Alternate Day Fasting Diet (2023)

By Dietitian Juliette Kellow BSc RD



When it comes to losing weight, the idea of dieting only every other day may seem like an attractive one. After all, knowing we can indulge in our favourites ‘tomorrow’ may make dieting seem more bearable.

But as is always the case with anything that sounds too good to be true, there’s a downside – and in this case, it’s eating very little on the days in between.

One of the most popular diet books based on the idea of intermittent feasting and fasting is The Alternate-Day Diet, written by plastic surgeon Dr James Johnson. Here’s the lowdown…

What is The Alternate-Day Diet?

In a nutshell, this diet involves alternate day fasting, eating very little on one day followed by eating what you’d normally have the next day.

Isn’t that just another way to reduce calories overall?

It certainly is. But some experts believe that eating like this will make you healthier and help you live longer – as well as shifting those pounds.

What’s the theory of intermittent fasting?

The idea that restricting our calories makes us healthier and increases our life expectancy has been around for decades and forms the basis for a book called The Longevity Diet by Brian Delaney and Lisa Walford. As far back as the 1930’s, an American scientist found that drastically reducing the calories fed to mice helped them to live longer and be healthier. In more recent times, the same thing has been shown in a variety of life forms including fruit flies, roundworms and monkeys.

The idea of severely restricting calories every other day – rather than every day – to improve health and life expectancy came in 2003 following laboratory research carried out at the 1National Institute on Ageing in America.

After 20 weeks, mice who were allowed to eat as much as they wanted on one day but not fed the next day, lived longer and had lower levels of glucose and insulin and improved insulin sensitivity compared to mice that were allowed to eat freely all of the time. But more importantly, these levels matched or were even better than those of mice who ate 40 percent fewer calories than normal every day. The scientists involved in the study concluded that alternate day fasting was just as likely to improve health and life expectancy as a daily calorie restriction.

(Video) Could the trendy alternate-day fasting diet be putting you in danger?

Is there any evidence that the same thing happens in humans?

To date, most research has been carried out in laboratories with animals. There aren’t many human studies that have looked at the link between restricting calories and life expectancy – and even fewer that specifically look at the impact of alternate day fasting on health and longevity. Those human studies that have been carried out have generally had several limitations – namely that they include only a few participants and have only been carried out over a short period of time. It’s an area that needs a lot more research before any definite conclusions can be drawn.

So what’s the link with weight loss?

Unsurprisingly, restricting calories – whether it’s all of the time or fasting every other day – usually results in weight loss. The concept of an eating pattern that alternates between periods of fasting followed by periods of eating is sometimes known as Intermittent Fasting. When this pattern follows a 24-hour fast followed by a 24-hour feast, it’s sometimes called Alternate Day Fasting.

One small human study published in the 2American Journal of Clinical Nutrition has shown how alternate day fasting can aid weight loss. In this study, 16 normal weight adults followed an alternate day fasting regime for three weeks. On fasting days they had nothing but calorie-free drinks whilst on feasting days they were allowed to eat whatever they wanted. At the end of the study, the adults had:

  • Lost an average of 2.5 percent of their initial body weight
  • Lost four percent of their fat mass

This indicates that they didn’t consume two days worth of calories on feasting days to make up for the lack of calories on the day of fasting.

However, most participants felt extremely hungry throughout the study and said they couldn’t sustain this type of eating pattern for long. The scientists behind the study suggested that allowing one small meal on a fasting day might make the diet more acceptable. And that’s exactly what the Alternate-Day Diet is based on. Rather than totally fasting on alternate days, the idea is to severely restrict calories to 20 percent – or just one fifth – of your normal calorie intake.

So how do I follow the Alternate Day Fasting diet?

On the first day of the diet, you have just one fifth of you normal calorie intake that keeps your weight steady. As a guideline, women need around 2,000 calories a day, and men 2,500 calories a day for weight maintenance. This means on a ‘fasting’ day – when you are allowed just one fifth of this – women should have 400 calories and men, 500 calories. However, the heavier you are, the more calories you need just to keep your weight steady.

