How High Fiber Diet Is Linked To Weight Loss

Written by Dr. Adam Friedman
High-Fiber Diet

Fiber for Weight Loss

Today, I’m going to discuss the benefits of dietary fiber. WAIT! Don’t click away yet! I promise you’ll get something out of this.

First, the boring part: There are essentially two types of fiber – Soluble and insoluble. The short version goes; soluble fiber slows down gastric emptying while insoluble fiber decreases transit time from the intestinal tract. Allow me to elaborate:

When you consume soluble fiber (see below for examples) it holds the food you eat in the stomach longer, allowing the acid secreted by the stomach more time to break down the food into its constituent parts. This gives the small intestine more opportunity to absorb and assimilate that food, giving you more nutrition for your body.

How High Fiber Diet Keeps You Healthy?

Any foods that aren’t sufficiently broken down will simply pass through the gastrointestinal tract undigested, making it useless to your body. It also reduces the glycemic load of meals and slows down the absorption of carbohydrates, keeping blood sugar levels in check.

The other cool thing about soluble fiber is it feeds your good gut bacteria (AKA prebiotics). Yes, you have bacteria in your gut and lots of ‘em. You see, humans have more bacterial cells (most of which are in the intestines and skin) than host (human) cells. We have evolved over a very long time to cultivate a symbiotic relationship with these strains of bacteria and as such, we need to take care of them, so they take care of us. The soluble fiber, which we can’t break down and use ourselves, ferments and is “eaten” in the colon (large intestine) by the bacteria that help keep us healthy. It’s a win-win!

Fiber Keeps You Healthy

How do they keep us healthy? The short chain fatty acids that result from the fermentation of soluble fibers create such byproducts as butyrate, propionate, and acetate. Higher levels of butyrate, for example, have been proven to improve things such as insulin sensitivity, inflammation and Crohn’s symptoms.

Insulin sensitivity is an issue with low fiber diets for a couple reasons. First, if your tissues (muscles, organs, etc.) are less sensitive to insulin, the pancreas must secrete more insulin to get the glucose out of the blood and into the tissues. In the presence of insulin, lipolysis (fat burning for energy) will not take place. This is the tradeoff we have with this life-saving hormone. Without insulin we die. With too much insulin, we get (or stay) fat. So soluble fiber improves insulin sensitivity, allowing us to break down more fat for energy (the way we evolved).

Secondly, when we eat more fiber, we feel fuller. Hopefully, when you feel full, you stop eating (if you don’t, we need to have a different discussion). When you eat fewer carbs (sugars), you need less insulin to deal with those carbs. With less insulin present, more fat loss is possible. Now, I’m not saying just because you eat less food (overall) you’re going to lose weight (excess fat, to be exact). We would have to also to discuss the quality of the food you’re consuming, but we’ll leave that for another day.

Must Watch – Benefits of Fiber With Dr. Melissa Najarian: Essentia Health

Some examples of fermented foods are sauerkraut, kimchee, Greek yogurt, Kefir, Kombucha. All are good examples of wonderful fermented foods that will feed your good bacteria, and make your gut an unwelcome place for the bad bacteria to embed.

The second type of fiber, insoluble, is beneficial in other ways. Insoluble fiber speeds up the process of getting rid of the waste our bodies can’t utilize. It adds bulk to stool, softening the stool by absorbing more water, and allows for easier bowel movements, with less straining. This type of fiber has been shown to reduce the likelihood of becoming constipated.

How Much Fiber Does Your Body Need?

Much Fiber Does Your Body Need

Just how much fiber you need depends on your size and nutritional requirements. Unless you’ve already started to make changes in your diet, you’re probably going to be on the wrong end of the fiber spectrum. Start slowly. Add a few grams of fiber a day and taper up over the course of a couple weeks. Whether it’s an extra apple a day or two more servings of green leafy veggies, the important thing is to not ingest too much too soon. You don’t want to get bloated and gassy in the process.

Because everyone is different (size, nutrient requirements, gut microbiome, etc.) between 50 and 75 grams of carbohydrates from mostly vegetables and some fruits is a good start. Gradually work up to 100 grams per day. Include plants concentrated in prebiotic fiber, such as raw onion and garlic, leeks, Jerusalem artichokes, dandelion and green bananas. These should provide your gut ample nutrition, adequate filling (feeling satiated) and curb cravings for simpler carbs.

Food Serving
Total Fiber
Soluble fiber
fiber (grams)
Apple, with skin 1 medium 3.0 1.0 2.0
Banana 1 medium 2.0 0.6 1.4
Pear, with skin 1 medium 4.5 0.5 4.0
Orange 1 medium 2.0 1.3 0.7
Prunes ¼ cup 3.0 1.5 1.5
Strawberries ½ cup 1.0 0 1.0
Carrots 1 large 2.9 1.3 1.6
Broccoli ½ cup 2.7 1.3 1.4
Brussel sprouts, cooked ½ cup 4.5 3.0 1.5
Corn ½ cup 1.5 0 1.5
Potato, baked with skin 1 medium 4.0 1.0 3.0
Spinach ½ cup 2.0 0.5 1.5
Black beans, cooked ½ cup 5.5 2.0 3.5
Garbanzo beans, cooked ½ cup 6.0 1.0 5.0
Green peas, cooked 2/3 cup 3.9 0.6 3.3
Kidney beans, cooked ½ cup 6.5 1.6 4.9
Lentils, cooked 2/3 cup 4.5 0.6 3.9
Lima beans, cooked ½ cup 6.5 3.5 3.0
Pinto beans, cooked ½ cup 5.9 1.2 4.7
Peanut butter, chunky 2 tbsp 1.5 0 1.5
Psyllium seeds, ground 1 tbsp 6.0 5.0 1.0
Barley, cooked ½ cup 4.0 1.0 3.0
Bran flake cereal ¾ cup 5.5 0.5 5.0
Brown rice, cooked ½ cup 1.5 0 1.5
English muffin, whole
1 4.0 1.0 3.0
Rolled oats, cooked ¾ cup 3.0 1.3 1.7
Whole-wheat bread 1 slice 2.5 0.5 2.0

Contributor : Dr. Adam Friedman (Consumer Health Digest)

This Article Has Been Published on March 31, 2015 and Last Modified on October 4, 2018

Dr. Adam Friedman graduated from Bastyr University Doctorate of Naturopathic Medicine program. He is now a Licensed Naturopathic, Neuro-Cranical Restructuring Practitioner, and Massage therapist- Specialized in physical Medicine and Rehabilitation. He holds a Master's degree in exercise physiology along with dual bachelor's degree in pre-Physical therapy and psychology. From over 20 years, Dr. Friedman has vast experience in the health and wellness field. He has been certified as a Strength and Conditioning Specialist through the National Strength and Conditioning Association and has completed the Cross Fit Level One Trainer Course. Connect with him: LinkedIn or visit his website.

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