Intermittent Fasting: Facts vs. Myths

Intermittent fastIng is a term used to describe a variety of eating habits that feature alternating periods of fasting — abstinence from food — and eating.

The fasting period can last from 12 hours a day to several consecutive days, with a consistent repeating pattern over the course of a week.

The most important types of intermittent fasting are:

  • modified fasting or the 5:2 diet — This protocol involves fasting 2 non-consecutive days per week and eating normally for 5 days
  • Fasting on the second day — Fasting days are alternated with days when food and drink are consumed normally and without restrictions
  • time limited meal — a type of intermittent fasting that limits the “eating window” to 4–12 hours, which initiates a 12–20 hour daily fast. Individuals eat to satiety during their eating windows with no calorie restrictions.

Of these, time limited meal is the most popular and possibly what most people are referring to when mentioning intermittent fasting.

The 16:8 pattern — eating during an 8-hour window and fasting for 16 hours a day — might be the most recommended time-limited eating pattern.

Much of the research on intermittent fasting and time-restricted eating considers the effects of fasting on the body’s natural circadian rhythm.

That circadian rhythmalso called the circadian clock, represents the 24-hour cycle of metabolism in the body, including the control of the sleep-wake cycle, blood pressure, mood regulation, and hormone balance, to name a few.

It is influenced by light and darkness over the course of the day, eating habits and the timing of meals.

A growing number of research suggests that eating for longer periods of the day, from 12 to 15 hours, can disrupt circadian rhythms and increase the risk of chronic diseases such as heart disease, cancer and type 2 diabetes.

Therefore, a primary goal of fasting, particularly time-restricted eating, is to reduce the time spent eating during the day by extending the overnight fast.

The study of the relationship between circadian rhythms and food timing is called chrono nutrition.

Many of the benefits of intermittent fasting are attributed to daily fasts of no less than 12 hours, although some research suggests that at least 16 hours of fasting may be required.

Generally during 12-36 Hours of uninterrupted fasting, the liver glycogen the stores are exhausted, general metabolic processes are changed and positive health effects are observed.

Here are some of the scientifically proven benefits of intermittent fasting.

1. Improved cholesterol levels

Knowledge of animals and humans research show favorable changes in cholesterol levels.

Intermittent fasting has that potential to lower total cholesterol, triglycerides, LDL cholesterol or “bad” cholesterol and to increase HDL cholesterol or “good” cholesterol.

Elevated total cholesterol, LDL cholesterol and triglyceride levels are risk factors for heart disease.

2. Blood sugar control

Intermittent fasting may improve blood sugar control by reducing insulin resistance and increasing insulin sensitivity.

That leads to lower Fasting blood glucose and glycated hemoglobin – HbA1c – values.

As a matter of fact, experimental research in adult males with type 2 diabetes demonstrated the potential for intermittent fasting as a therapeutic approach that may reduce the need for insulin therapy.

3. Changes in body composition

changes in body weight etc composition are among the best-studied effects of intermittent fasting.

Several studies have shown that intermittent fasting can result in weight loss of between 3-7% of body weight in an average of 8 weeks. The research also found that this method could lead to fat loss.

fasting in a 14:10 pattern – a 10-hour eating window and a 14-hour daily fast – may address risk factors for metabolic syndrome, including by reducing waist circumference, body fat percentage, and visceral fat.

Intermittent fasting can thus alleviate metabolic syndrome, a number of risk factors that increase the risk of heart disease and type 2 diabetes.


A Review 2015 of 2,650 adult women reported that reducing calorie intake in the evening and fasting longer at night may reduce inflammation and the risk of breast cancer and other inflammatory diseases.

observational research of 26,092 adult males over a 16-year period suggested that r.

Other areas of health in which intermittent fasting is being researched include, among others longevity and neurodegenerative diseases such as Parkinson’s disease.

Despite the many touted benefits of intermittent fasting, there are some downsides as well.

side effects

Intermittent fasting may be safe for heart and metabolic health, but according to a Review 2017it can cause negative side effects in some people, such as:

  • increased feeling of hunger
  • increased irritability
  • deteriorated mood
  • increased thoughts about food
  • fatigue
  • Fear of feeling out of control when eating
  • overeating during the eating windows
  • difficulty concentrating.

proof quality

Additionally, most of the research on intermittent fasting is based on animal studies little Long-term human research available.

Also a Review 2021 found that only six out of 104 purported health benefits of intermittent fasting were supported by moderate-to-high quality evidence and most of the findings were based on low-quality research.

This means that more thorough human research into the long-term health benefits of intermittent fasting is warranted.

Intermittent fasting isn’t the only diet that results in the above benefits.

calorie restriction

calorie restriction with a reduction in daily energy requirements of about 25% without changing meal times had a positive effect on promoting general health.

Some research suggests that the health effects of intermittent fasting are no greater than those observed with calorie-restricted diets.

In fact, results are for weight and/or fat loss, body fat percentage, and metabolic risk factors comparable between the two.

However, research on intermittent fasting shows greater adherence over longer periods compared to calorie restriction and suggests it may be a more sustainable approach.

Mediterranean cuisine

That Mediterranean cuisine is a well-known diet pattern based on the traditional eating habits of the Mediterranean basin.

Like the potential heart friendly Benefits of intermittent fasting Research shows that long-term adherence to the Mediterranean diet reduces the incidence of heart attack and stroke by up to 30% after about 5 years.

Additional research on the Mediterranean diet demonstrates its protective nature against the development of colon cancer and the loss of nerve cells in Parkinson’s disease.

A major advantage of the Mediterranean diet compared to intermittent fasting is that similar results can be achieved without fasting.

Intermittent fasting describes a variety of eating patterns that alternate periods of fasting and eating with a consistent, recurring pattern over the course of a week.

Time-restricted eating is the most popular form of intermittent fasting and uses the principles of chrono-eating to extend overnight fasts and potentially reduce the risk of chronic disease.

Intermittent fasting may improve cholesterol, blood sugar control, weight and/or fat loss, lower inflammation, promote longevity, and support neurodegenerative diseases like Parkinson’s disease.

However, most of the research on intermittent fasting is based on animal studies, and human research is sparse and often of low quality.

Alternative non-fasting diets that produce results similar to intermittent fasting include calorie restriction and the Mediterranean diet.

Comments are closed.