6 ways to do intermittent fasting

6 methods of intermittent fasting

There are various methods of intermittent fasting, and people will prefer different styles. Read on to find out about six different ways to do intermittent fasting.

1. Fasting for 12 hours a day

The rules for this diet are simple. A person needs to decide on and adhere to a 12-hour fasting window every day.

According to some researchers, fasting for 12 to 14 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 suitable option for beginners. This is because the fasting window is relatively small, much of the fasting occurs during sleep, and the person can consume the same number of calories each day.

The easiest way to follow the 12-hour fast is to include the period of sleep in the fasting window.

For example, a person could choose to fast between 7 p.m. and 7 a.m. They would need to finish their evening meal before 7 p.m. and wait until 7 a.m. to eat breakfast but would be asleep for much of the time in between.

2. Fasting for 16 hours

Fasting for 16 hours a day, leaving an 8-hour eating window, is called the 16:8 method or the Leangains diet.

Some experts may recommend females fast for 14 hours and slowly build their way up to 16 hours, while males can start fasting for 16 hours straight away.

This type of intermittent fast may be helpful for someone who has already tried the 12-hour fast but did not experience any benefits.

On this fast, people usually finish their evening meal by 8 p.m. and skip breakfast the next day, not eating again until noon.

A 2022 review found that this fasting method, alongside calorie restriction, may be beneficial for weight management in adults with overweight or obesity and may have a positive effect on blood sugar processing.

3. Fasting for 2 days a week

People following the 5:2 diet eat standard amounts of healthful food for 5 days and reduce calorie intake on the other 2 days.

During the 2 fasting days, men generally consume 600 calories and women 500 calories.

Typically, people separate their fasting days in the week. For example, they may fast on a Monday and Thursday and eat regularly on the other days. There should be at least 1 nonfasting day between fasting days.

There is limited research on the 5:2 diet, which is also known as the Fast diet.

A 2022 study examining different types of fasting found that the 5:2 diet had no clear ranking when compared with the other intermittent fasting regimens.

A 2021 randomized controlled trial found that adults with obesity who tried the 5:2 fasting method with group support experienced a greater weight loss at 6 weeks and rated the diet highly.

However, the effect of weight loss diminished over time, with the weight difference no longer being significant by 1 year.

4. Alternate day fasting

There are several variations of the alternate day fasting plan, which involves fasting every other day.

For some people, alternate day fasting means a complete avoidance of solid foods on fasting days, while other people allow up to 500 calories. On feeding days, people often choose to eat as much as they want.

Alternate day fasting is an extreme form of intermittent fasting, and it may not be suitable for beginners or those with certain medical conditions. It may also be difficult to maintain this type of fasting in the long term.

5. 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 following this diet plan can have water, tea, and other calorie-free drinks during the fasting period.

People should return to regular eating patterns on nonfasting days. Eating in this way reduces a person’s total calorie intake but does not limit the specific foods the individual consumes.

A 24-hour fast can be challenging and may cause fatigue, headaches, or irritability. Many people find these effects become less extreme over time as their bodies adjust to this new eating pattern.

People may benefit from trying a 12-hour or 16-hour fast before transitioning to the 24-hour fast.

6. The Warrior Diet

The Warrior Diet is a relatively extreme form of intermittent fasting.

It involves eating very little, usually just a few servings of raw fruit and vegetables, during a 20-hour fasting window, then eating one large meal at night. The eating window is usually only around 4 hours.

This form of fasting may be best for people who have tried other forms of intermittent fasting already.

Supporters of the Warrior Diet claim that humans are natural nocturnal eaters and that eating at night allows the body to gain nutrients in line with its circadian rhythms.

During the 4-hour eating phase, people should make sure they consume plenty of vegetables, proteins, and healthy fats. They should also include some carbohydrates.

Although it is possible to eat some foods during the fasting period, it can be challenging to stick to strict guidelines on when and what to eat in the long term. Some people may also have difficulty eating such a large meal so close to bedtime.

There is also a risk that people on this diet will not eat enough nutrients, such as fiber. This can increase the risk of cancer and have an adverse effect on digestive and immune health.

Other tips for intermittent fasting

It can be challenging to stick to an intermittent fasting program.

