Nutrition

Beginner’s Guide Intermittent Fasting

Intermittent fasting has been a popular trend for some years now. In contrast to most diets it does not focus on what you eat but much more on when you eat. With Intermittent Fasting you switch between fasting periods and eating on a regular schedule.

What does the science say about it?

Studies about intermittent fasting have shown that it can be effective to weight loss and people have less muscle loss compared to calorie restricted diets. A 2014 study showed that fasting may be beneficial for delaying the aging process and age-associated diseases such as Alzheimer’s, diabetes and hypertension. Most promising results were found in relation to prevention of obesity, diabetes and high blood pressure when fasting is done during the night hours.

How should I start Intermittent Fasting?

While there are many different methods the most popular one is the 12/12 Method: During this method you fast every day (or 4 days a week) for 12 hours and concentrate the food intake on the remaining 12 hours of the day. As an example, you stop eating at 7pm on one day until 7am on the next day.

Common rules are:

No food during fasting hours

Non-caloric drinks like unsweetened coffee, tea or water are allowed

Try to eat a balanced diet during the eating periods. However, there are no restrictions whatsoever.

Risks and Precautions

People that are not used to long fasting periods might feel some discomfort like hunger, headaches, constipation or dizziness. While most people react well to intermittent fasting it is always recommended to discuss this topic with you doctor and registered dietitian to avoid any harm. Intermittent fasting is contraindicated for persons who are underweight, have an eating disorder, are pregnant or breastfeeding.

Conclusion

Even though there are many promising studies, the effects on weight loss and intermittent fasting are still under investigation. Many studies were conducted on animals or were small or short-term. More research on the long-term effects on humans is needed.

Intermittent fasting can be a powerful tool to bring structure into your diet, but it is important to note that the best way for a healthy lifestyle is to improve the quality of your diet and exercise regularly.

Sources:

  1. Varady KA. Intermittent versus daily calorie restriction: which diet regimen is more effective for weight loss? Obes Rev. 2011;12(7):e593-601. doi:10.1111/j.1467-789X.2011.00873.x

2. Longo VD, