Fiber is a fantastic ingredient contributing to weight loss, disease prevention, and optimum health. This unique substance has been found in research studies to increase satiety (the feeling of fullness after eating)), reduce hunger, and help people eat fewer calories.
The Types Of Fiber
There are two types of dietary fiber- soluble and insoluble fiber.
Soluble fiber is the type of fiber that dissolves in water and turns into a gel-like substance. It bypasses your digestive system intact and is not digested until it reaches your colon, where its microorganisms ferment (digest or break down) the soluble fiber. It enhances digestive health and supports the body’s absorption of nutrients.
The subclasses for soluble fiber are:
You can naturally get inulin from “leeks, asparagus, onions, wheat, garlic, chicory, oats, soybeans, and Jerusalem artichokes.” Chicory root is the best food source of inulin, providing you with an incredible 42 g of inulin per 100 grams of chicory.
Oats, barley, mushrooms, and cauliflower are excellent sources of beta-glucan. According to this study, oats and barley are the two highest sources of beta-glucan.
Insoluble fiber does not dissolve in water. Instead, it absorbs and holds water like a sponge and bypasses your entire digestive system intact – not even the microorganisms in the colon can break it down. It provides bulk to the stool by keeping it moist and easier to eliminate.
The subclasses for insoluble fiber are:
Good sources of cellulose are:
- Cereals and grains.
- Root and leafy vegetables.
- Some fruits such as pears and apples.
A typical food source for hemicellulose is bran cereals and mustard greens.
How Does Fiber Help You Lose Weight?
A new January 2022 study (See Section 3.1) breaks down exactly how it helps you lose weight:
- Fiber can block fat absorption (reduces your intake of fat)
- It can reduce energy intake (AKA – calorie intake).
- Enhances satiety
- Fiber can absorb water, making you feel fuller.
- It can create short-chain fatty acids (SCFAs) when fermenting in the intestines. This process enhances satiety.
- Fiber can produce two hormones called glucagon-like peptide (GLP-1) and PYY Peptide YY (PYY), appetite suppressants.
Other ways fiber can help you lose weight:
- Fiber-rich foods are low-energy-density. (You’ll feel like you ate a lot of food, but your calorie intake will be low).
- Fiber helps regulate your body’s carbohydrate conversion to sugar, thus supporting sugar stability to help you lose weight by controlling hunger and sugar levels.
- “A high-fiber diet excretes more energy (calories) than the energy provided by the extra fiber, thus resulting in a negative energy value of the fiber component.” It particularly flushes fat calories from your body. (See section 5.3)
- As mentioned earlier, fiber increases SCFA production. An increase in SCFAs stimulates the production of a hormone called cholecystokinin (CCK). CCK increases a feeling of fullness and improves digestion.
Is Soluble Fiber Better Than Insoluble Fiber For Weight Loss?
There is no clear-cut evidence of which one of the above fibers is better for weight loss. A lot more research needs to be done to determine which is superior.
- “All in all, the improvement of obesity by DF (dietary fiber) mainly comes from the physicochemical properties such as WHC, WSC, OHC, CAC, and viscosity, which delay the absorption of fat from food. Both SDF (soluble fiber) and IDF (insoluble fiber) have the effects of reducing obesity, which is better requires a lot of experimental researches.” (See section 3.1)
These abbreviations might be nerve-racking, so let’s briefly discuss what each of these fiber properties means regarding weight loss. (Source at Section 2)
- WHC (water holding capacity) – fiber with high WHC can improve intestinal flow and swell your food after absorbing water. This will make you feel fuller with less food.
- WSC (water swelling capacity) – WSC helps reduce weight for the same reasons as WHC.
- OHC (oil holding capacity) – fiber high in OHC can absorb the fat from your food, reducing the intake of excess calories in the body. This can prevent you from gaining weight.
- CAC (cholesterol adsorption capacity) – fiber with good CAC can prevent and treat obesity by absorbing cholesterol and producing short-chain fatty acids (SCFAs). SCFAs are potent regulators of your metabolism and help prevent obesity.
