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As is always the case on Meridian, the opinions expressed in this article are the author’s and do not necessarily represent the views of this publication. 

This article is part of a series on the Word of Wisdom. To view all the articles in this series, see Discovering the Word of Wisdom.

Last week in Meat and the Microbiome, I explored the negative impact animal foods have on our microbiome. If you’ve missed any of the articles I’ve done so far on the human microbiome, here are the previous titles:

So far in this series on the microbiome, we’ve seen a consistency in the data that describes the central role diet plays in nourishing a healthy microbiota. In short, a diet of fiber-rich whole plant foods (fruits, vegetables, grains, and legumes) is critical to building and maintaining a healthy microbiome. The Western diet, filled with sugar, processed foods, and animal foods, has greatly (perhaps even permanently) compromised our gut flora and contributed to skyrocketing rates of allergies, food intolerances, autoimmune diseases, gastrointestinal conditions, and obesity.[1]

Given the clear consensus of the role of fiber in nourishing a healthy microbiome, it is surprising that many low-carb (low-carbohydrate) experts are particularly fond of stating that the human need for carbohydrates is zero. If this were true, the human need for fiber is also zero since fiber is a carbohydrate. Low-carb experts claim the human body is capable of surviving on fat and protein alone and that carbohydrates are completely unnecessary. Let’s remember: fat and protein are code words for “animal foods,” since animal foods are the primary source of fat and protein in our diets. The word carbohydrate, on the other hand, is a code word for plants, since plants (which also contain fat and protein) are the exclusive source of carbohydrates in our diet. (With minor exceptions, animal foods are completely devoid of carbohydrates.)[2]

The claim some low-carb experts make that there is no human need for carbohydrates is false, but like most falsehoods, it contains a grain of truth. That grain of truth is found in the Word of Wisdom. Speaking of animal flesh, the Lord states:

And it is pleasing unto me that they [animal flesh] should not be used, only in times of winter, or of cold, or famine. . . . And these [animals] hath God made for the use of man only in times of famine and excess of hunger. (D&C 89:13, 15)

Our Heavenly Father designed our bodies so that in times of need (winter, cold, famine, and excess of hunger), we can be sustained on the flesh of animals. This is clearly a tender mercy from the Lord, for surely there have been times when without the flesh of animals humans would have starved. We can think of Lehi and his family travelling to the Promised Land or some of the Mormon Pioneers crossing the plains. We can also think of small populations of people in particularly harsh environments, like the Eskimos.

It is easy to see why isolated people in extenuating circumstances relied heavily on animal foods for their diets, but what is puzzling is the modern phenomenon of wildly popular low-carb diets. What is behind this popularity? Is it the short-term benefits some experience when first starting to eat this way?

It is true that there are plenty of examples of people losing weight on these diets and even resolving certain health problems. So why be concerned? Since our bodies are able get nutrients from animal foods, what is wrong with going low-carb (especially if it is only temporary) in order to lose weight or resolve some health issue?

Gut Reactions to a Low-Carb Diet

Consider again what the concept of “low carb” means. Carbohydrates come exclusively from plants, so low carb, means “low plant foods.” It especially limits those foods that provide a significant amount of complex carbohydrates: grains, legumes, potatoes, corn, etc. But it often reduces or eliminates many types of fruits and vegetables, particularly those high in complex carbohydrates or starch.

Can the human body temporarily get by with few or none of the wholesome plants the Lord ordained for our “constitution, nature, and use” (D&C 89:10)? Yes, and this is a tender mercy.

But what about our microbiome? What about the healthy bacteria that live in our guts and are vital to the functioning of the entire human body? Can these friendly bacteria survive, even temporarily, on a diet devoid of carbohydrates? No. A low-carb diet is a death sentence for many of our ancient friends, the microbes that rely on the dietary fiber in carbohydrates for their very existence.

While we humans can survive on a high animal food diet, this situation is extremely rare in the history of humankind. Our ancestors, with few exceptions, lived on diets high in whole plant foods. Current estimates suggest our distant ancestors consumed roughly 150 grams of fiber per day.[1] Compare that with an average of roughly 15 grams of fiber in the modern American diet, and it gives you some sense as to how our diets have changed. This is a 10-fold decrease in this nutrient that is essential to healthy gut flora. This is compounded by lifestyle changes, like the overuse of antibiotics, which also threaten our microbiota. What is the gut’s reaction to this modern lifestyle and low fiber diet?

