Quick answer: To do 16/8 intermittent fasting, choose an 8-hour eating window that fits your schedule, such as 11 AM to 7 PM, and fast for the other 16 hours. Plan two to three nutrient-dense meals, stay hydrated with water, tea and electrolytes, and break your fast with protein and healthy fats. Adjust as needed and aim for consistency.
Key takeaways
The 16/8 approach starts with choosing an eating window that fits your day, often fasting overnight into the morning.
Two or three nutrient-dense meals with protein, healthy fats, fruit and vegetables fill the window, and water is the main drink during the fast.
Breaking a fast gently with protein and healthy fats, and shortening the fast if you feel unwell, helps your body adapt.
Step 1: Choose your eating window
Many people fast overnight into the morning. Write down a timeframe and adjust until it fits.
Example windows
- 6 AM–2 PM (early risers)
- 8 AM–4 PM
- 11 AM–7 PM (popular)
- 12 PM–8 PM
- An earlier window may suit morning people; a later one may suit social schedules
Step 2: Plan your meals
Plan two to three nutrient-dense meals with protein, healthy fats, fruits and vegetables. See the intermittent fasting food cheat sheet.
Step 3: Stay hydrated
Make water as your main drink, and try water infused with lemon, cucumber or mint, or unsweetened tea. Bone broth is an option, though slightly controversial since it contains a few calories, and electrolyte water can help if you feel lightheaded.
Step 4: Adjust and stay consistent
If you feel unwell, shorten the fast. Consistency helps your body adapt.
Sample day (11 AM–7 PM)
- 11:00 AM: lunch, such as salad with grilled chicken, avocado and olive oil
- 2:00 PM: snack, such as Greek yogurt with berries and nuts
- 6:00 PM: dinner, such as salmon with roasted vegetables
- 7:00 PM: eating window closes
- 10:30 PM: bed (finish eating at least two hours before)
How to break a fast
Start with protein and healthy fats, such as eggs, nuts or lean meat with vegetables. Eat slowly and listen to your body.
Healthy aging lens
Finishing meals earlier in the evening may support blood sugar. See insulin sensitivity and check who should not fast first.
What the research shows
The 16/8 method has been tested in several randomized trials.
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.
16/8 with strength training (Moro 2016, randomized trial). 34 resistance-trained men ate the same calories either within an 8-hour window or across the day while lifting for 8 weeks. The 16/8 group lost more fat mass while keeping their muscle and strength; testosterone and IGF-1 dipped slightly in that group. A limitation is that this was a small group of young, trained men, so the findings may not apply to women, older adults or beginners.
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.
Strength of the evidence: Overall, 16/8 eating is generally well tolerated, but on its own it has not clearly beaten regular meal patterns for weight loss.
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 window would suit my schedule, sleep and blood sugar best?
How should I set up a 16/8 window around my work and sleep schedule?
What can I eat or drink during my fasting hours?
Which signs would tell me 16/8 is not right for me?
Frequently asked questions
Can I drink coffee during a 16/8 fast?
Black coffee and plain tea are generally fine.
What should I eat to break my fast?
Protein and healthy fats with vegetables.
Is a later or earlier window better?
Choose what you can sustain; earlier windows may suit blood sugar.
Do I need to fast every day?
Consistency helps, but flexibility is fine.
Sources
- Gabel K, et al. Effects of 8-hour time restricted feeding on body weight and metabolic disease risk factors in obese adults: A pilot study. Nutr Healthy Aging 2018. PMID: 29951594. https://pmc.ncbi.nlm.nih.gov/articles/PMC6004924/
- Popkin BM, D’Anci KE, Rosenberg IH. Water, hydration, and health. Nutr Rev 2010. PMID: 20646222. https://pmc.ncbi.nlm.nih.gov/articles/PMC2908954/
- Gu C, et al. Metabolic Effects of Late Dinner in Healthy Volunteers-A Randomized Crossover Clinical Trial. J Clin Endocrinol Metab 2020. PMID: 32525525. https://pmc.ncbi.nlm.nih.gov/articles/PMC7337187/
- Jamshed H, et al. Early Time-Restricted Feeding Improves 24-Hour Glucose Levels and Affects Markers of the Circadian Clock, Aging, and Autophagy in Humans. Nutrients 2019. PMID: 31151228. https://pmc.ncbi.nlm.nih.gov/articles/PMC6627766/
- National Institute on Aging: Research on intermittent fasting shows health benefits
- MedlinePlus: Dehydration
- 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/
- Moro T, et al. Effects of eight weeks of time-restricted feeding (16/8) on basal metabolism, maximal strength, body composition, inflammation, and cardiovascular risk factors in resistance-trained males. J Transl Med 2016. PMID: 27737674. https://pubmed.ncbi.nlm.nih.gov/27737674/
- 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/
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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