Whether you’re new to keto or have been doing it for a while, you may be wondering how to do intermittent fasting. At one point, the health and wellness industry advised eating 5-6 small meals per day for optimal metabolism. The claim was that smaller meals lead to weight loss, while a fasted state puts the body into “starvation mode,” causing it to hold on to calories.
However, more recent research reveals the exact opposite — that there are several benefits of intermittent fasting, which is the practice of going extended periods without food. A fasting diet may boost metabolism, improve insulin sensitivity, and help transition your body into a fat-burning state.
Intermittent fasting works similar to a ketogenic diet, depriving your body of glucose to transition to a fat-burning state. Fasting has many health benefits, including weight loss, fat loss, and balanced blood sugar and insulin levels. It might also prevent Alzheimer’s and chronic diseases, reverse insulin resistance, and lead to a longer lifespan[*].
Many proponents of fasting say that mentally, fasting is easier to handle than calorie restriction or calorie counting. Intermittent fasting is extremely popular among those following low-carb diets like keto because it helps generate ketones and induce a state of ketosis[*], which can help you burn fat.
There are multiple approaches to fasting. You’ll learn how to do intermittent fasting several different ways, and how it can benefit you based on your goals, lifestyle, and activity level.
Types of Intermittent Fasting
Intermittent fasting is a cycle between eating within a certain window of time, then abstaining from food for a defined period. The length and frequency of your fasting window depend on the approach you take.
Daily Window Fasting
A daily window fasting protocol involves eating within a certain time period, usually lasting 8-10 hours, every day of the week. One such method, commonly called 16/8 fasting — or the lean gains protocol — involves eating all meals within an 8-hour period, then not eating the remaining 16 hours of the day.
For example, you could eat breakfast, your first meal, at 10 a.m., dinner, your last meal, at 6 p.m., and then fast until breakfast the next day.
If you’re new to fasting, you might consider lengthening your eating window. Start with 10 hours (for example, eating breakfast at 9 a.m. and dinner at 7 p.m.) and progress from there. If you’re experienced with fasting, you might conduct 20-hour fasts, eating within a 4-hour time frame.
With daily window fasting, consistency matters more than the length of your eating window. Veteran fasters might eat one large meal per day (23:1), while a person just starting out may eat within a 10-hour window. The key is to repeat the same cycle of fasting and eating periods each day of the week.
Daily Intermittent Fasting Plan
Try these various schedules, selecting the eating plan that works best for your lifestyle and fasting experience. Remember to repeat the same cycle every day.
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- 14:10: Eat between 9 a.m.-7 p.m.; fast between 7 p.m.-9 a.m. the following day.
- 16:8: Eat between 10 a.m.-6 p.m.; fast between 6 p.m.-9 a.m. the following day.
- 20:4: Eat between noon-4 p.m., fast between 4 a.m.-noon the following day.
- 23:1: Eat one big meal per day, at whatever hour you wish.
If you’re new to intermittent fasting and the practice intimidates you, skipping meals is a good gateway. If you eat a large dinner, try skipping breakfast. If you’re busy midday, skip lunch and eat an early dinner.
While conventional wisdom once warned to never skip meals and labeled breakfast as the “most important meal of the day,” new research is questioning these beliefs. Skipping meals can boost your metabolism, not hinder it. It seems that skipping breakfast could be just as beneficial as skipping dinner, so take your pick[*].
When you skip one meal, be careful not to overeat at the next. The goal of skipping meals is to become an intuitive eater — eating only when you’re hungry, not because it’s “that time” to enjoy a meal. It’s not an excuse to binge at your next sit-down meal or practice other forms of disordered eating.
Skipping Meals Schedule
If you choose to skip meals rather than adhere to a regular fasting schedule, your eating schedule might look different each day of the week. Start by skipping one meal when you’re not hungry, then aim to skip several meals scattered throughout the week.
- Skip breakfast: Eat only lunch and dinner.
- Skip lunch: Eat breakfast, fast throughout the workday, then eat dinner.
- Skip dinner: Enjoy breakfast and lunch, then do an overnight fast.
Fasting on Alternate Days
Alternate-day fasting consists of fasting one day, then eating regularly the next. On this schedule, your caloric intake on fasting days will be roughly 25% of your usual calories. For example, if you typically eat a 2,000-calorie diet, you’ll limit your calorie intake to 500 calories during your fasting time.
In a study done by the National Institute of Health, there were many success stories associated with alternate-day fasts. Alternate-day fasting was more effective than calorie restriction or following a consistent low-calorie diet. It was also shown to increase life span, maintain muscle mass, and decrease inflammation [*].
Alternate-Day Fasting Schedule
To stick to an alternate-day fasting schedule, follow the cycle outlined below. You can start any day of the week as long as the cycle remains the same. While only four days are listed, keep the cycle going throughout the entire week.
- Day 1: Eat 25% of usual calories (roughly 500 calories throughout the day).
- Day 2: Eat 1,600-2,000 calories.
- Day 3: Eat 25% of usual calories (roughly 500 calories throughout the day).
- Day 4: Eat 1,600-2,000 calories.
For a 24-hour fast (also called eat-stop-eat), you’ll select one day per week and not eat on that particular day week to week.
For example, you could eat breakfast at 7 a.m. on Mondays, then not eat until 7 a.m. on Tuesdays.
If this seems too extreme to you, you could aim to eat in the middle of the day, around 2 p.m., so it doesn’t feel as though you’re going an entire day without food.
The 24-hour fasting approach may be especially helpful with losing body fat. Most people only do one 24-hour fast day per week. Those who are experienced with fasting may choose up to two separate days per week to conduct a 24-hour fast.
