The 16:8 intermittent fasting plan is a form of time-restricted fasting that may help with weight loss. It involves fasting for 16 hours per day and consuming all calories during the remaining 8 hours.

Suggested benefits of the 16:8 plan include weight loss and fat loss, as well as the prevention of type 2 diabetes and other obesity-associated conditions.

Read on to learn more about 16:8 intermittent fasting, including how to do it and the health benefits and side effects.

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The 16:8 intermittent fasting plan is a form of time-restricted fasting. It involves consuming foods during an 8-hour window and avoiding food, or fasting, for the remaining 16 hours each day.

Some people believe that this method works by supporting the body’s circadian rhythm, which is its internal clock.

Most people who follow the 16:8 plan abstain from food at night and for part of the morning and evening. They tend to consume their daily calories during the middle of the day.

There are no restrictions on the types or amounts of food that a person can eat during the 8-hour window. This flexibility makes the plan relatively easy to follow.

Read on to learn more about other methods of intermittent fasting.

The easiest way to follow the 16:8 diet is to choose a 16-hour fasting window that includes the time a person spends sleeping.

Some experts advise finishing food consumption in the early evening, as metabolism slows down after this time. However, this is not feasible for everyone. It is also advisable to avoid food for 2–3 hours before bed.

People may choose one of the following 8-hour eating windows:

  • 9 a.m. to 5 p.m.
  • 10 a.m. to 6 p.m.
  • noon to 8 p.m.

Within this timeframe, people can eat their meals and snacks at convenient times. Eating regularly is important to prevent blood sugar peaks and dips and to avoid excessive hunger.

Some people may need to experiment to find the best eating window and mealtimes for their lifestyle.

While the 16:8 intermittent fasting plan does not specify which foods to eat and avoid, it is beneficial to focus on eating nutritious foods and limiting or avoiding junk foods.

A balanced diet focuses primarily on:

  • fruits and vegetables, which can be fresh, frozen, or canned
  • whole grains, including quinoa, brown rice, oats, and barley
  • lean protein sources, such as poultry, fish, beans, lentils, tofu, nuts, seeds, low fat cottage cheese, and eggs
  • healthy fats from fatty fish, olives, olive oil, coconuts, avocados, nuts, and seeds

Fruits, vegetables, and whole grains are high in fiber, so they can help keep a person feeling full and satisfied. Healthy fats and proteins can also contribute to satiety.

Beverages can play a role in satiety for those following the 16:8 intermittent fasting diet. Other fasting methods emphasize the importance of drinking water regularly throughout the day.

Maintaining hydration, through the consumption of calorie-free drinks, such as water and unsweetened tea and coffee, will also help avoid dehydration.


People may find it easier to stick to the 16:8 intermittent fasting plan when they try:

  • consuming water regularly throughout the day
  • infusing water with lemon, lime, or cucumber to make it easier to drink
  • watching less television to reduce exposure to images of food, which may stimulate a sense of hunger
  • performing aerobic exercise, which may help suppress appetite in some individuals
  • practicing mindful or intuitive eating when consuming meals
  • trying meditation during the fasting period to allow hunger pangs to pass

Research on intermittent fasting, including 16:8 fasting, indicates that it may provide the following benefits:

Weight loss and fat loss

Eating during a set period can help people reduce the number of calories that they consume. It may also help boost metabolism.

A 2023 systematic review and meta-analysis states that intermittent fasting alongside calorie restriction can be an effective method for promoting weight loss.

Similarly, a 2020 systematic review notes that forms of intermittent fasting, such as 16:8 fasting, show promise for the treatment of obesity. However, the review also adds that more long-term research into intermittent fasting is necessary to confirm its possible benefits.

Disease risk reduction

Supporters of intermittent fasting suggest that it can reduce the risk of several conditions and diseases. For example, a 2023 article suggests it can help decrease the risk of:

Some evidence suggests that time-restricted fasting may help with managing metabolic conditions. Aligning when a person eats with their internal body clock may help optimize health and reduce the risk of conditions such as diabetes, heart disease, and liver disease.

However, a 2023 meta-analysis indicates that intermittent fasting does not influence blood glucose or blood pressure.

Extended life span

A 2023 article suggests that intermittent fasting, such as 16:8 fasting, may help increase life span and promote a higher quality of life. However, the authors note that there are no long-term studies that show any cause and effect for fasting and aging or longevity.

The National Institute on Aging points out that, even after decades of research, scientists still cannot explain why fasting may lengthen life span. As a result, they cannot confirm the long-term safety of this practice.

Human studies in the area are limited, and the potential benefits of intermittent fasting for human longevity are not yet known. As such, more research is necessary.

The 16:8 intermittent fasting plan has some associated risks and side effects. As a result, the plan is not right for everyone. Potential side effects and risks may include:

  • feeling unwell and experiencing headaches, lethargy, crankiness, and constipation
  • excessive weight loss in older adults
  • overeating or eating unhealthy foods during the 8-hour eating window due to excessive hunger
  • harm to individuals living with certain health conditions or taking certain medications

Individuals with a history of disordered eating may wish to avoid intermittent fasting. The National Eating Disorders Association warns that fasting is a risk factor for eating disorders.

The National Institute on Aging concludes that there is insufficient evidence to recommend any fasting diet, especially for older adults.

The 16:8 intermittent fasting plan is unsuitable for those who are pregnant, breastfeeding, or trying to conceive.

People who wish to try the 16:8 method or other types of intermittent fasting should talk with their doctor first, especially if they:

  • have an underlying health condition, such as diabetes or low blood pressure
  • take medications for blood pressure or heart disease
  • have a history of disordered eating

Anyone who has any concerns or experiences any adverse effects of the diet should consult a doctor.

While evidence indicates that the 16:8 method may be helpful for diabetes prevention, it may not be suitable for those who already have the condition.

The 16:8 intermittent fasting diet is generally not suitable for people with type 1 diabetes. Additionally, many forms of religious fasting list type 1 diabetes as an exemption due to the potential health risks.

However, some people with prediabetes or type 2 diabetes may be able to try the diet under a doctor’s supervision.

People with diabetes who wish to try the 16:8 intermittent fasting plan should see a healthcare professional before making changes to their eating habits.

The 16:8 intermittent fasting plan is a time-restricted form of intermittent fasting. It involves an 8-hour window for food consumption and fasting for 16 hours.

Potential benefits may include weight loss, fat loss, and a reduction in the risk of some diseases. People doing 16:8 intermittent fasting should focus on eating high fiber whole foods and staying hydrated throughout the day.

The plan is not right for everyone. Individuals who wish to follow the 16:8 intermittent fasting diet should speak with a doctor or dietitian if they have any concerns or underlying health conditions.