You can get a more accurate picture of how many calories you need for weight maintenance by entering your weight, height and sex into the personal information on Weight Loss Resources database. Then divide this figure by five to calculate the amount of calories you should have on a ‘fasting’ day.

To make it easier to stick to such a low calorie intake on fasting days, the Alternate-Day Diet recommends sipping ready-made meal replacement shakes that add up to your ‘fasting’ daily calorie allowance. These have the advantage of being fortified with nutrients and help to remove the temptation to overeat. On the second day of the diet, you simply eat what you would normally eat. Then on day three, you do the same as on day one – and so on.

After two weeks on this regime, you should start eating food rather than meal replacement products on ‘fasting’ days. Ideally, you should stick to 20 percent of your usual calorie intake. However, if you find this too restrictive it’s acceptable to increase to 25-35 percent of your usual intake. For women that’s around 500-700 calories a day (based on a usual intake of 2,000 calories); for men it’s 625-875 calories a day (based on a usual intake of 2,500 calories).

How much weight loss can I expect?

The author of the Alternate-Day Diet lost 35lb in 11 weeks – an average of around 3lb a week. However, on average, you can expect to lose around 1-2lb a week, with perhaps a few extra pounds in the first week as your body adapts. This is highlighted by a small study of 12 obese women and four obese men, who, after following a similar intermittent fasting diet, showed:

(Video) Eat, Fast, Lose? New book suggests alternate day fasting

  • An average weight loss of 12lb after eight weeks, equating to 1.5lb a week
  • A drop in body fat from 45 to 42 percent in participants
  • A reduction in blood pressure, total cholesterol and LDL (or ‘bad’) cholesterol.

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How often should I weigh myself?

Only weigh yourself at 6 or 8-day intervals, preferably in the morning after a fast day. This is because you can see a variation of as much as 3-4lb between a feast and fast day.

So is weight loss purely down to an overall calorie reduction?

According to the author of the Alternate-Day Diet this isn’t the case. Certainly, a total calorie reduction through fasting aids weight loss. However, this approach is based on the idea that fasting every other day also activates a ‘skinny’ gene called SIRT1 that helps to boost weight loss further and adds to the health benefits of such a diet.

What else can you tell me about this skinny gene?

The way SIRT1 works is complicated. The theory goes that when cells are restricted of energy – as is the case when we have a very low calorie intake – they become ‘stressed’ and start to die. This is thought to trigger a chain of events that activates SIRT1, which in turn sets off a process that stops cells from dying.

This skinny gene is thought to help make our metabolism more efficient so that we burn fat more effectively and also helps to inhibit fat storage. Plus, SIRT1 has been shown to inhibit substances in our bodies that can cause inflammation. This is important because inflammation is thought to be at the root of many health problems including:

  • heart diseases
  • cancer
  • premature ageing
  • asthma
  • arthritis
  • Alzheimer’s disease

It’s thought this may be the reason why animal research shows that restricting calories improves health.

Can anyone follow this diet?

It’s always worth checking with your doctor before starting a new diet. However, very low calorie intakes on alternate days may not be suitable for some people, for example, people with diabetes. Eating very little on certain days may also not be suitable if you take certain medications. To be sure, it’s best to see your doctor and discuss the diet.

What are the pros of Alternate Day Fasting?

Ultimately, this intermittent fasting plan can reduce your overall calorie content to help you lose weight. You may also feel less deprived on a plan like this as you’re dealing with ‘dieting chunks’ that last for just 24 hours at a time. It also enables you to eat normally at social occasions, taking away the worry about trying to choose low calorie options.

This type of eating pattern may also help to prevent metabolism from slowing down, which inevitably occurs when calories are restricted. Your body doesn’t perceive it’s starving – which is what happens with a constant low calorie intake – so the mechanism that kicks in to slow down your metabolism in order to save calories doesn’t get switched on. This type of eating pattern is simply a far more extreme version of what nutritionists and dietitians often recommend – compensating for a day of overindulging with a day of being strict.