  • Modern humans appear to have lost roughly one-third of the diversity of microbial species that our distinct ancestors are likely to have had.
  • The number of healthy bacteria (which ferment wholesome plant foods) has dramatically declined in our guts, while the number of relatively non-beneficial bacteria (that thrive on a fat and protein diet) has gone up.
  • It appears that some of the diminished quality of our microbiome may be a permanent loss.[3]

The modern Western diet is already low in complex carbohydrates. What then happens when we go on a “low-carb” diet and remove even more plant foods and add even more animal foods? We generally lose weight because our body assumes we are in a time of great need (think: extreme cold, famine, hunger) and goes into emergency mode, otherwise known as sickness.[4] Losing weight may even lead to other positive health results, but because the human body is designed to run on carbohydrates as its primary fuel, the long-term consequences are disastrous.

Low carbohydrate diets lead to dysbiosis, a state of microbial imbalance.[1] Our gut bacteria are central to our digestion, metabolism, immune system, and central nervous system, so a diet that does not nourish our microbiome can lead to malfunctions in the very biological processes our gut bacteria perform for us. No wonder the chronic diseases related to dysbiosis have steadily risen with the popularity of low-carb diets.

What Low-Carb Experts Say

Comparing what low-carb experts say about nurturing a healthy microbiome with what the experts on the microbiome are telling us is an eye-opening experience. For example, low-carb expert Daniel Perlmutter, author of Grain Brain, wrote a whole book on this topic: Brain Maker: The Power of Gut Microbes to Heal and Protect Your Brain—For Life.[5] But don’t expect to learn about a diet in harmony with either the Word of Wisdom or a healthy microbiome by reading this book. While it is not devoid of information, it also contains many half-truths and inaccuracies.

In his book Dr. Perlmutter consistently emphasizes that the food we eat is “the most significant factor related to the health and diversity of the microbiome” (p. 12). He correctly extols the importance of “foods that are high in fiber, which provide fuel to the gut bacteria,” a point he says he “can’t reiterate . . . enough” (p. 60). He also correctly identifies a high fiber diet as essential to supporting

a robust mélange of bacterial species, which helps maintain the integrity of the gut wall, keep blood sugar in check, reduce inflammation, and manufacture all those important substances and molecules critical for brain health and function. (p. 60)

But at the same time Perlmutter insists that a healthy diet must be low in carbohydrates. In fact, he is one of the many low-carb proponents who insist that “the human requirement for dietary carbohydrate is none, none whatsoever.”[6] But what he doesn’t explain is that fiber is a carbohydrate. A diet low in carbohydrates is low in fiber. A diet with no carbohydrates has no fiber. This confusion over carbohydrates and the very food beneficial bacteria require to survive is at the heart of the problem with this way of eating.

Where the science shows the biggest threat to our microbiome comes from a low-fiber animal and processed food diet, Perlmutter attacks what he calls “gut-blasting, microbiome-damaging gluten” (a protein in wheat) as the primary enemy of the gut (p. 149). This is a complete contradiction of the scientific evidence that the fiber in whole wheat is one of the best sources of fiber for our gut bacteria. In fact, many of the scientific studies Perlmutter cites in his book actually include wheat as a healthy source of food for our gut bacteria.[7]

An Unhealthy Recipe for the Microbiome

What is Dr. Perlmutter’s recipe for a healthy microbiome? It is to reduce carbohydrates, the only source of the fiber desperately needed by our healthy gut bacteria, and increase “high-quality fats” (p. 184), which do nothing to nourish our microbiome. He calls his diet “high fiber” because it includes lots of fruits and vegetables; however, wheat, barley, and rye are totally excluded. Other high fiber grains and legumes are also discouraged or only allowed in very limited quantities. Thus, the very foods that currently supply the vast majority of fiber in the world’s food supply are either blacklisted or severely restricted.

