Understanding Carbohydrates Part 2: Types, Tolerance, and How to Build Balanced Meals

Hi I’m Sammy, 

Your Good Farm in-house nutritionist.

Here to bring you essential information on nutrition, diet and permaculture gardening - in a bite size, easy to understand, science-backed way.

Hope you all had a festive and happy Christmas. I'm back now with Part 2: Types, Tolerance, and How to Build Balanced Meals!

Carbohydrates have been part of the human diet for thousands of years, but the way we grow, process, and consume them has changed dramatically. Their effect on the body depends on quantity, structure, fibre content, preparation, and the metabolic and digestive health of the person consuming them. Carbohydrates can be divided into sugars, starches, and fibre, each interacting differently with digestion, blood glucose, hormones, and the gut microbiome.

Sugars: Fast Fuel with a Narrow Use Case

Sugars are rapidly absorbed, making them useful in specific situations, such as during or immediately after intense physical activity. Outside of these contexts, frequent intake can increase insulin demand, contribute to energy crashes, cravings, inflammation, and reduced metabolic flexibility.

Importantly, “no added sugar” does not automatically mean a low blood sugar impact. Many foods perceived as healthy, such as breakfast cereals, are quickly broken down into glucose once digested. For example, rolled or instant oats digest rapidly due to processing, while oat groats, the intact whole form, release glucose more slowly. Similarly, foods like Cornflakes or Weet-Bix, despite containing little or no added sugar, are finely processed and metabolically behave more like sugars.

Health Insight: Structure Matters More Than Labels
Carbohydrate tolerance is influenced less by whether sugar is “added” and more by food structure, fibre content, preparation, and individual metabolic health. Whole fruit, when eaten intact, is generally well tolerated because fibre and plant compounds slow sugar absorption, unlike concentrated forms such as juice.

Starches: Starchy vs Non-Starchy Carbohydrates

Starchy and non-starchy vegetables differ in glucose impact and nutrient density.

Starchy Carbohydrates

• Definition: Contain higher amounts of digestible starch, contributing more glucose per serving
• Examples: Potatoes, sweet potatoes, corn, peas, winter squash, rice, oats
• Effects: Provide micronutrients, energy, especially for active individuals, but refined or excessive intake can cause rapid blood sugar rises

Health Insight: Pairing Matters
The glucose response to starches is influenced by what they are eaten with. Pairing starches with protein, healthy fats, fibre, or acidic foods slows digestion and moderates the glucose rise. Protein and fats delay gastric emptying, fibre slows enzymatic breakdown, and acidic elements (vinegar or lemon juice) reduce the speed at which starch is converted to glucose. For example, hot chips with vinegar spike glucose less than plain chips.

Non-Starchy Vegetables

• Definition: Lower in digestible carbohydrates, higher in fibre and micronutrients
• Examples: Leafy greens, broccoli, zucchini, cauliflower, peppers, cucumbers
• Effects: Provide micronutrients with minimal impact on blood sugar; often form the bulk of vegetable intake

Fibre: Different Types, Different Roles

Fibre is not digested into glucose but supports gut health, blood sugar regulation, satiety, and appetite control. Understanding the types of fibre helps make practical food choices.

1. Soluble Fibre

• Definition: Dissolves in water to form a gel-like substance
• Function/Effect: Slows digestion, helps regulate blood sugar, can lower cholesterol; often fermentable
• Examples: Chia, oats, legumes, apples, citrus, avocado, sweet potato, slippery elm

Health Insight: Fibre and Starch Co-exist
Fibre often occurs alongside starch in foods. While fibre slows digestion and helps regulate blood sugar, the starch portion can still be rapidly absorbed if the food is processed. Many foods also contain both soluble and insoluble fibre, which together influence digestion, glucose release, and satiety.