(Video) Alternate Day Fasting - The Basics

And the cons of Alternate Day Fasting?

There’s always the possibility you may end up bingeing on the ‘feast’ days, as you’re so hungry after a fasting day. Research with mice found that alternate day fasting didn’t result in weight loss as the rodents simply gorged themselves on the days when they were able to eat, easily compensating for all the calories they had saved by fasting ever other day.

This is easier to do than you might think, too. For example, with this diet, a woman who normally needs 2,000 calories a day to maintain her weight would alternate between having 400 calories on one day and 2,000 calories the next – giving a total of 2,400 calories over the two days instead of the normal 4,000 calories.

However, having a chicken korma with pilau rice, a naan bread, a couple of poppadoms with chutney and two large glasses of wine alone contains around 2,300 calories. Add this to a normal 400-calorie breakfast, a normal 600-calorie lunch, 300 calories worth of snacks plus 400 calories on a ‘fasting’ day and your calorie intake over the two days is 4,000 calories – the same as you’d normally eat, therefore totally undoing the calorie savings of a fasting day.

You’re also likely to come unstuck if your ‘normal’ diet isn’t that healthy and you continue with this type of eating on non-fasting days. And there’s the potential for us to end up with an unhealthy diet that’s lacking in nutrients, particularly if you don’t follow the principles of healthy eating on the days when we can eat. Finally, there’s the very real problem of dealing with extreme hunger on fasting days.

Juliette’s verdict

The idea of eating what you want every other day certainly sounds attractive – but of course it comes with payback – and that’s practically starving yourself on the alternate days! Nevertheless, this type of eating pattern may work for some. Effectively, it’s simply a new way to help you take in potentially fewer calories than you burn up so that you use up your fat stores and lose weight as a result.

However, for the plan to really work, it’s crucial that on the days when you do eat, you don’t go mad and gorge yourself. Spend these days eating biscuits, cakes, fried food, sugary drinks, crisps and chocolate and you won’t get the benefits of the fasting days. It’s also important to make sure that the foods you do eat are packed with nutrients to help top up intakes of protein, vitamins , minerals and fibre – the downside of eating roughly half as much as normal means you’re likely to miss out on half the nutrients you’d normally get.

This means ‘feasting’ days should consist of plenty of fruit, veg, wholegrains, pulses, lower-fat dairy products and lower-fat protein-rich foods such as lean red meat, poultry, fish and eggs. Knowing you need to be less rigid in what you eat the next day may help to avoid feelings of deprivation, which tend to be more common when following a restricted diet for weeks on end. This can help to keep you motivated.

Whether or not alternate day fasting really does offer major health benefits and increase life expectancy remains a matter of debate. There’s simply not been enough well-designed, long-term studies in humans to reach the conclusion that restricting calories helps us to live longer. Indeed, it’s a big jump to suggest that what we see in mice will also be seen in men!

What we do know though, without a shadow of doubt, is that losing weight is one of the most important things we can do to improve our health and life expectancy. A recent analysis of 57 long-term studies found that obesity seriously reduces our life span – people who are very obese can expect to knock 10 years of their life. That’s similar to someone who has spent a lifetime smoking. Huge amounts of research have proven that being overweight increases our risk of many health problems including heart disease, stroke, high blood pressure, certain cancers, type 2 diabetes and, in turn, many of these conditions are known to reduce the number of years we are expected to live.

Bottom line: if you want to live longer and stay healthy, losing weight, if necessary, will help. The key is to find an eating plan that suits you and your lifestyle – and if you like the sound of the Alternate-Day Diet then it might be worth giving it a go to kick start a longer-term healthy eating plan.

