Let’s take a quick look at the research and how much fiber is necessary for weight loss. Then we'll discuss where to get your fiber and which types do what.
Less fiber intake linked with obesity
First let’s look at some evidence showing that eating less fiber is linked to obesity.
A 2017 study from Spain’s Madrid Complutense University tested 1,655 adults. Each study participant underwent an examination and recorded their typical diet for three days. The foods eaten by each participant were converted and computed for their dietary fiber content.
The doctors statistically compared the average daily fiber intake with each subject’s body mass index. This determined whether there was a correlation between fiber consumption and relative weight.
The researchers found those who were obese ate less fiber than those who were not obese. And overweight people ate less fiber than those who were in the healthy weight category.
The researchers found those with normal weight ate an average of 13.4 grams of fiber per day. Those who were obese ate an average of 11.83 grams. Those who were overweight but not obese ate an average of 12.22 grams of fiber per day. Far less than the minimum recommendation of 20-25 grams of dietary fiber per day (optimum is 25-35 grams/day).
Furthermore, those who consumed more fiber in their snacking had less abdominal obesity and less excess body weight.
Supplementing with fiber sheds pounds
It’s one thing to link dietary fiber intake and obesity. But it’s another to actually show that people lose weight when they supplement with fiber.
A number of recent studies have shown that supplementing with fiber results in weight loss.
In a 2017 study from the University of Illinois, researchers conducted a meta-analysis of 12 clinical studies that included 609 people. These studies lasted from two weeks to 17 weeks of fiber supplementation.
The researchers found that supplementing with fiber reduced weight by an average of body mass index by an average of 0.84 points, and over 5-1/2 pounds. Remember, this is from supplementing with fiber for between two and 17 weeks.
Furthermore, the research found that the fiber supplementation reduced body fat and fasting insulin levels – the latter by an average of 15.88 pmo/L.
Another 2017 study from Curtin University in Australia studied 118 overweight adults. This study supplemented a fiber supplement for 12 weeks, with a placebo given to a control group.
The researchers found that the fiber supplement reduced body weight by an average of a little over 3 lbs (1.52 kilograms) and an average reduction in BMI by 0.5. The supplement also reduced the number of eating times by an average of 1.4 per person.
A 2013 study using the same fiber supplement studied 52 adults, of which 49 were women. This study found that over a 12-week supplementation period, the group lost an average of 10.33 lbs (4.69 kilograms).
The latter study also found the subjects experienced average reductions in waist circumference by 7.11 centimeters and 5.59 centimeters in average hip circumference reduction.
High-fiber high-carb diet reduces weight
Maximizing our fiber intake in our diet typically means increasing our carbohydrate levels. But high-fiber carbs are not like the carbs that most frown on – like sugary foods and empty refined junk foods.
A healthy high-carbohydrate diet means whole grains, whole fruits and vegetables, and whole nuts and seeds.
Proving this point, researchers from medical schools from Harvard, the University of Texas, the University of Washington, George Washington University and others conducted a 2017 study on 3,234 adult volunteers. The subjects had a high risk of diabetes, but were not diabetic.
For one year, the researchers had the participants follow one of three different diet plans, with one acting as a control group.
The researchers found those that ate a high-fiber, high-carbohydrate diet lost the most weight over the year. They found that for every five additional grams of fiber per day in their diet resulted in the loss of 1.10 lbs over the year.
This means that a person who eats, say 20 grams of fiber per day should see a loss of over four pounds. Better yet, eating what naturopaths typically recommend – around 30 grams of fiber per day – should result in dropping over six pounds in a year on average. Of course, this is specific to those who need to drop weight and dependent upon other factors. Some may see more or less results from a high-fiber diet. Other diet factors, increased exercise and greater water consumption also make a difference.
Speaking of other diet factors, the researchers also found that those who ate less total fat and saturated fat also saw their weight drop. And those who ate more fat in their diets experienced weight gain.
The researchers – remember, from major medical schools – concluded:
“Higher carbohydrate consumption among DPP [Diabetes Prevention Program] participants, specifically high-fiber carbohydrates, and lower total and saturated fat intake best predicted weight loss when adjusted for changes in calorie intake. Our results support the benefits of a high-carbohydrate, high-fiber, low-fat diet in the context of overall calorie reduction leading to weight loss, which may prevent diabetes in high-risk individuals.”
These results are consistent with a number of smaller studies that have found that increased consumption of whole grains resulted in weight loss.
For example, a 2017 study from the USDA Human Nutrition Research Center and the University of Minnesota studied 81 men and women who were between 40 and 65 years old.
The researchers increased the patients’ consumption of either whole grain with fiber or refined grains with less fiber for a period of 6 weeks.
The researchers found metabolic changes among the whole grain group that were consistent with weight loss. They concluded:
“These findings suggest positive effects of whole grains on the resting metabolic rate and stool energy excretion that favorably influence energy balance and may help explain epidemiologic associations between whole-grain consumption and reduced body weight and adiposity.”
