Intermittent fasting (IF) is a time-honored practice that’s supported by a growing body of research. From increasing weight loss to reducing triglycerides and inflammation in the body, fasting has unique benefits for an individual (*)(*). But what about the best intermittent fasting schedule? Is one approach better than the other?
If you’re interested in fasting times, this guide explains what each schedule entails so that you can decide which one to use!
Just keep in mind that different life situations can affect your fasting strategy, so it’s important to consider the “bigger picture” if you’re using IF to reach a goal rather than stressing over small details.
There is no single intermittent fasting schedule that will work for everyone. Certain schedules are better suited for complete beginners while some may appeal to those who like to keep their day simple. The only way to determine which schedule is optimal is to try it yourself.
Below are some factors you should consider when choosing from various intermittent fasting times:
- Health status and medication: While intermittent fasting can provide many benefits, some schedules might be contraindicated for people who need to take medication with food (to reduce stomach irritation) at certain times. Examples are fast-acting insulin for those with diabetes, non-steroidal anti-inflammatory drugs (NSAIDs), and corticosteroids.
- Daily schedule or routine: What does your typical day look like? For example, if your mornings are always busy and you’re not hungry for breakfast, it might be better for you to include mornings as part of your fasting window (the time you’re not eating).
- Social commitments: Meals with the family and social gatherings also need to be considered when planning an intermittent fast. These commitments may take precedence over a fasting schedule which you find attractive but impractical.
- Menstrual cycle: If you’re a woman, the week before your period can be particularly difficult due to premenstrual syndrome (PMS), which causes food cravings, mood swings, and low energy (*). In these situations, a shorter 12-hour fast would be more tolerable than a 14- or 16-hour fast.
- Health and fitness goals: Longer fasts seem to accelerate weight loss due to increased fat-burning and a reduction in the calories you consume. On the other hand, shorter fasts may be more advantageous for preventing muscle loss (for those whose goals include building muscle).
- Quality of your sleep: Not getting a good night’s sleep can negatively impact your mood — plus it makes you hungrier (*). This will limit your fast.
- Exercise routine: Strenuous exercise and longer fasting times do not go well together. Pick a schedule based on your workout intensity and duration, and perform your workout preferably during your feeding window or shortly before your fast begins.
- Your experience with fasting: Unless you’ve done intermittent fasting before, it’s best to start with the minimum fasting time, such as a 12-hour fast or simply skipping a meal. Remember that fasting is considered a stressor, so it’s good to gradually increase your number of hours until you feel comfortable.
Individuals who are new to IF can choose from different methods depending on what suits their circumstances and needs at the moment. We’ve outlined 7 options, each with an explanation of how they work and strategies to follow.
Skipping a meal
Also known as “spontaneous fasting,” skipping a meal means exactly what it says: you skip a meal — breakfast, lunch, or dinner — if you don’t feel like eating or are not hungry at all. Spontaneous fasts are simple because there are no specific rules involved. All you need to do is forgo food. You can always resume eating when you feel hungry!
As the most intuitive intermittent fasting for beginners, skipping a meal is an effective way to lower your daily calorie intake and lose weight naturally. It normalizes not having to eat three meals a day. However, you need to be aware of a potential drawback, which is the tendency to eat low-quality foods on your next meal (*).
If you’re thinking of trying this fasting schedule, listen to your hunger cues. Let hunger be your guide to eat something, especially if it’s affecting your productivity. Furthermore, avoid overcompensating by consuming big portion sizes and choosing high-carb and sugary foods during your eating window.
12-hour intermittent fasting
The other term for a 12-hour fast is “overnight fasting.” Choose a time in the evening to start your fast — let’s say, for instance, from 8 p.m. to 8 a.m. In that case, you would need to stop eating before 8 p.m. and resume eating after 8 in the morning. Given that this type of fast includes the time you spend sleeping, it’s practical for all beginners.