However, there are conflicting claims as to whether going 48 hours without food in a single week is helpful or harmful[*].
24-Hour Fasting Schedule
To complete a 24-hour fast, choose the day that you are least physically active. Perhaps choose a rest day from the gym or a day where you will do light yoga rather than rigorous exercise. A fast schedule might look like this:
- Sunday: Eat 1,600-2,000 calories and conduct regular physical activity.
- Monday: Eat lunch at noon, fast the remainder of the day. Take a rest day from the gym.
- Tuesday: Fast through breakfast, eat lunch, and conclude your fast. Resume physical activity and eat dinner as usual.
Frequency of Intermittent Fasting
Now that you understand how to do intermittent fasting, it raises a question: How often should you fast?
The answer varies from person to person. Most people implement the above schedules every week or every other week. If you’re new to fasting, start with a moderate schedule, trying it every other week or every three weeks. If your body adapts well, aim for a regular weekly schedule.
There’s no wrong answer here. Pay close attention to how your body responds to your fasting schedule and adjust it as needed. Keep in mind that life changes can happen. You may need to tweak your schedule to allow for social gatherings, vacations, and physical activity or competition.
Calories and Nutrition
When implementing an intermittent fasting schedule, make sure you get enough calories during your eating windows. Be mindful of what you’re eating in between fasting periods, focusing on real, whole foods, so you get the most nutrients per calorie.
Fasting is no excuse to skimp on optimal nutrition. In fact, since you’re eating less, you should get the most nutrients you possibly can from those meals. Don’t allow fasting to be the reason to eat donuts, soda, and candy. It’s also essential to drink plenty of water.
The Bottom Line on How to Do Intermittent Fasting
There’s no single solution on how to do intermittent fasting for everyone, but just about any healthy person can benefit from the practice.
Those who are intimidated by stricter fasting methods might try skipping meals first, then moving into a 16:8 fast. If you find these beneficial, move on to an alternate-day fast where you’ll consume 500 calories on fasting days. Finally, try a full 24-hour fast one day per week.
Intermittent fasting is generally safe to do as often as you’d like. Just make sure you’re eating enough food in between and eating whole foods. And lastly, don’t be afraid to experiment to find what works best for you.
16 thoughts on “How to Do Intermittent Fasting: 4 Fasting Schedules to Try”
Ive been fasting 16/8 for 5 days now and havnt had a bowel movement in this time. I have not changed my diet..just the times. I break-fast at 12-1pm. I have a very slow bowel transit and constantly battle with constipation. I did have this under control by eating oats with added bran,prunes and rhubarb every morning, drinking only water all day (between 2-3 litres) and watching what I eat the rest of the day ie healthy tasty food with vegetables and pulses seem to work for me. Stick to that religiously and I’ll go everyday. Stray and I won’t. I’m 53 5’5 and 10st 13lb. I want to lose 1st. I have osteoarthritis and lots of pain on exercise so take it easy but am relativly active. Can anyone offer any advice please. I don’t want to give this up. I don’t ‘diet and IF seems to suit me
Bone broth helped me tremendously! I go every day now as opposed to once or twice a week!
Have you tried taking magnesium daily?? I always go about an hour after I open my window to eat. This IF has healed my constipation problems.
I have the same problem. Now I take magnesium like Natural Calm and now they have Natural Calm Gut Health. So it’s got some probiotics. That and I’ll add just a dash/sprinkle of miralax. I take this right before I go to bed and let it work all night.
There are some really good recipes out there that include psyllium husk in them. Really good. That will help you. Also make sure you eat some green veggies. Too much protein will be hard on the digestive system. Suggest you pick up the beginners keto diet cookbook by Martina Slajerova. The jalapeño cheese muffins are the best.
Awesome Post!! I am happy that I came across with your site this article is on point,thanks for sharing and have a fantastic day.
I been fasting for a month every day every 24hr is that bad or good
You need to eat more fat and very low carbs
I blend 2 cups collard greens , chai seeds, applesauce unsweetened, prunes , plain fage yogurt, almond milk. I used to have the worst constipation all of my life and this blend wit two teaspoons of garden of life magnesium powder and I have not had an issue since!! Try it for my people that have had terrible digestive issues with constipation . I do intermittent fasting where my window to eat is is 2 to 1030 pm everyday with Whole Foods . Hope this helps someone
I have a green drink with psyllium, chia, spinach,fresh ginger, kale and a lemon squeeze.
I may add a protein mix(vanilla or choc.) with mint leaves. Never have an issue. Drink LOTS and Lots of water..
Great advice. Thank You for the tips! I am going to try this!
Just wondering when doing the 16 8 methid should I do it in a row or like every other day.
The key fasting is to repeat it each day of the week. If you’re new to fasting you might want to start with 10 hours and slowly progress from it.
With daily fasting, consistency matters but you can also have an alternate day fasting. You can try each schedule of fasting and then stick what works for you.
Try drinking pink salt water on empty stomach..add 1 tbsp in 1 liter water..it helped me a lot..
Try drinking pink salt water..add 1 tbsp of pink salt in 1 liter of water..it helped me a lot.
My wife has the same problem. What we did to fix it is blend about 1 cup cooked spinach, 500 grams berries, 1 cup flax seed, 1/2 cup blackstrap molasses (MUST be blackstrap) and enough coconut water to fill the blender to the top. Blend fully then divide into 7 small containers and freeze. Thaw one over night and drink in that morning. My wife used to go every 3 days, now she goes daily or sometimes 2 times a day. Part of the reason is that blackstrap molasses is a natural laxative and so is all that fiber. Blackstrap also gives you a pretty decent dose of very bioavailable iron.