(Video) Intermittent Fasting - How it Works? Animation

Typical Fast Day (529 calories)


1 slice wholegrain toast with 1tbsp peanut butter


Bowl of Asian chicken noodle soup made from chicken broth, courgette, peppers, spring onions, a little cooked chicken breast, a small amount of noodles and hot pepper sauce.


Turkey chilli made from a little minced turkey, garlic, pepper, chilli, canned tomatoes, white beans e.g. cannellini, spices and herbs.


1 National Institute of Aging-RM Anson, Z Guo, R de Cabo, T Iyun, M Rios, A Hagepanos, DK Ingram, MA Lane, MP Mattson, "Intermittent fasting dissociates beneficial effects of dietary restriction on glucose metabolism and neuronal resistance to injury from caloric intake," Proceedings of the National Academy of Sciences Online Early Edition the week of April 28, 2003

2 American Journal of Clinical Nutrition -Leonie K Heilbronn, Steven R Smith, Corby K Martin, Stephen D Anton, and Eric Ravussin"Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism1,2"© 2005 American Society for Clinical Nutrition

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Is alternate day fasting 24 or 36 hours? ›

It's called alternate-day fasting (ADF). Essentially, alternate-day fasting is when you avoid food (zero caloric intake) for 36 hours. Yes, it's pretty hardcore. For example with intermittent fasting, you may only go 16 hours without food.

How many calories should I eat on ADF? ›

Strict ADF prohibits taking in any calories whatsoever on fasting days. While the most liberal forms of ADF don't allow intake of more than 500 calories per fasting day.

How many kgs can I lose with alternate day fasting? ›

Studies have found that alternate-day fasting can make one lose 4.5 to 6 kilos of weight in three months, which is more than what's seen with other intermittent fasting regimens that limit eating periods to a certain window each day.

How long does it take to get used to alternate day fasting? ›

Mattson's research shows that it can take two to four weeks before the body becomes accustomed to intermittent fasting. You might feel hungry or cranky while you're getting used to the new routine.

How effective is alternate day fasting? ›

Alternate-day fasting and weight loss

Studies among adults with overweight and obesity show that engaging in ADF may help you lose 3–8% of your body weight in 2–12 weeks. Research suggests that this method is not superior to traditional daily calorie restriction for promoting weight loss ( 3 , 6 , 8 , 9 , 10 ).

Does a 36 hour fast do anything? ›

According to research, periodic fasting, such as doing a 36 hour water fast once a week, alters the metabolism and supports weight loss through three primary ways: altering your circadian biology, modifying your gut microbiome, and you shift modifiable lifestyle behaviors such as your sleep patterns and energy intake.

Is 1200 calories a day restrictive? ›

A 1,200-calorie diet is much too low for most people and can result in negative side effects like dizziness, extreme hunger, nausea, micronutrient deficiencies, fatigue, headaches, and gallstones ( 23 ). Furthermore, a 1,200-calorie diet can set you up for failure if long-term weight loss is your goal.

What happens if I only eat every other day? ›

A new research study published in Cell Metabolism suggests that for healthy, non-obese adults, not only is eating every other day safe to practice for at least several months, but it also has weight loss, general health and potential anti-aging benefits.

Does ADF slow metabolism? ›

“With alternate day fasting, you are more than likely taking in the same amount of calories over a two-day period, and your metabolism is around the same.” The researchers also reported that more members of the ADF group dropped out of the study.

How much weight can you lose in 6 months with alternate day fasting? ›

In doing the fast correctly and ensuring that it is aligning with your mind, body and soul–you can expect a good weight loss of anywhere between 2 to 6 kgs a month with excellent inch loss and increase in energy levels and brain function.

How can I lose 2kg a week on intermittent fasting? ›

You should aim for 10,000 to 12,000 steps per day, but remember diet is key to losing weight. Can I lose 2kg a week with intermittent fasting? Yes. Typically people chose a period of time during the day that you will fast which will last 16 to 20 hours.

