Fasting may provide several health benefits, including weight loss, blood sugar management, and protection against medical conditions like cancer and heart disease.

Despite its recent surge in popularity, fasting is a practice that dates back centuries and plays a central role in many cultures and religions.

Fasting is defined as abstinence from all or some foods or drinks for a set period. There are many different ways of fasting. Generally, most fasts are performed over 24–72 hours.

Intermittent fasting, on the other hand, involves cycling between periods of eating and fasting, ranging from a few hours to a few days at a time. Fasting can have health benefits, such as increased weight loss and better brain function.

Here are 6 health benefits of fasting — backed by science.

Several studies have found that fasting may improve blood sugar management, which may be helpful for those at risk of developing diabetes.

A 2023 study of 209 people found intermittent fasting 3 days per week can reduce the risk of type 2 diabetes by increasing insulin sensitivity.

Decreasing insulin resistance can increase your body’s sensitivity to insulin, allowing it to transport glucose from your bloodstream to your cells more efficiently.

Coupled with the potential blood sugar-lowering effects of fasting, this could help keep your blood sugar steady, preventing spikes and crashes in your blood sugar levels.

A 2022 review of research notes that intermittent fasting, including time-restricted feeding may reduce risk factors associated with metabolic syndrome, a group of five risk factors that increase the likelihood of type 2 diabetes, heart disease, and stroke. However, additional studies are still needed to compare the effects of fasting with restricting calories.

While acute inflammation is a natural immune process used to help fight off infections, chronic inflammation can seriously affect your health.

Research shows that inflammation may be involved in the development of chronic conditions, such as heart disease, cancer, and rheumatoid arthritis. Some studies have found that fasting can help decrease levels of inflammation and promote better health.

One 2022 review of 18 studies found that intermittent fasting could significantly reduce levels of C-reactive protein, which is a marker of inflammation.

Heart disease is considered the leading cause of death worldwide, accounting for an estimated 19 million deaths globally in 2020. Switching up your diet and lifestyle is one of the most effective ways to reduce your risk of heart disease.

Some research has found that incorporating fasting into your routine may be especially beneficial for heart health.

One review revealed that alternate-day fasting could reduce levels of total cholesterol and several risk factors for heart disease in people with overweight compared to a control group.

Many dieters experiment with fasting to try to lose weight. Theoretically, abstaining from all or certain foods and beverages should decrease your overall calorie intake, potentially leading to increased weight loss over time.

A 2022 review found that intermittent fasting was more effective in inducing weight loss compared to continuous calorie restriction.

In addition, other research has found that fasting may lead to greater reductions in body fat and belly fat compared to continuous calorie restriction.

A 2021 review published in the American Cancer Society Journal notes that intermittent fasting may benefit the treatment and prevention of cancer in some situations. It may decrease tumor growth and toxicity from chemotherapy in some people.

But they note that more high quality clinical trials are needed and recommend that people undergoing cancer treatment only do intermittent fasting as part of a clinical trial. For some situations and types of cancer, it could potentially have a negative effect.

Despite these promising findings, additional studies are needed to look at how fasting may influence cancer development and treatment.

How to start fasting

There are many different types of fasts, making it easy to find a method that fits your lifestyle.

Here are a few of the most common types of fasting:

  • Water fasting: This involves drinking only water for a set amount of time.
  • Juice fasting: This entails only drinking vegetable or fruit juice for a certain period.
  • Intermittent fasting: Intake is partially or completely restricted for a few hours up to a few days at a time, and a regular diet is resumed on other days.
  • Partial fasting: Certain foods or drinks, such as processed foods, animal products, or caffeine, are eliminated from the diet for a set period.
  • Calorie restriction: Calories are restricted for a few days every week.

Within these categories are also more specific types of fasts.

For example, intermittent fasting can be broken down into subcategories, such as alternate-day fasting, which involves eating every other day, or time-restricted feeding, which entails limiting intake to just a few hours each day.

Safety and side effects

Fasting may not be suitable for everyone and may cause side effects. For example, if you have diabetes, fasting can lead to low blood sugar levels, which could be dangerous.

It’s best to talk with a doctor first if you have any underlying health conditions or are planning to fast for more than 24 hours.

Additionally, fasting is not generally recommended without medical supervision for older adults, adolescents, people with underweight, or people undergoing cancer treatment.

If you decide to try fasting, be sure to stay well-hydrated and fill your diet with nutrient-dense foods during your eating periods to maximize the potential health benefits.

Additionally, if fasting for longer periods, try to minimize intense physical activity and get plenty of rest.

The bottom line

Fasting may have potential health benefits, including weight loss, improved blood sugar management, heart health, and cancer prevention.

When coupled with a nutritious diet and healthy lifestyle, incorporating fasting into your routine could benefit your health.