People who benefit from this approach include those who want to stop late-night eating. There’s a reason behind the age-old advice to avoid midnight snacking as much as possible. Harvard Medical School investigators did a study and found that eating later in the day caused participants to burn calories at a slower rate. Furthermore, adipogenesis (the formation of fat cells) increased (*).
To make your 12-hour fast successful, be sure to properly nourish yourself earlier in the day. Have breakfast and lunch with lots of healthy fats and protein to help you have greater satiety.
The 5:2 diet
The 5:2 intermittent fasting schedule involves fasting two days a week. On these two fasting days, you limit your intake to 500 calories (if you’re a female) or 600 calories (if you’re a male). Feel free to pick which days to fast depending on your schedule.
Since you’ll be having a small number of calories while fasting, make it worth your while by obtaining these 500-600 calories from filling foods. Eggs, non-starchy green vegetables, beef, chicken, and fish are some of the best examples.
14:10 intermittent fasting
To do this fast, eat within a 10-hour window and fast for the remaining 10 hours. For example, you can have breakfast at 7 a.m. and your last meal at 5 p.m.
Results of a randomized, controlled, virtual clinical trial showed that fasting for 14 hours each day for 8 weeks improved weight loss and fasting blood glucose in participants with obesity (*).
Like a 12-hour fast, a 14-hour fast is a good idea if you need help overcoming late-night eating habits and regulating your appetite, in addition to weight loss. Moreover, it aligns with your circadian rhythm since it includes your sleep time.
Alternate-day fasting or ADF means that you need to fast every other day. It’s simple: Just eat as usual one day, then fast the next day. For example, eat normally on Monday, Wednesday, and Friday, and fast on Tuesday and Thursday.
For those with experience fasting one to two days a week, ADF is a good approach to try. A randomized controlled trial finds that alternate-day fasting is equally effective whether you do it on a low-fat diet or high-fat diet (like the keto diet) (*).
If not eating anything during fasting days is too challenging for you — feel free to modify the ADF method by having a small meal or consuming around 500 calories. Here’s what 500 calories look like: a 100-gram salmon, two large eggs, and 80 grams of chicken breast.
16:8 intermittent fasting
Known as the “Leangains” fasting method, the 16:8 fast involves fasting for 16 hours and eating within an 8-hour window. While it can be practiced by beginners, some may experience potential side effects like fatigue, extreme hunger, and headaches — which result from not eating anything longer than usual.
Pick a time window when you prefer to have your meals. This can be from 7 a.m. to 3 p.m. (if you like having breakfast, lunch, and a light snack) or 12 p.m. to 8 p.m. (if you prefer skipping breakfast but having lunch and dinner).
An eight-week study done on 34 resistance-trained males found that consuming calories within an 8-hour period each day, along with resistance training, can lower fat mass, decrease blood glucose and insulin, and reduce inflammation (*).
If you want to try this IF schedule, we recommend starting with one day per week. Feeling hungry in the middle of your fast? Drink lots of water and zero-calorie electrolytes. You can also drink black coffee while fasting.
18:6 intermittent fasting
This is the opposite of the 16:8 fast. So, instead of fasting for 16 hours, you add two more hours to make it 18. Since it’s more advanced, it’s probably best to skip it until you get used to other fasting times mentioned on this list. Examples of eating windows are from 6 a.m. to 12 p.m. and 12 p.m. to 6 p.m.
Besides allowing yourself to adjust to less intense fasts, use the 18:6 fast to break through a weight loss plateau. On top of that, you may be able to enter autophagy (a vital process that removes damaged cells) which begins at around 17 or 18 hours of fasting.
This schedule is more challenging, which is why you need to support your body through proper hydration. Other beverages (aside from water) are fine as long as they don’t contain calories. Since 18 hours is a longer fast, break your fast properly by starting with a small meal that’s easy to digest. Bone broth is also an excellent choice!