The following tips may help people stay on track and maximize the benefits of intermittent fasting:

• Staying hydrated: Drink lots of water and calorie-free drinks, such as herbal teas, throughout the day. This can help ensure you get enough electrolytes, sodium, and potassium chloride.
• Avoiding thinking about food: Plan plenty of distractions on fasting days to avoid thinking about food, such as catching up on paperwork or going to see a movie.
• Resting and relaxing: Avoid strenuous activities on fasting days, although light exercise such as yoga may be beneficial.
• Making every calorie count: If the chosen plan allows some calories during fasting periods, select nutrient-dense foods that are rich in protein, fiber, and healthful fats. Examples include beans, lentils, eggs, fish, nuts, avocado, and unprocessed meats.
• Eating high volume foods: Select filling yet low calorie foods, which include popcorn, raw vegetables, and fruits with high water content, such as grapes and melon.
• Increasing the taste without the calories: Season meals generously with garlic, herbs, spices, or vinegar. These foods are extremely low in calories yet are full of flavor.
• Choosing nutrient-dense foods after the fasting period: Eating foods that are high in fiber, vitamins, minerals, and other nutrients helps to keep blood sugar levels steady and prevent nutrient deficiencies. A balanced diet will also contribute to weight loss and overall health.

Are there risks of intermittent fasting?

Recent research from the American Heart Association (AHA) has suggested a link between intermittent fasting and cardiovascular disease.

One 2024 study involving over 20,000 adults from across the United States found that people who restricted their eating to an 8-hour eating schedule — otherwise known as the 16:8 method — had a 91% higher risk of death from cardiovascular disease.

Researchers from Shanghai Jiao Tong University in China presented these findings at an AHA conference.

However, it is important to note that the study was observational, so it does not show cause and effect, only a link between two factors.

This study does not show whether time-restricted eating itself increases the risk of cardiovascular death. Nor does it show whether those who are more likely to die from cardiovascular-related illness might also be more likely to be on a time-restricted diet.

Another thing to note is that these findings have not been published in a peer-reviewed journal, so have not gone through the peer-review process.

Most research shows that time-restricted eating is beneficial for health, particularly in those with overweight and obesity.

However, these dietary approaches may not be suitable for everyone. For example, if someone has a history of disordered eating, intermittent fasting may exacerbate their atypical relationship with food.

It is also important for people with health conditions such as diabetes to consult a healthcare professional before fasting.

Frequently asked questions

Below are some common questions about intermittent fasting.

How does intermittent fasting work for beginners?

People starting intermittent fasting for the first time may find the 12-hour fasting method the easiest. This involves fasting for 12 hours every 24-hour period.

People can include the time when they are asleep in this fasting window, for example, fasting from 7 p.m. to 7 a.m.

How much weight can someone lose in a month with intermittent fasting?

The amount of weight someone can lose with intermittent fasting depends on various factors, including the type and duration of fasting, their current weight, and how many calories they consume when they are not fasting.

A 2023 meta-analysis states that alternate day fasting, 5:2 fasting, and time-restricted eating can cause weight loss reductions of 1% to 13% over 2 to 52 weeks.

Is it better to fast for 12 or 16 hours?

The effectiveness of different fasting methods may vary between people. Fasting for 16 hours may be effective for people who did not experience results when fasting for 12 hours.

How many days can someone do intermittent fasting?

Some fasting practices may involve fasting for 1 day a week, every other day, or 2 days a week. People should speak with a healthcare professional to ensure they are staying safe when fasting.

Summary

There are many ways to do intermittent fasting, and no single plan will work for everyone. Individuals will experience the best results if they the various styles to learn what suits their lifestyles and preferences.

Regardless of the type of intermittent fasting, fasting for extended periods when the body is unprepared can be problematic.

These forms of dieting may not be suitable for everyone. If a person is prone to disordered eating, these approaches may exacerbate their irregular relationship with food.

People with health conditions, including diabetes, should speak with a doctor before attempting any form of fasting.

For the best results, it is essential to eat a healthful and balanced diet on nonfasting days. If necessary, a person can seek professional help to personalize an intermittent fasting plan and avoid pitfalls.

People can contact a registered dietitian to help them choose the most suitable approach for intermediate fasting that fits their lifestyle.

Learn more in this ultimate beginner’s guide to intermittent fasting.

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