Given the foods he recommends, it should not be surprising that Perlmutter encourages readers to shoot for a mere “12 grams” of fiber a day (p. 195), even while acknowledging that our ancient ancestors appear to have consumed more than 100 grams a day (p. 194). Even the USDA’s guidelines, which were set well before current research established the necessity of a high fiber diet for our microbiome, recommends at least 25-38 grams day.[8]

Even at just 12 grams a day, Dr. Perlmutter acknowledges that readers on the type of diet he recommends may have a hard time reaching that number and therefore may want to consider fiber supplements. Unfortunately, supplements have not proven to have the same beneficial effects on the microbiome as do healthy whole plant foods.[1] The type of low-carb diet Perlmutter advocates also appears to have many nutrient deficiencies by his standards, as he also recommends a long list of other dietary supplements to make up for these deficiencies (see Chapter 9 of Brain Maker, “Go Pro: The Guide to Supplements”). On his website, he tells us that he himself starts the day with a lengthy list of supplements.[9]

A More Excellent Way

Low-carb diets are low in the very food our microbiome needs to be healthy and perform its vital functions. Even if it results in short-term weight loss, why eat a diet that harms our microbiome when this can lead to allergies, food intolerances, autoimmune diseases, gastrointestinal conditions, and other serious diseases that can last a lifetime?

Yes, anyone can lose weight on a low-carb diet, but the price you may be paying is far too high! Eating the Word of Wisdom way nourishes both your body and your gut bacteria. It allows you to safely lose all excess weight, prevent and potentially resolve a long list of health issues, and comes with the Lord’s promise of amazing blessings (see D&C 89:18–21).

The world may continue to be enthusiastic supporters of low-carb diets, but I hope we Latter-day Saints will turn to the Word of Wisdom to find a more excellent way.

Feeding Your Microbiome a Healthy Word of Wisdom Diet

For help getting started on a healthy Word of Wisdom diet, both for yourself and for your microbiome, see: “Getting Started.”

Don’t forget that if you have not been consuming a high fiber diet, it can take some time for your microbiome to adjust to increased fiber. Here are some tips for adjusting to a higher fiber diet.

Jane Birch is the author of Discovering the Word of Wisdom: Surprising Insights from a Whole Food, Plant-based Perspective and many articles on the Word of Wisdom. She can be contacted on her website, Discovering the Word of Wisdom. Watch the video “Discovering the Word of Wisdom: A Short Film.”



[1] Justin Sonnenburg and Erica Sonnenburg, The Good Gut: Taking Control of Your Weight, Your Mood, and Your Long-term Health (New York: Penguin, 2015).

[2] There is a whole movement of people living a “zero carb” lifestyle. See: “Eat Meat. Drink Water: Zen, and the Art of Zero-Carb Living.” As stated on this site, “The term ‘Zero Carb’ is a bit of a misnomer because there is a small amount of carbohydrate in the form of glycogen in some animal foods such as egg yolks and liver. Cream also has about 1 gram of carbohydrate per ounce and can be problematic for individuals who are very sensitive to carbohydrates. A more accurate way to describe this way of eating would be to call it a ‘Zero Plant Foods’ diet.”

[3] Jane Birch, “Discovering the Word of Wisdom: Let’s Save Our Microbial Heritage!” Meridian Magazine (February 8, 2016).

[4] Low carb diets are, as Dr. John McDougall describes them “make yourself sick diets.” In this metabolic state of sickness, the body quickly uses up its store of carbohydrates (which accounts for the initial loss of weight) and then is forced to switch to using fat for calories. This state of sickness induces a loss of appetite so we are consuming less food and saving energy to weather the storm. See John McDougall, “High Protein Diets.”

[5] Daniel Perlmutter with Kristen Loberg, Brian Maker: The Power of Gut Microbes to Heal and Protect Your Brian—For Life (New York: Little, Brown and Company, 2015).

[6] Daniel Perlmutter, “Frequently Asked Questions,” “[Question] How much carbohydrate do we absolutely require in the diet? [Answer] While we definitely require protein and fat, the human requirement for dietary carbohydrate is none, none whatsoever.”

[7] One example of a reference Perlmutter uses that cites wheat as a healthy source of fiber for the microbiome: Joanne Slavin, “Fiber and prebiotics: Mechanisms and health benefits,” Nutrients, 5(4) (April 22, 2013): 1417-1435.

[8] USDA DRI Tables, “Dietary Reference Intakes: Macronutrients,” (2002/2005).

[9] Daniel Perlmutter, “Starting the Day with Supplements,”