Gut probiotics explains part of the relationship
One of the critical relationships between fiber and weight loss is the activity of probiotics. Dietary fiber in effect feeds our gut probiotics. Probiotics help reduce weight. And as I showed in my book on the topic, gut probiotics help us reduce inflammation and the risk of colon cancer.
A number of studies have confirmed this effect. Let’s look at just one of them. In a 2017 study from the University of Calgary, researchers tested 42 kids between 7 and 12 years old. The researchers gave one group 8 grams an inulin fiber (prebiotic) supplement each day for 4 months. The other group a placebo for the same period.
The researchers found that the children given the prebiotic fiber supplement lost an average of 3.1 percent body weight. These kids also lost an average of 2.4 percent body fat and 3.8 percent loss in “trunk fat” during that period.
The prebiotic fiber group also experienced a 19 percent average drop in triglycerides and a 15 percent decrease in inflammation marker interleukin-6.
When the researchers tested their gut probiotics, the prebiotic fiber group of kids had significant increases in Bifidobacteria probiotics and reduced levels of pathogenic bacteria.
Weight loss may be a lot easier than you thought
Most of the research discussed above also saw an important side effect of eating more fiber: They found that supplemented fiber and higher fiber diets resulted in more satiation. Satiation is that feeling of fullness – a feedback signal telling your brain that you’ve had enough to eat.
When we feel full earlier, we eat less. Simple as that. This means that the weight loss from increased fiber consumption can continue long after the periods investigated in the research. Because as common sense and practical evidence have always shown us, eating less naturally helps us drop the weight.
Furthermore, when we eat more fiber in our diet, we also enjoy benefits associated with a lower risk of inflammation and heart disease.
The latter was evidenced by a large 2017 review of research from the National University of Health Sciences in Lombard, Ill. This study analyzed 31 meta-analyses of previous clinical research and found that fiber supplementation or increased fiber in the diet reduced the risk of cardiovascular disease and death from heart attacks by around 20 percent.
The study also found that higher fiber intake or fiber supplementation resulted in better cholesterol levels.
Fiber choices
As mentioned above, naturopaths typically recommend between 25 and 35 grams of dietary fiber each day, combined between soluble and insoluble. A typical natural high-fiber diet will contain about three-to-one (3:1) insoluble to soluble fiber.
What’s the difference between soluble and insoluble fiber, you ask?
Insoluble fiber is not water soluble. It is naturally found in whole grains, bran and vegetables. This type of fiber bulks up our foods, increases the passage of food through the intestines, and increases bowel movements.
In other words, insoluble fiber reduces and helps prevent constipation and helps remove toxins from the colon. Cellulose, hemicellulose and lignans are all insoluble, and these are contained in all plant-based foods.
Soluble fiber is water soluble. It actually slows digestion a little but helps control cholesterol and feeds our probiotics. This type of fiber is thus great for gut health. Foods that contain soluble fiber include barley, oats, peas, beans, seeds, nuts, fruits, vegetables and psyllium husk.
What about supplementing fiber?
By far the best approach is to get your fiber from natural whole foods. This means whole grains, vegetables and fruits. Make choices such as:
• Brown rice instead of white rice
• Whole wheat bread instead of white bread
• Whole wheat pasta instead of regular pasta
• Whole oatmeal or granola for breakfast instead of bacon and eggs
• Whole wheat pizza dough instead of regular pizza dough
• Fresh or steamed vegetables instead of overcooked can versions
• Fresh fruits instead of fruit juices
Anyway, you get the idea. Typically, convenient foods have had the fiber removed from those ingredients. The result is a smoother mouthfeel, but less fiber.
Supplementing insoluble fiber:
If you have constipation, then supplementing your insoluble fiber is a great strategy. But be careful because your digestive system can become dependent on this if you do this too much. You can choose natural supplements such as cellulose fiber.
Supplementing soluble fiber:
Supplementing soluble fiber to increase your fiber intake is a great way to increase dietary fiber. But use natural fibers to maintain a good balance between soluble and insoluble. And if your digestive tract is more sensitive, be careful with inulin because some people are sensitive to inulin. Here is a quick list of natural soluble fiber supplement types:
• Inulin oligofructose (chicory root, beets, onions)
• Psyllium husk (Plantago plants)
• Pectin (apples and other fruits and vegetables)
• Glucomannan (Konjak plant fiber)
• Resistant starch (from whole grains)
• Wheat dextrin (wheat)
• Oat bran
• Rice bran
Of course, there are other fiber supplements that are synthetic (such as polydextrose) or those synthesized from natural products such as wood fiber (such as methylcellulose). These may work well for temporarily increasing fiber intake and helping reduce weight. But they may also come with side effects over time. One possibility is that your digestive tract may become dependent upon them for regularity.
While synthetic dietary fiber supplements may not come with side effects, they just have that unknown factor of not being part of our historical diet.
It is easy to find natural whole food type supplements, such as oat bran or psyllium. Oat bran is separated from the whole oat, and contains both soluble and insoluble fiber. This makes oat bran one of the best well-rounded fiber supplements. Psyllium contains 70 percent soluble fiber.
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