Below are frequently asked questions on the best intermittent fasting schedule to help you learn more:
What’s the most effective intermittent fasting schedule?
The most effective schedule for fasting is the one you’re most comfortable with. To know this, you actually have to experience each fasting schedule, starting with the most flexible option, which is meal skipping or spontaneous fasting.
What’s the best intermittent fasting schedule for weight loss?
The best fasting approach for weight loss will also depend on how consistent you are with your chosen schedule, along with other lifestyle strategies you do outside intermittent fasting that support weight loss.
With that being said, an intermittent fasting schedule can be as effective as another schedule as long as you do it right. Besides sticking to a fast (unless you feel unwell), make sure you stay hydrated and eat the right foods during your feeding window.
What’s the best intermittent fasting schedule for women?
Pick a schedule that’s sustainable for you, such as the 14:10 intermittent fast or 16:8 intermittent fast. Longer fasts aren’t necessarily better, especially for aging women whose muscle mass declines due to hormonal changes that come with increasing age (*). Keeping your fasts short allows you to get enough protein and other nutrients for muscle maintenance.
There is no single best intermittent fasting method for beginners, and just about anyone can benefit from a fasting schedule as long as they get the basics right.
Before trying any of the schedules above, think about factors that will affect your ability to follow and maintain a fast, such as your current health status (and medications you’re taking), daily routine, and social commitments. Don’t forget to seek advice from a health professional if you need extra support.
Also, make sure to eat enough food in between fasts and prioritize whole foods.
CHAIR, Sek Ying; CAI, Hua; CAO, Xi∗; QIN, Yuelan; CHENG, Ho Yu; NG, Michael Timothy. Intermittent Fasting in Weight Loss and Cardiometabolic Risk Reduction: A Randomized Controlled Trial. Journal of Nursing Research 30(1):p e185, February 2022. | DOI: 10.1097/jnr.0000000000000469
Mount Sinai Health System. Mount Sinai researchers discover that fasting reduces inflammation and improves chronic inflammatory diseases. Mount Sinai Health System. https://www.mountsinai.org/about/newsroom/2019/mount-sinai-researchers-discover-that-fasting-reduces-inflammation-and-improves-chronic-inflammatory-diseases. Published August 22, 2019.
John Axelsson and others, Sleepiness as motivation: a potential mechanism for how sleep deprivation affects behavior, Sleep, Volume 43, Issue 6, June 2020, zsz291, https://doi.org/10.1093/sleep/zsz291
Zeballos E, Todd JE. The effects of skipping a meal on daily energy intake and diet quality. Public Health Nutr. 2020 Dec;23(18):3346-3355. doi: 10.1017/S1368980020000683. Epub 2020 May 13. PMID: 32398192; PMCID: PMC10200470.
Sampson K. Study looks at why late-night eating increases obesity risk. Harvard Gazette. https://news.harvard.edu/gazette/story/2022/10/study-looks-at-why-late-night-eating-increases-obesity-risk/. Published October 4, 2022.
Peeke PM, Greenway FL, Billes SK, Zhang D, Fujioka K. Effect of time restricted eating on body weight and fasting glucose in participants with obesity: results of a randomized, controlled, virtual clinical trial. Nutrition & Diabetes. 2021;11(1). doi:10.1038/s41387-021-00149-0
Klempel MC, Kroeger CM, Varady KA. Alternate day fasting (ADF) with a high-fat diet produces similar weight loss and cardio-protection as ADF with a low-fat diet. Metabolism. 2013 Jan;62(1):137-43. doi: 10.1016/j.metabol.2012.07.002. Epub 2012 Aug 11. PMID: 22889512.
Moro T, Tinsley G, Bianco A, Marcolin G, Pacelli QF, Battaglia G, Palma A, Gentil P, Neri M, Paoli A. 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 Oct 13;14(1):290. doi: 10.1186/s12967-016-1044-0. PMID: 27737674; PMCID: PMC5064803.