Can You Get Enough Fiber on a Low Carb Diet?

Two different conditions with two conflicting dietary prescriptions. Nutrition Diva helps make sense of seemingly contradictory advice.

Monica Reinagel, MS, LD/N, CNS
4-minute read
Episode #419

Christy writes:

“I need your expertise! I am overweight and suffer from polycystic ovarian syndrome (PCOS). For that, I’m told to follow a low-carb diet. But I also have mildly elevated cholesterol and a familial tendency toward fatty liver disease. For that, I’m told to eat lots of fiber and whole grains, which are loaded with carbs. So what should I do?”

Maybe you’ve found yourself in a dilemma similar to Christy's, where dietary recommendations for one health concern directly conflict with dietary advice for another. For example, I remember getting an email a few years back from a woman who had both IBS and diverticulosis and was wondering about her doctor’s advice to eat a high-fiber diet. While that can certainly help with diverticulosis, it can make IBS worse!

See also: Should I Eat a High Fiber or Low Fiber Diet for Diverticulitis?

In some cases, your best bet may be to work with a nutrition professional, who can not only help you sort through and reconcile conflicting recommendations but can also help you translate them into practical solutions such as meal plans and shopping lists.

That was definitely the case for the woman with IBS and diverticulosis and it might also be a good idea for Christy. In the meantime, however, I think I can help resolve Christy’s dilemma—because the recommendations to increase fiber and decrease carbohydrates are not as contradictory as you might think.

Why Is Low Carb Better for PCOS?

Let’s start by taking a closer look at the idea that people with PCOS need a low carb diet. As I talked about in a previous episode on PCOS, people with this condition are likely to have some degree of insulin resistance, meaning that they have trouble managing their blood sugar. Going on a strict low carbohydrate diet is one way to deal with insulin resistance but it’s not the only way.

I prefer a less drastic approach, where we focus on reducing the carbs that are doing the most damage (and contributing the least nutrition) but avoid throwing the baby out with the bathwater.

First, you’d want to eliminate sweetened beverages, fruit juice, candies, pastries, desserts and other things made with sugar and white flour. These are high glycemic carbohydrates, meaning that they are quickly digested and absorbed into the bloodstream. Eating a lot of high glycemic carbs when you have insulin resistance or blood sugar issues is like pouring gasoline on a fire.

See also: What is High Glucose?

Other, more nutritious sources of carbohydrates, such as whole fruit, dairy products, legumes, and whole grains aren’t high glycemic foods--but they’re not low glycemic either.  They can certainly be included in your diet. The trick is to consume them in moderation. So, for example, while whole grains are a better choice than refined grains, you still might limit your consumption of whole grain foods to just a couple of servings per day. 

Non-starchy vegetables are almost 100% carbohydrate—but these are very low glycemic carbs (not to mention nutritional superstars) No need to limit them.

Just to review: You’re going to largely eliminate high glycemic carbohydrates like sweetened beverages, desserts, white bread and other things made with white flour. You’re going to moderate your intake of moderate glycemic carbohydrates like whole fruit, dairy, legumes, and whole grain foods. And you’re going to load up on low glycemic carbohydrates.like non-starchy vegetables. So far, so good.


About the Author

Monica Reinagel, MS, LD/N, CNS

Monica Reinagel is a board-certified licensed nutritionist, author, and the creator of one of iTunes' most highly ranked health and fitness podcasts. Her advice is regularly featured on the TODAY show, Dr. Oz, NPR, and in the nation's leading newspapers, magazines, and websites. Do you have a nutrition question? Call the Nutrition Diva listener line at 443-961-6206. Your question could be featured on the show.