Carbohydrates to Avoid on GAPS: Sugars, Starch and Foods

GAPS separates carbohydrates by the work needed to digest them. Dr. Natasha Campbell-McBride uses the difference between single sugars, double sugars and starch to explain why grains, table sugar and starchy vegetables leave the diet while other carbohydrate foods remain. The food list and preparation rules still matter; molecule size alone is not a shortcut for deciding whether a food fits.^[1]

Before our family started GAPS in July 2024, we ate a lot of sugar and processed carbohydrates and drank Gatorade. Changing those everyday foods was part of the larger change in our kitchen. This guide explains the carbohydrate reasoning behind it. Keep the complete foods-to-avoid guide alongside it for the wider ingredient list.

The Three Carbohydrate Groups

In Campbell-McBride’s explanation, single sugars can pass through the gut lining without first being split into smaller sugars. She names ripe fruit, vegetables, honey and soured milk products as food sources. That is different from saying every one of those foods can be eaten immediately, in any form or amount.^[1]

Why Double Sugars Need More Digestion

Double sugars must be split into single sugars before absorption. The book describes enzymes called disaccharidases on the brush border, the tiny projections on the intestinal lining’s cells, as doing that job. It connects impaired enzyme production with undigested sugars remaining available to abnormal gut flora.^[1]

Sucrose is table sugar, lactose is milk sugar, and maltose is produced during starch digestion. Campbell-McBride describes undigested double sugars feeding pathogenic bacteria, Candida and other microbes and contributing to further gut damage. She also discusses enzyme deficiencies in chronic conditions without obvious digestive symptoms, including rheumatoid arthritis and multiple sclerosis. This is the GAPS explanation for removing double sugars while the gut recovers.^[1]

Why Starch Is Treated Differently

Starch contains many single sugars linked into long, branching molecules. The book identifies grains, most legumes and certain root vegetables as major sources. It explains that starch digestion produces maltose, which then needs the same brush-border splitting step as other double sugars.^[1]

Campbell-McBride therefore removes grains, starchy legumes and starchy vegetables during GAPS. Her discussion also says that many people can eventually reintroduce grains and starchy vegetables after sufficient digestive recovery. The food list and phase map help separate the active diet from that later transition.^[1]

The Food Groups Removed

Grains and Products Made From Them

The book’s group includes wheat, rye, rice, oats, corn, sorghum, barley, buckwheat, millet, spelt, triticale, bulgur, tapioca, quinoa and couscous. It acknowledges that some are not technically grains. Gluten-free does not remove this carbohydrate rule: a flour can have no gluten and still be made from an excluded starch.^[2]

Starchy Vegetables

The named group includes potato, yams, sweet potato, parsnip, Jerusalem artichoke, cassava, arrowroot and taro, including products made from them. It is separate from the book’s non-starch vegetable list. Our sweet potato guide explains that example and the squash substitute named in the official FAQ.^[2]

Table Sugar and Foods Containing It

The rule covers table sugar and foods made with it, including processed products where sugar is one ingredient among many. Honey has a different place because it is largely glucose and fructose, but its use still follows the diet’s timing and amounts. The honey guide covers that distinction without making honey an unlimited substitute.^[1][2]

Starchy Beans, Legumes and Pulses

The book names soybeans, mung beans, garbanzo beans or chickpeas, bean sprouts, faba beans and other starchy varieties among the exclusions. It also allows particular legumes when properly prepared and introduced after sufficient digestive recovery. For many people, its general discussion says this can mean avoiding legumes for a year or longer.^[2]

The allowed ordinary varieties and the book’s separate double-fermentation preparation need their own explanation. Our beans and legumes guide keeps those permissions and methods together. An ordinary soak, a single ferment and the complete double-fermentation method are not interchangeable.^[3]

Lactose and Fermented Dairy

Lactose belongs to the double-sugar group. The book places fluid or dried milk and processed foods containing lactose outside the diet and explains why homemade fermented dairy has a different role.^[2]

Its official FAQ adds that some lactose remains in fermented dairy, even aged cheese, and that the amount varies between batches. Longer fermentation may reduce it further for particularly sensitive people. Fermentation is not a guarantee of a zero-lactose result. Our milk and dairy guide explains the preparation and sourcing details, while the dairy introduction guide gives the separate sequence.^[4]

What This Means at Your Table

The book acknowledges that ripe fruit and non-starch vegetables contain small amounts of sucrose or starch. It considers these amounts much smaller than those in grains, starchy vegetables and table sugar, and says most people can cope with them. That is why the actual food list matters more than trying to remove every trace of starch or sugar from every ingredient.^[1]

Preparation and stage still apply. A cooked vegetable, a raw salad and a fermented vegetable are different forms. Ripe fruit, honey, legumes and fermented dairy also have their own introduction guidance. Use the vegetable guide and fruit guide for those details.

Frequently Asked Questions

Does GAPS Remove All Carbohydrates?

No. The book keeps carbohydrate foods such as suitable vegetables, ripe fruit, honey and fermented dairy within their preparation and introduction rules. Its distinction concerns digestion and food type, not a universal instruction to eat no carbohydrates.^[1]

Is Ripe Fruit Suitable for Everyone Immediately?

No. Besides Intro timing, the official FAQ gives a specific initial exception for diagnosed fructose malabsorption: fruit and honey may need to be avoided at first and reintroduced as the person progresses. The presence of a single sugar does not remove every individual food consideration.^[5]

Can These Foods Return After GAPS?

The book describes later reintroduction after digestive recovery. That is a separate decision from whether a food belongs in the current Intro or Full GAPS phase; it is not an automatic permission once a certain number of months has passed.^[1]

Your Next Step

Choose one meal you already make and identify where its grain, sugar or starch comes from. Then use the food list to choose an ingredient that fits the same cooking job and your current phase. The GAPS Food Swap Guide is listed in the WFLI Shop for shopping, label reading and practical family swaps.

References

1. Campbell-McBride, Natasha. Gut and Physiology Syndrome (2020), “Carbohydrates,” single sugars, double sugars, starch and the small amounts in fruit and vegetables.
2. Campbell-McBride, Natasha. Gut and Physiology Syndrome (2020), “To Summarise,” excluded food groups and the lactose rule.
3. Campbell-McBride, Natasha. Gut and Physiology Syndrome (2020), “Beans, Legumes and Pulses,” and “Double-Fermented Beans,” preparation-dependent permissions.
4. Dr. Natasha Campbell-McBride’s official FAQs, Dairy, Question 9, lactose remaining after fermentation.
5. Dr. Natasha Campbell-McBride’s official FAQs, Diet/Food, Question 37, diagnosed fructose malabsorption.