2. Insoluble Fibre

• Definition: Does not dissolve in water
• Function/Effect: Adds bulk to stool, supports bowel regularity; mostly non-fermentable
• Examples: Broccoli, cauliflower, cabbage, leafy greens, zucchini, avocado

3. Fermentable Fibre

• Definition: Broken down by gut bacteria to produce short-chain fatty acids
• Function/Effect: Supports microbiome diversity, protects the gut lining, reduces inflammation
• Examples: Resistant starch (cooled potatoes, green bananas, cooked and cooled rice), inulin (chicory root, Jerusalem artichoke, onions), oats, legumes

4. Non-Fermentable Fibre

• Definition: Passes largely intact through the colon
• Function/Effect: Adds bulk, improves satiety, promotes regular bowel movements
• Examples: Some vegetables (parsnips and beetroots), apple skins, flaxseeds, psyllium

Health Insight: Fibre Tolerance Is Individual
Some individuals with sensitive or inflamed guts may benefit from temporarily reducing raw, non-starchy vegetables. Insoluble or highly fermentable fibres in these foods can irritate an inflamed gut and worsen symptoms such as bloating, discomfort, or loose stools. Cooked, peeled, or lower-fermentable vegetables are often better tolerated while still providing nutrients and supporting gut healing.

Individual Carbohydrate Tolerance

Carbohydrate needs are not static. Adjustments may help those experiencing insulin resistance, fatigue, inflammation, digestive issues, or challenges with weight regulation.

Temporary Strategies

• Limit refined starches and sugars to reduce rapid glucose spikes
• Prioritise protein, healthy fats, and non-starchy vegetables for balanced meals
• Reduce highly fermentable or raw vegetables temporarily if gut symptoms occur; opt for cooked, peeled, or lower-fermentable options

Activity Matters

Physical activity improves carbohydrate tolerance. Strength training, endurance exercise, and daily movement increase the body’s ability to use glucose efficiently.

Listen to Your Body

Monitor your personal response to carbohydrates:

• Energy after meals
• Hunger timing
• Mental clarity
• Sleep quality
• Digestive comfort

Structuring Meals: The Rule of Thirds

A simple, practical approach to balanced meals:

• One third protein: Supports muscle maintenance, satiety, and hormone balance
• One third vegetables or whole-food carbohydrates: Non-starchy vegetables, with starches included based on tolerance and activity level
• One third healthy fats: Slows digestion and supports nutrient absorption

Health Insight: Flexible, Not Fixed
Portions shift naturally based on activity level, metabolic health, digestive capacity, and life stage.

Conclusion

Carbohydrates are not inherently harmful. Considering quality, preparation, pairing, activity level, and individual tolerance allows for strategic use without fear, overconsumption, or adverse effects. Applying simple pairing strategies, choosing intact, whole foods, and observing your body’s responses provides a practical framework for balanced and functional eating.

See you next week!

Sammy

Disclaimer

This article is intended for general education and informational purposes only. It does not constitute medical, nutritional, or personalised health advice and should not be used as a substitute for consultation with a qualified health professional. Individual needs vary based on health history, medical conditions, medications, and other personal factors. Always seek guidance from an appropriately trained practitioner before making significant changes to your diet or lifestyle, particularly if you have a medical condition or are experiencing ongoing symptoms.

References

1.   Jenkins DJA. Dietary Carbohydrates and Their Glycemic Responses. JAMA. https://jamanetwork.com/journals/jama/fullarticle/393059

2.   Carbohydrate quality, glycemic index, glycemic load and cardiometabolic risks: dose‑response meta‑analysis. https://pubmed.ncbi.nlm.nih.gov/32278608

3.   Importance of carbohydrate quality: meta‑analyses and cohort evidence. https://www.ovid.com/journals/tjon/abstract/10.1093/jn/nxac039~importance-of-carbohydrate-quality-what-does-it-mean-and-how

4.   Higher fiber, higher carbohydrate diets for diabetes management: meta‑analysis. https://pubmed.ncbi.nlm.nih.gov/39295498

5.   Effects of whole grains on glycemic control: systematic review & meta‑analysis. https://nutritionj.biomedcentral.com/articles/10.1186/s12937-024-00952-2

6.   Dietary Fiber, Carbohydrate Quality and Mortality Risk in Diabetes. https://pmc.ncbi.nlm.nih.gov/articles/PMC3426551

7.   Glycemic index & health outcomes research. https://www.sugarnutritionresource.org/news-articles/carbohydrate-quality

8.   Kresser C. Is the Glycemic Index Useful? https://chriskresser.com/is-the-glycemic-index-useful/

9.   Kresser C. Carbohydrate density & gut health concept. https://chriskresser.com/leptin-resistance-and-its-role-in-obesity/comment-page-1/