- Viscosity – fiber with high viscosity can prevent obesity by delaying fat formation. It creates stickiness in the intestines that help reduce fat intake from foods. Higher viscosity fiber also slows down gastric-emptying (slows down your meal from getting digested), resulting in reduced appetite. (See section 6.3)
It has long been scientifically established that both soluble and insoluble fibers contribute to weight reduction. An older study from 2001 confirmed that “…the majority of studies indicate that an increase in either soluble or insoluble fiber intake increases postmeal satiety and decreases subsequent hunger.”
In a 45 week-long study on obesity-prone mice, the researchers fed the mice with both soluble and insoluble fiber to determine which worked better on obesity. The results showed that the soluble fiber caused a significant weight gain over the insoluble kind.
In an interesting human study, inulin, a soluble fiber component, was tested against cellulose, an insoluble fiber component, to determine which one was better for weight loss. The study lasted 18 weeks. At week 9, both groups saw a similar weight reduction, but at week 18, the inulin group lost more weight.
However, the study cautioned that the experiment may not have been “long-enough to measure true long-term weight loss maintenance” from both groups. It also stated that cellulose increases GLP-1 (appetite suppressant hormone) levels when taken for more than a year. In other words, cellulose may work better for weight loss in the long run.
Both types of fiber are essential to weight loss. And as far as the scientific community is concerned, one is not superior to the other.
Here Is How Soluble And Insoluble Fiber Contribute To Weight Loss
Soluble Fiber For Weight Loss
When digested and fermented in the colon, soluble fiber produces SCFAs. SCFAs are potent appetite regulators.
When the SCFAS increase in quantity, they stimulate the production of peptide YY (PYY) and glucagon-like peptide-1(GLP-1), two appetite suppressant hormones. (See section 6.5)
In essence, a diet rich in soluble fiber will help you lose weight because you will naturally eat less.
Insoluble Fiber For Weight Loss
The primary function of insoluble fiber (InF) is to help the food you eat move smoothly through your digestive system, soften stool, and make it easier to eliminate.
However, InF is not beneficial only for the elimination of stool but also for weight loss.
A study on rats demonstrated that InF could prevent obesity and reduce the damage caused by a high-fat diet.
Since InF is not digested or fermented like soluble fiber, it remains longer in your digestive system. It causes InF to interact with your gut bacteria for a more extended period.
The mechanism InF uses to combat weight gain is by manipulating two particular bacteria that cause weight gain.
Many studies have shown that people prone to being obese have fewer Bacteroidetes and more Firmicutes in their gut.
This study proved that InF increases Bacteroidetes and decreases Firmicutes, causing weight loss in rats fed a high-fat diet.
Also, it appears that InF is better than soluble fiber for weight loss if someone is consuming a high-fat diet. The researchers in this study clarified that because insoluble fiber speeds up the digestion and elimination of food, fewer calories enter your body, especially from fat sources.
InF appears to create an anti-nutritive effect – meaning that extra calories are eliminated before your body has a chance to digest them. This process will cause weight loss!
How Much Fiber To Eat Daily?
The general guidance for an adequate intake (AI) is 14 grams for every 1000 calories eaten. When applying the energy guideline of 2000 cal/day for women and 2600 cal/day for men, the recommended daily dietary fiber intake is 28 g/day for adult women and 36 g/day for adult men. (Source on page 3)
According to the Institute of Medicine, “the recommended Dietary Reference Intake (DRI) daily allowance” is: (2022 report)
- 25-38 g/day – for under 50 (14g/1,000 kcal/day)
- 38 g/day – men between 19-50
- 25 g/day – women between 19-50
- 31 g/day – men over 51
- 21 g/day – women over 51
- 19 g/day – children 1-3
- 25 g/day – children 4-8
- 31 g/day – boys 9-13
- 38 g/day – boys 14-18
- 26 g/day – girls 9-18
NOTE: Eating above the recommended AI can cause side effects, such as bloating, abdominal pain, gas, constipation, diarrhea, and loss of nutrients.
Fiber is excellent for weight loss. Studies show that both insoluble and soluble will help you lose weight, and as it stands now, one is not superior to the other.
Soluble fiber appears to help weight loss when fermented in the colon. Insoluble fiber, which cannot be fermented, passes indigested and is eliminated through stool, taking with it extra calories that your body would otherwise have digested.
The bottom line – both types of fiber assist in weight loss by using a different mechanism.
FIBER IS GOOD FOR WEIGHT LOSS!!!