Intermittent fasting

Published: 25/04/2022
Katarzyna Kieszkowska
She holistically guides clients and creates educational programs. She continues to expand her knowledge of nutritional medicine, food therapy, natural approaches to health and lifestyle. She is passionate about a healthy lifestyle.

Date of the last update: 25.04.2022

Intermittent fasting is a diet plan based on simple principles. This regime has no specific guidelines as to the type and quantity of food you can eat, but is an effective way to lose weight and improve memory and concentration.

The main idea behind intermittent fasting is the time when you can eat – it is limited to the so-called eating window, which is restricted to some hours or days.

Table of Contents:

  1. Intermittent fasting –  guidelines
  2. Intermittent fasting – effects on the body
  3. IF diet – effects on your brain
  4. What to eat
  5. IF diet – contraindications

You can read this article in 3 minutes.

Intermittent fasting guidelines

The IF diet, or Intermittent fasting is a nutritional strategy based on the so-called periodic fasting. This means that during the day, we eat for a certain period of time, followed by a longer break, which is the so-called “fasting window”. The most commonly used model is 16/8, that is we eat for eight hours and abstain from eating for the next 16 hours. For example, we eat dinner at 6 pm and the first meal the next day at 10 am. During the fasting period, we can drink tea or coffee.

Beginners are recommended to start fasting from a 12-hour break to get used to the new eating pattern. Then you can move to the 14/10 model and so on up to 16/8.

Sometimes the food intake period is shortened even to 4–6 hours, which lengthens the fasting window to 18–20 hours, and these the 18/6 and 20/4 protocols.

Another variation of this eating model is the 5/2 diet, where you fast for two days during the week.

Intermittent fasting – effects on the body

Intermittent fasting can result in weight loss because we limit evening snacking. With this model, we reduce our overall calorie intake. Many people wonder what to eat on the IF diet. There is no specific menu, but it is important to eat healthy meals and avoid high-calorie fast food. It is recommended to eat several small meals and snacks throughout the day to prevent fluctuations in blood sugar levels and keep hunger pangs under control. The study conducted by researchers at the University of Illinois at Chicago confirmed that intermittent fasting effectively aids to achieve weight loss in people with obesity. This eating pattern has a positive effect on metabolism. The fasting period helps to burn fat and convert it into the energy needed to fuel us during the day. In addition, cyclical, short-term fasting is beneficial to health.

There are numerous positive reviews concerning intermittent fasting and lots of information about the effects of this diet model available on internet forums.

IF diet – effects on your brain

Intermittent fasting positively affects both your body and mind. This eating pattern enhances the ability to concentrate. Scientific studies report that fasting has a positive effect on increasing the level of neurotransmitters associated with concentration. Brain neuroplasticity is also enhanced as your body goes into ketosis. In addition, intermittent fasting can prevent the development of depression and inflammation. With fasting windows, you can learn to distinguish between hunger and satiety, which prevents emotional hunger pangs and eating when you feel bored. Avoiding spikes in insulin levels allows to prevent fatigue.

Check out also: Types of hunger – how to distinguish them

What to eat

The diet for people following the eating window pattern needs to be carefully balanced. The diet should include: 

  • fish,
  • healthy, preferably organic meat,
  • wholegrains,
  • nuts and seeds,
  • cold-pressed vegetable oils, e.g. linseed oil, olive oil,
  • fruit and vegetables,
  • eggs,
  • dairy products, preferably fermented (if there are no contraindications).

IF diet – contraindications

Healthy people who properly follow intermittent fasting guidelines should not experience any side effects. This restricted eating strategy is safe for health. However, fasting for too long may lead to nutrient deficiencies. People who regularly take medications should consult their doctor before they decide to follow the IF diet.

Contraindications for fasting include:

  • Children,
  • pregnant women,
  • people who are underweight and have eating disorders,
  • people with a history of cardiovascular disease,
  • people with diabetes or hypoglycemia.

It is worth adding that intermittent fasting is not another miracle diet. This eating plan can be used whenever you want to support your body not only to fight obesity, but also to improve your well-being.


Leucine, glucose, and energy metabolism after 3 days of fasting in healthy human subjects – PubMed (

Health effects of intermittent fasting: hormesis or harm? A systematic review – PubMed (

Varady i Hellerstein Alternate-day fasting and chronic disease prevention: a review of human and animal trials. Am J Clin Nutr. (2007). 86: 7-13.

Harris L, McGarty A, Hutchison L, Ells L, Hankey C. Short-term intermittent energy restriction interventions for weight management: a systematic review and meta-analysis. Obes Rev . 2018;19(1):1-13.

Headland M, Clifton PM, Carter S, Keogh JB. Weight-loss outcomes: A systematic review and meta-analysis of intermittent energy restriction trials lasting a minimum of 6 months. Nutrients. 2016;8(6).

Katarzyna Kieszkowska
She holistically guides clients and creates educational programs. She continues to expand her knowledge of nutritional medicine, food therapy, natural approaches to health and lifestyle. She is passionate about a healthy lifestyle.