Quick answer: On keto, spend your limited carbs on fiber-rich, nutrient-dense foods: leafy greens, non-starchy vegetables, small amounts of berries, nuts and seeds, fermented vegetables and coconut. Avoid added sugars, syrups, juices, sweets, refined grains and higher-sugar fruits like bananas and grapes.
Key takeaways
On keto, carbohydrates come mainly from leafy greens, low-carb vegetables, berries, nuts and seeds.
Sugar in all its forms, juice, refined-flour foods, grains and starchy vegetables are the carbohydrates to avoid.
Fiber-rich vegetables are digested slowly and feed gut bacteria that make short-chain fatty acids.
Carbs to include
- Leafy greens: spinach, kale, lettuce, arugula, chard
- Low-carb vegetables: broccoli, cauliflower, zucchini, peppers, asparagus
- Berries: raspberries, blackberries and strawberries in small portions
- Nuts and seeds: almonds, walnuts, chia and flax
- Fermented vegetables: sauerkraut and kimchi
- Coconut: unsweetened coconut and coconut and almond flours for baking
- Avocado
Carbs to avoid
- Sugar in all forms, high fructose corn syrup, honey, maple syrup and agave
- Soft drinks and fruit juice
- Candy, pastries and refined-flour baked goods
- Sugary breakfast cereals
- Jams and jellies with added sugar
- Higher-sugar fruits such as bananas, grapes and pineapple
- Grains, potatoes and most legumes
Simple vs. complex carbs
Simple sugars spike blood sugar quickly. Complex, fiber-rich carbs from vegetables are digested slowly. See understanding macronutrients and net carbs.
Healthy aging lens
Fiber feeds beneficial gut bacteria, which make short-chain fatty acids that support the gut lining and metabolic health.
What the research shows
Low-carbohydrate trials show how carbohydrate type and amount affect results.
Fiber and carbohydrate quality (Reynolds 2019, series of meta-analyses). Commissioned in part by the World Health Organization, this work combined 185 cohort studies and 58 clinical trials with 4,635 trial participants. People with the highest fiber intakes had 15% to 30% lower rates of heart disease, stroke, type 2 diabetes and colorectal cancer than those with the lowest, and the greatest benefit was seen at 25 to 29 g of fiber a day. A limitation is that most of this evidence is observational, and it applies to the general population rather than people with existing chronic disease.
Healthy low-carb vs. healthy low-fat (Gardner 2018, DIETFITS randomized trial). 609 adults without diabetes were coached for 12 months on either a healthy low-fat or a healthy low-carbohydrate diet, with both groups told to focus on whole, minimally processed foods. Weight loss was nearly the same (5.3 kg vs. 6.0 kg), and neither genetic testing nor insulin response predicted who did better on which diet. A limitation is that the low-carb group averaged 30% of calories from carbohydrate, so this was not a strict ketogenic diet.
Keto and appetite (Gibson 2015, systematic review and meta-analysis). This review pooled studies that rated hunger before and during ketosis in people following very-low-energy or ketogenic low-carbohydrate diets. People in ketosis reported being slightly less hungry and having less desire to eat. The authors note that the changes were small; the main benefit was that hunger did not rise as it usually does during weight loss. A limitation is that appetite was self-rated on scales, and the included studies were small and varied.
Strength of the evidence: Fiber-rich, low-starch vegetables fit best within keto limits; high fiber intake has broad support, while strict carbohydrate limits have more mixed long-term evidence.
When to see a naturopathic doctor
It may be time to see a naturopathic doctor if you have diabetes or take insulin, sulfonylureas or SGLT2 inhibitors (risk of low blood sugar or ketoacidosis), or if you take blood pressure medication or diuretics. The same is true if you have kidney, liver, gallbladder or pancreas disease, or high cholesterol, if you are pregnant, breastfeeding, or have a history of disordered eating, or if you want a keto plan tailored to your labs and goals.
See a medical provider promptly for nausea and vomiting, abdominal pain, confusion, fruity-smelling breath with rapid breathing, or very high blood sugar or ketone readings, which can signal ketoacidosis.
Want a keto plan that’s safe for your health?
A free 15-minute consultation with Dr. Kneessi. No cost, no obligation. In-office in Odenton, MD or by telehealth.
Questions to bring to your clinician
These questions can help you get the most out of your next visit.
Which carbohydrate foods should I keep for gut health and fiber while on keto?
Which low-carb vegetables and fruits could I add to my meals?
How can I get enough fiber on keto?
Are there carb foods I should still avoid, given my goals?
Frequently asked questions
What carbs can I eat on keto?
Leafy greens, non-starchy vegetables, berries, nuts and seeds.
Can I eat fruit on keto?
Small portions of berries fit best.
Are fermented vegetables keto?
Yes, unsweetened sauerkraut and kimchi are low in carbs.
Which carbs should I avoid?
Added sugars, juices, grains, starchy vegetables and higher-sugar fruits.
Sources
- Slavin JL, Lloyd B. Health benefits of fruits and vegetables. Adv Nutr 2012. PMID: 22797986. https://pmc.ncbi.nlm.nih.gov/articles/PMC3649719/
- Malik VS, et al. Sugar-sweetened beverages and risk of metabolic syndrome and type 2 diabetes: a meta-analysis. Diabetes Care 2010. PMID: 20693348. https://pmc.ncbi.nlm.nih.gov/articles/PMC2963518/
- Koh A, et al. From Dietary Fiber to Host Physiology: Short-Chain Fatty Acids as Key Bacterial Metabolites. Cell 2016. PMID: 27259147. https://pubmed.ncbi.nlm.nih.gov/27259147/
- Reynolds A, et al. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. Lancet 2019. PMID: 30638909. https://pubmed.ncbi.nlm.nih.gov/30638909/
- MedlinePlus: Carbohydrates
- MedlinePlus: Dietary Fiber
- Gardner CD, et al. Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion: The DIETFITS Randomized Clinical Trial. JAMA 2018. PMID: 29466592. https://pubmed.ncbi.nlm.nih.gov/29466592/
- Gibson AA, et al. Do ketogenic diets really suppress appetite? A systematic review and meta-analysis. Obes Rev 2015. PMID: 25402637. https://pubmed.ncbi.nlm.nih.gov/25402637/
This article is for educational purposes only and is not medical advice. It does not replace an individual evaluation. Talk with your healthcare provider before starting supplements or changing medications, especially if you are pregnant, nursing, or managing a health condition.
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