Quick answer: Intermittent fasting doesn’t dictate what you eat, but food quality shapes results. Paleo and keto are popular pairings. Whatever your style, build meals around quality protein, complex carbohydrates, healthy fats (especially omega-3s), fiber-rich whole foods and colorful, antioxidant-rich produce, and limit ultra-processed foods and added sugar.
Key takeaways
Intermittent fasting can be paired with other eating styles, such as paleo or keto.
Each meal can include protein, complex carbohydrates such as vegetables and fruit, and mostly unsaturated fats from olive oil, avocado and nuts.
High-fiber and brightly colored foods keep you full, feed gut bacteria and supply antioxidants.
Pairing fasting with a diet
The paleo diet emphasizes whole, unprocessed foods; keto is high-fat and low-carb. Learn more: the ketogenic diet and carbohydrates on paleo.
Protein
Protein builds and repairs muscle, skin and hormones. Include meat, fish, eggs, dairy if tolerated, legumes or tofu in each meal.
Carbohydrates
Choose complex carbs such as vegetables, fruit, whole grains and legumes for steady energy, rather than refined sugars.
Fats
Saturated fats include butter, fatty meats and coconut oil, so use them in moderation. Monounsaturated fats come from olive oil, avocado and nuts, and polyunsaturated fats from fatty fish, walnuts, flax, chia and hemp seeds (omega-3s). Grass-fed meat and pasture-raised eggs have a better omega-3 profile.
Whole, high-fiber foods
Fiber keeps you full and feeds gut bacteria. Include vegetables and fruit with the skin, legumes, oats and seeds.
Antioxidant-rich foods
Brightly colored fruits and vegetables help protect cells from oxidative damage.
Quick reference
For a printable list, see the intermittent fasting cheat sheet.
Healthy aging lens
Protein, fiber, omega-3s and antioxidants each support processes that matter for aging: muscle, the microbiome, inflammation and cellular protection.
What the research shows
Studies of fasting schedules show that what and how much you eat in the eating window still matters.
Time-restricted eating plus calorie restriction (Liu 2022, randomized trial). 139 adults with obesity in China followed the same calorie target (1,200 to 1,800 kcal a day) for 12 months, either eating only between 8 a.m. and 4 p.m. or eating at any time. Both groups lost weight (8.0 kg vs. 6.3 kg), but the 1.8 kg difference was not statistically significant, and waist size, body fat, blood pressure and lab markers were also similar. A limitation is that the study cannot separate the effect of meal timing from the effect of calories, because both groups cut calories.
16:8 eating without other changes (Lowe 2020, randomized trial). 116 adults with overweight or obesity either ate only between noon and 8 p.m. or ate three regular meals a day for 12 weeks. The 16:8 group lost an average of 0.94 kg and the regular-meal group 0.68 kg, and the difference between groups (0.26 kg) was not significant. In the in-person subgroup, the 16:8 group lost slightly more lean mass. The main limitation is the short 12-week length, and food intake was self-reported through an app.
Ultra-processed vs. unprocessed food (Hall 2019, inpatient randomized crossover trial). 20 adults lived at the NIH Clinical Center and ate an ultra-processed diet for 2 weeks and an unprocessed diet for 2 weeks, with meals matched for calories, sugar, fat, fiber and sodium and eaten as freely as they liked. On the ultra-processed diet they ate about 508 kcal more per day and gained 0.9 kg; on the unprocessed diet they lost 0.9 kg. A limitation is that it was a small, short study in a controlled setting, not real life.
Strength of the evidence: These trials suggest food quality and total calories drive results more than the clock alone.
When to see a naturopathic doctor
It may be time to see a naturopathic doctor if you have diabetes, take blood sugar or blood pressure medication, or have a chronic condition, or if you are pregnant, breastfeeding, underweight, or have a history of disordered eating. The same is true if fasting leaves you dizzy, shaky or exhausted, or if you want a fasting approach tailored to your health goals.
See a medical provider promptly for fainting, confusion, chest pain, a racing heartbeat, or very low blood sugar symptoms such as shaking, sweating and confusion.
Want a fasting plan that fits 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 eating style would pair best with fasting for my health goals?
Which food groups should my meals be built around while fasting?
How can I balance my plate when I only eat two meals a day?
Are there food groups I should limit for my own needs?
Frequently asked questions
What should I eat during my eating window?
Protein, vegetables, fruit, healthy fats and fiber-rich whole foods.
Can I combine fasting with keto?
Yes, many people do; it isn’t required.
Are carbs okay when fasting?
Yes, focus on complex carbs.
Which fats are best?
Olive oil, avocado, nuts and omega-3-rich fish.
Sources
- Wang X, et al. Fruit and vegetable consumption and mortality from all causes, cardiovascular disease, and cancer: systematic review and dose-response meta-analysis of prospective cohort studies. BMJ 2014. PMID: 25073782. https://pmc.ncbi.nlm.nih.gov/articles/PMC4115152/
- Hall KD, et al. Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake. Cell Metab 2019. PMID: 31105044. https://pmc.ncbi.nlm.nih.gov/articles/PMC7946062/
- Bauer J, et al. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. J Am Med Dir Assoc 2013. PMID: 23867520. https://pubmed.ncbi.nlm.nih.gov/23867520/
- 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/
- 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/
- NIH Office of Dietary Supplements: Omega-3 Fatty Acids
- MedlinePlus: Dietary Fiber
- Liu D, et al. Calorie Restriction with or without Time-Restricted Eating in Weight Loss. N Engl J Med 2022. PMID: 35443107. https://pubmed.ncbi.nlm.nih.gov/35443107/
- Lowe DA, et al. Effects of Time-Restricted Eating on Weight Loss and Other Metabolic Parameters in Women and Men With Overweight and Obesity: The TREAT Randomized Clinical Trial. JAMA Intern Med 2020. PMID: 32986097. https://pubmed.ncbi.nlm.nih.gov/32986097/
- Hall KD, et al. Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake. Cell Metab 2019. PMID: 31105044. https://pubmed.ncbi.nlm.nih.gov/31105044/
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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