DIETS
Intermittent fasting
A diet of when, not what: a daily eating window that fits with any other diet
- Eat
- Anything, within your eating window
- Popular plans
- 13:11, 14:10, 16:8, 18:6, 5:2
- During the fast
- Water, black coffee, plain tea
- Combine with
- Any of the diets on this site
What it is
Intermittent fasting means going without food for set periods. The most common form is time-restricted eating: fasting overnight and into the morning, then eating within a window of 6 to 10 hours. Other forms are the 5:2 diet (two low-calorie days a week) and alternate-day fasting. Because it doesn’t say what to eat, it pairs easily with the Mediterranean, low-carb or any other diet. Fasting Tracker’s website explains every plan.
The main plans
| Plan | How it works | Good for |
|---|---|---|
| 13:11 or 14:10 | Fast overnight, eat in a 10 to 11-hour window | Beginners |
| 16:8 | Fast 16 hours, eat in 8, often noon to 8 pm | The most popular plan |
| 18:6 | Fast 18 hours, eat in 6 | Experienced fasters |
| 5:2 | Eat normally 5 days, about 500 to 600 kcal on 2 | People who prefer weekly rules |
| Alternate-day | Eat little or nothing every other day | Few people: hard to keep up |
A sample day
16:8, one day
- Until noonWater, black coffee or plain tea
- 12:00Lunch: lentil soup, salad and whole-grain bread
- 16:00Snack: Greek yogurt and fruit
- 19:30Dinner: fish, potatoes and vegetables; the window closes at 20:00
What the research found
Key study
The same loss as cutting calories
- Randomized trial
- 139 adults with obesity
- 12 months
All participants ate fewer calories; half also ate only between 8 am and 4 pm. After a year, the eating-window group had lost 8.0 kg and the other group 6.3 kg, a difference that wasn’t statistically significant.
Key study
A window alone isn’t magic
- Randomized trial
- 116 adults with overweight
- 12 weeks
Participants ate only between noon and 8 pm, with no other advice, or ate three meals a day. Weight loss was small and similar in both groups, so the window needs to lead to eating less to make a difference.
In a year-long trial, alternate-day fasting and daily calorie cutting led to similar weight loss, but more people dropped out of alternate-day fasting 3. An umbrella review of the trials found that intermittent fasting leads to modest weight loss and improvements in several metabolic markers compared with eating as usual 4. Its main advantage is practical: a clear rule about when to eat.
Good for
- People who don’t want to count
- Busy days with fewer meals to plan
- Combining with any other diet
Watch out for
- Hunger in the first week or two
- Social meals outside your window
- Not suitable when pregnant, under 18 or with a history of eating disorders
How to start
Five first steps
- Start with a 12 or 13-hour overnight fast: stop eating after dinner, eat breakfast a little later.
- Stretch it to 14 hours when that feels easy, then to 16 if you like.
- Drink water, black coffee or plain tea while fasting.
- Break your fast with a meal that has protein and vegetables.
- Keep eating well in your window: the window doesn’t cancel out the food.
Start with Fasting Tracker
Questions
Is intermittent fasting better than calorie counting?
For weight loss, they lead to similar results in trials 1,3. Choose the one you find easier to keep up.
What can I drink while fasting?
Water, black coffee and plain tea. Anything with calories, milk or sugar ends the fast.
Which plan should I start with?
13:11 or 14:10, which mostly means not eating after dinner. Move to 16:8 when that feels easy.
Sources
- Liu D, Huang Y, Huang C, et al. Calorie Restriction with or without Time-Restricted Eating in Weight Loss. N Engl J Med. 2022;386(16):1495-1504. doi.org/10.1056/NEJMoa2114833
- Lowe DA, Wu N, Rohdin-Bibby L, 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;180(11):1491-1499. doi.org/10.1001/jamainternmed.2020.4153
- Trepanowski JF, Kroeger CM, Barnosky A, et al. Effect of Alternate-Day Fasting on Weight Loss, Weight Maintenance, and Cardioprotection Among Metabolically Healthy Obese Adults: A Randomized Clinical Trial. JAMA Intern Med. 2017;177(7):930-938. doi.org/10.1001/jamainternmed.2017.0936
- Patikorn C, Roubal K, Veettil SK, et al. Intermittent Fasting and Obesity-Related Health Outcomes: An Umbrella Review of Meta-analyses of Randomized Clinical Trials. JAMA Netw Open. 2021;4(12):e2139558. doi.org/10.1001/jamanetworkopen.2021.39558
MAKE IT A HABIT
Any diet.
Your eating window.
Fasting Tracker is a free intermittent fasting app for iPhone, iPad and Apple Watch.
Download Fasting Tracker
dieting.app is general information, not medical advice. If you are pregnant or breastfeeding, have diabetes, kidney disease or a history of eating disorders, or take medication, talk to your doctor before changing how you eat.