How can I lose 20 kg in a month? ›

For reducing weight follow three main things like healthy diet, exercise and brisk walk morning and evening which increase ur metabolism. Take high fiber food in ur diet. Add more fruits and vegetables in ur diet. Add plenty of water.

What not to do after fasting? ›

Breaking your fast with foods that are especially high in fat, sugar, or even fiber can be difficult for your body to digest, leading to bloating and discomfort. Foods and drinks that can be even more shocking to your system after a fast include those like a greasy cheeseburger, slice of cake, or soda.

Can I fast from 7pm to 11am? ›

How fasting and eating is divided each day is called an eating schedule. One of the most common, easy-to-follow schedules is 16:8. This means you fast for a 16-hour period of time and eat your daily meals during an 8-hour period of time. For example, you may want to fast from 7 p.m. until 11 a.m. the next day.

Does your stomach shrink when fasting? ›

Myth or Fact: If you cut down on your food intake, you'll eventually shrink your stomach so you won't be as hungry. Answer: Myth. Once you are an adult, your stomach pretty much remains the same size -- unless you have surgery to intentionally make it smaller.

Does alternate day fasting reduce inflammation? ›

One study found that fasting for more than 24 hours lowered inflammation by reducing oxidative stress in the cells. Another study found that both intermittent fasting and alternate-day fasting were both effective at reducing insulin resistance, which is the precursor to type 2 diabetes (an inflammatory condition).

Which is better intermittent fasting or alternate day fasting? ›

“Alternate day fasting produces faster weight loss, about 10 to 15 pounds in three months, compared with time-restricted feeding,” says Varady. “But it's harder to follow because you have to count calories every other day.”

Is a 24 hour fast once a week healthy? ›

New research finds that fasting for 24 hours once or twice a week is associated with improved metabolic health. Experts say the body is designed to need a break from eating to rest and repair itself.

What should I do after a 36 hour fast? ›

The 36 Hour Fast also requires some planning when considering what to eat after a 36 hour fast. It's recommended that you break your fast with a very light meal, then let that digest prior to eating normally again.

Will a 36 hour fast put me in ketosis? ›

The Monk Fast involves drinking only water and other calorie-free drinks like black coffee or tea for 36 hours once per week. This causes your body to enter ketosis, a metabolic state in which your body breaks down and uses fat for energy instead of sugar ( 1 ).

How much weight is lost in a 36 hour fast? ›

For every 36 hour fast, we should expect to lose about half a pound of body fat. Anything beyond that is typically water loss. At the start, women experience significantly less than that.

How do I know if my body is in starvation mode? ›

Here are nine signs that you're not eating enough.
  1. Low Energy Levels. Calories are units of energy your body uses to function. ...
  2. Hair Loss. Losing hair can be very distressing. ...
  3. Constant Hunger. ...
  4. Problems Trying to Get Pregnant. ...
  5. Sleep Issues. ...
  6. Irritability. ...
  7. Feeling Cold All the Time. ...
  8. Constipation.

What is the minimum calories per day for a woman? ›

However, calorie intake should not fall below 1,200 a day in women or 1,500 a day in men, except under the supervision of a health professional. Eating too few calories can endanger your health by depriving you of needed nutrients.

How little calories is too little? ›

As a general rule, people need a minimum of 1,200 calories daily to stay healthy. People who have a strenuous fitness routine or perform many daily activities need more calories. If you have reduced your calorie intake below 1,200 calories a day, you could be hurting your body in addition to your weight-loss plans.

How long does it take for autophagy to start? ›

How long do you have to fast for autophagy to occur? Studies involving animals suggest that autophagy may begin between 24 to 48 hours of fasting. Not enough research has been collected on the ideal timing to trigger human autophagy.

Is fasting 3 days a week healthy? ›

No, it is not. Whether you are looking for potential health benefits or as a way to jumpstart your weight loss, water fasting for 3 days is truly not the way to go about it. This is a very unhealthy and potentially fatal way to try living a healthier life.

