Fasting Diets and Your Health: Is it Safe?

18 September 2019

Although fasting has been around for thousands of years in various religions and cultures, fasting is now becoming a popular way to lose weight, delay the aging process, and ward off disease. In the past doctors warned against fasting for weight loss, as it can be dangerous and have negative results. However, the new approach to the fasting diet has resulted in six different types of fasting diets for different goals and lifestyles. This new fasting method, called intermittent fasting, can be a healthy way to improve your health and well-being.

The benefits of fasting


Fasting is defined as a period of time without ingesting all or some food or drinks usually over a 24-72 hour time period. Fasting promotes autophagy, the body’s natural process of clearing debris and toxins from the body. Fasting, when approached the right way, can have many benefits for your health, which are now backed by scientific studies.


  • Weight loss: Short-term fasting has been found to increase weight loss and increase metabolism by boosting norepinephrine in the brain, without losing muscle tissue.
  • Blood sugar control: Fasting reduces insulin resistance, which helps regulate blood sugar.
  • Inflammation: Intermittent fasting helps reduce inflammatory markers in the blood by suppressing pro-inflammatory molecules called cytokines. This reduction in inflammation also helps protect the brain and promote the generation of nerve cells to help improve cognitive function.
  • Cardiovascular health: Fasting decreases the risk of heart disease by lowering cholesterol, triglycerides, and blood pressure due to consuming fewer calories and fat.
  • Metabolism: Fasting improves metabolic health by increasing the production of human growth hormone, which is responsible for growth, muscle strength, metabolism, and weight loss.
  • Cancer: Animal and test-tube studies show that exposing cancer cells to fasting was as effective as chemotherapy and helped decrease tumor formation.

Types of fasting diets

When choosing a fasting diet that is right for you, take into consideration your health goals, your lifestyle, and any preexisting conditions. Also, speak with your doctor or a registered nutritionist to help guide you during the process.


  1. 5:2 fasting: This type of fasting diet is the most popular intermittent fasting method and involves eating normally for five days out of the week while eating 500-600 calories on two days. Having shorter bouts of fasting is easier to adjust to than longer periods of fasting so it is easier to stick with it.
  2. Time-restricted fasting: This plan involves a 14-16 hour fasting period with a shorter “window” of time planned for eating. For instance, if one has their eating window from 9 am to 5 pm, the body will be able to fast for at least 14 hours before the next meal.
  3. Overnight fasting: This involves a 12-hour fasting period overnight, and the simplest fasting diet to follow. There are no long hours of starvation, but this method does not provide the full benefits of other fasting diets.
  4. Whole-day fasting: Fasting diets using this method involve a 24-hour fasting period. While this approach does result in weight loss, it is challenging to get all the required nutrients you need in just one meal.
  5. Alternate-day fasting: This includes fasting every other day, consuming 500 calories on fast days and eating normally the rest of the time. This method is a popular approach to weight loss, as it dramatically reduces calories and side effects.
  6. Choose-your-day fasting: This is a loose approach to fasting which allows you to choose your fasting schedule. You might choose to fast every other day or twice a week, for 16 hours at a time or 24 hours. However, this approach only has mild health benefits.


It is important to choose a fasting diet that works with your lifestyle and health goals. You should not fast if you are pregnant, trying to become pregnant, take diabetes medication, or you are on multiple medications. Also, you should not fast if you have a history of eating disorders, as fasting may lead to a relapse of unhealthy behaviors. Always speak with your doctor about dietary changes, especially if you have preexisting health issues.