a lot of variables in the types of foods we eat and how people process foods. Personally, when I eat foods that are high in fiber (fruit, oatmeal, etc...), I feel full initially, but then I feel hungry shortly after. However, other people may disagree.

[ee]

This is an interesting study and I can relate to it. I buy fiber containing bars to help me get through the day between meals, but I find myself feeling even hungrier within the next hour. I look forward to reading more about this study.

[Jessica]

I was surprised by the outcome of this study, however I am concern how about robust it is. If participants served as their own controls, was there an appropriate washout period? It was also a very small sample size, and a very short term study, and these are huge limitations. Chocolate bars may also not be the best food to use, since it may trigger the women to want more chocolate and thus to be more hungry. Additionally, body mass index (BMI) of these women ranged from 18 to 29, and anything over 25 is overweight so that may have also played a factor as well. This is an interesting idea but I would like to see more research before conclusions are drawn.

[LO]

I would also like to see details about this study. It would be interesting to see a similar trial with a longer study period, maybe a week of eating the same type of fiber bar. It seems like so many different things can change day-to-day (amount of energy needed, other foods that were eaten, etc.) It may provide more accurate results if it looked at a longer time period. Either way, fiber is still good for us and is necessary for a well-balanced diet!

[AR]

This is surprising to me as well. Everywhere you read, it is said that fiber reduces hunger, help you stay fuller longer, etc. This study was small (only 22 women)though. To be honest, I agree with what others above have written: Fiber has never made me feel less hungry as well. When I did a quick search, I found that the NIH's exact words on their website are that "it makes you feel full faster, it can be helpful in controlling weight". I think the benefits of fiber have been drilled into our minds so much, it will be a while before many people jump on this train.

[rgg]

This is quite and interesting study. I firmly believed that fiber induced satiety on the body, since it was a bulk-forming agent. I would like to see this study expanded out to a longer duration, 5 days does not seem too adequate. In addition, knowing more information on patient demographics and activity levels would be key.

[SMK]

I agree with many of the comments posted on this blog. I am taking this study's findings with a grain of salt because of the study setup and design. Just as the authors concluded, I would want to see larger-scale, well-designed clinical trials to confirm these findings. Since there aren't really any severe adverse side effects to fiber, I don't see a downside for people to take it if they are trying to lose weight or curb hunger, even if the results are just placebo effect.

[anonymous]

This is really interesting to me. Like a lot of the other posters, I would really like to see more research done on this topic. For someone like myself, by only eating one granola bar for dinner and one for breakfast, I would be starving no matter what the case. Therefore, it’s interesting to me that the study was designed this way. I think that future studies may have the potential to be better designed. However, despite what the evidence says, I will still be incorporating fiber as a means to keep a well balanced diet.

[anonymous]

This is definitely the opposite of what I have heard, but not surprising to me. In actuality, I can attest to the results of this study. I have never noticed a difference in how long until I get hungry with high fiber granola bars and those without high fiber. Whenever I grab a high fiber granola bar, its at times when I want to feel fuller or when I know I wont be able to sit down for a meal for an extended period of time. But every time I have done this, I still get hungry when I normally would have anyways. I think it will be interesting to see if any more data comes out that will confirm these results.

[ams]

I would like to know more details about this study. It would be interesting to see how variables were controlled for, like daily activity level and caloric/fat intake outside of the bars administered in the study. From the sounds of it, this study only took place over five days. Would consuming the same type of fiber daily for weeks or months make a difference? What if each bar had a higher fiber content? It would also be interesting to see if appetite-related hormones, like leptin, are effected by fiber intake.

One method I've used to help make myself feel fuller is simply drinking a large glass of water before meals. The water takes up some of the room in my stomach so I can effectively eat less while experiencing satiety. But being that I love to eat, that doesn't always mean I stop when I'm no longer hungry...

[Nicole]

It is interesting to see that not any one of the fibers seemed to make a difference. I recently read a meta- analysis that discussed the use of added fiber in reduction of symptoms of IBS and the results varied based on the type of fiber studied. I agree, larger scale studies should be done before making any conclusions- the study may not have been adequately powered and there are a lot of potential confounding variables with such a subjective outcome. Great post!

[AS]

Although this study did not show a benefit from fiber in reducing feelings of hunger I think it is important to note that foods high in fiber are still an important part of a healthy diet and lifestyle. I think it would be more beneficial clinically to evaluate the incorporation of high fiber foods into a person's daily diet and the resulting effect on feelings of hunger and weight loss/management. Feelings of hunger could be affected by numerous things. If you are eating a ton of fiber but still only consuming very few calories you are going to be hungry because you body needs fuel. I definitely think more studies need to be done.