What is a good fasting schedule? ›

Fast for 12 hours a day

According to some researchers, fasting for 10–16 hours can cause the body to turn its fat stores into energy, which releases ketones into the bloodstream. This should encourage weight loss. This type of intermittent fasting plan may be a good option for beginners.

What are 3 things that slow down your metabolism? ›

Here are 6 lifestyle mistakes that can slow down your metabolism.
  • Eating too few calories. Eating too few calories can cause a major decrease in metabolism. ...
  • Skimping on protein. ...
  • Not getting enough high-quality sleep. ...
  • A lack of strength training.

Which body type has the slowest metabolism? ›

Endomorphs have the slowest metabolic rate of all the body types. Do not tolerate carbohydrates well (not that they should be avoided completely of course). Endomorphs have lots of muscle already and tend to hold on to it easily. They also can build muscle easily.

Can you exercise on ADF? ›

Previous reports indicate that ADF is an effective strategy to reduce body weight (5% in 12 weeks) and improve body composition. More recently, it has been shown that combining ADF with exercise leads to greater weight loss (7% in 12 weeks) than what has been seen with ADF or exercise alone [2].

How much weight can you lose in 4 weeks with intermittent fasting? ›

Another study found that participants consumed 35% fewer calories and lost an average of 7.7 pounds (3.5 kg) after alternating between 36 hours of fasting and 12 hours of unlimited eating over 4 weeks (12). If you really want to maximize weight loss, adding an exercise regime to your life can help.

What can I drink while fasting? ›

Technically speaking, eating or drinking any calories breaks a fast. That means it's generally considered OK to drink black, unsweetened coffee or tea, as well as water.

How much weight can I lose in 2 weeks intermittent fasting? ›

Like many diets, you need to remain consistent and make lifestyle changes to get results. It might take a few weeks for you to drop your first pound from intermittent fasting. However, once you start, you can expect to lose about a pound each week. Some people can lose up to 10 pounds each month.

Why am I gaining weight while intermittent fasting? ›


You'll be so hungry, you may start eating and not stop. As well, the body stores food to protect itself. Your body will sense the need to stock up on reserves and may store those extra pounds as fat instead of lean muscle.

How can I shred 5kg in 2 weeks? ›

Five tips to help you lose five kilos in two weeks
  1. Eat lots of green vegetables or a fibre supplement. ...
  2. Limit alcohol to four standard drinks a week. ...
  3. Your body converts wheat to sugar faster than any other grain. ...
  4. One coffee per day is allowed.
2 Nov 2020

How can I lose 5kg in a week with intermittent fasting? ›

You can try doing intermittent fasting. To do this, fast for 16 hours, then eat healthy meals during your 8 hour feeding period. Choose lean meats or fish, non-starchy vegetables, healthy fats, and fruit. If this diet interests you, look for tips online to help you do it right.

What is dry fasting? ›

Dry fasting is just an extreme version of fasting which involves restricting food as well as water intake. This pattern of eating is claimed to aid weight loss, build immunity and improve mental well-being.

How much should I walk daily to lose 20 kg? ›

Dieting does not burn fat, so sufficient physical exercise is important. As you have very long working hours, you need to make sure you squeeze in 30 minutes for a brisk walk every day. If you have to travel very short distances, walk. You need to walk at least five days a week.

How can I lose 5kg in a week? ›

You can further lose up to five kgs in a week by following a calorie deficit diet, though experts suggest that it is best to target losing 1-2kgs per week. The key is to keep the body in fat-burning mode with the combination of restrictive eating and increased physical activity.

Is OMAD the same as 24 hour fast? ›

However, the OMAD is really just an extreme variant of intermittent fasting or a more hardcore cousin of the Warrior Diet. The difference between OMAD and traditional fasting is instead of fasting for the typical window, like 16 hours, you fast for about 23 hours (including the time you spend sleeping).

How often should I fast for 36 hours? ›

The Monk Fast calls for 36 hours of complete fasting roughly once a week. During this fasting period zero calorie consumption is permitted — though subscribers of the diet are allowed to enjoy flavored water, coffee, and tea.

What counts as 24 hour fast? ›

A weekly 24-hour fast

Fasting completely for 1 or 2 days a week, known as the Eat-Stop-Eat diet, involves eating no food for 24 hours at a time. Many people fast from breakfast to breakfast or lunch to lunch. People on this diet plan can have water, tea, and other calorie-free drinks during the fasting period.

What is a 36 12 fasting schedule? ›

The most popular style of ADF is the 36:12 method. For the 36:12 method, you eat breakfast when you wake up, then consume all other meals within a 12-hour window. You then proceed to fast for 36 hours until the next feeding time.

What are the drawbacks of the OMAD diet? ›

The Cons
  • It can be difficult to sustain. Intermittent fasting regimens like OMAD have a dropout rate of up to 65%. ...
  • It may make you hungrier. When you eat one meal a day rather than three, your body produces more of a hormone called ghrelin, which makes you feel hungry.
  • It's no more effective than calorie reduction.
8 Apr 2021

Why am I gaining weight when I barely eat? ›

Unintentional weight gain occurs when you put on weight without increasing your consumption of food or liquid and without decreasing your activity. This occurs when you're not trying to gain weight. It's often due to fluid retention, abnormal growths, constipation, or pregnancy.

Is it better to fast for 16 or 24 hours? ›

But according to the information above, in terms of insulin level, the fast is only really getting going at 16 hours. Extending it further than this ramps the drop in insulin and the increase in lipolysis. If you can extend your fast into the afternoon, you get more benefits, and a 24-hour fast would do even more.

What happens to your body after a 36 hour fast? ›

When you fast for 36 hours or more, you enter into the realm of extended fasting. The benefits of this practice include weight loss, lower blood sugar, ketosis, and enhanced autophagy. To help your body adapt to using body fat for energy, start with shorter fasts and work your way up to longer fasts.

What happens to the body after 48 hours of fasting? ›

Fasting for 48 hours may boost your health by promoting weight loss, improving insulin sensitivity, and reducing inflammation. It may also help you live longer by delaying cell aging.

Does coffee break a fast? ›

The short answer is yes, you can drink coffee while intermittent fasting. But, this answer comes with a big caveat: You can drink black coffee while intermittent fasting, but coffee drinks with cream, sugar, or other forms of calories technically break your fast.

Is it better to fast for 12 or 16 hours? ›

For example, studies have found that people who regularly fast more than 16 or 18 hours a day have a higher risk of gallstones. They're also more likely to need surgery to remove the gallbladder. Eating for 12 hours and then fasting for 12 hours is likely safe for most people, Longo explains.

Does sleeping count as fasting? ›

Does sleeping count as fasting? A. Yes, while following intermittent fasting, sleeping is considered a fasting period. Therefore, one does not consume food or drinks during this state.

Can I do a 36 hour fast once a week? ›

One of the easiest to implement is the 36-hour fast once a week. Also known as Monk Fasting, the 36-hour fast simply involves taking a day off from eating every week. Many people have had great success with this approach, while others say that it is too extreme.

Is 12 hour fasting window enough? ›

A good rule of thumb for those wanting to fast to improve their metabolic and overall health is to leave at least 12 hours between meals – ideally more – on a regular basis, according to Dr Adam Collins, Principal Teaching Fellow in Nutrition at the University of Surrey.


1. 30 Days of Alternate-Day Fasting - 10lbs of Body Fat (Before & After)
(Goal Guys)
2. Alternate Day Fasting for 3 months transformation - Worth it?
(Alan Grandman)
3. 3 Ways to Do Alternate Day Fasting
(Dr. Becky Gillaspy)
4. Dr. Oz Explains Intermittent Fasting | TODAY
5. Intermittent Fasting: Handle Your Health Problems The Natural Way
6. What is intermittent fasting? Scientific take on 5:2 and 16:8 diets
(ABC Science)
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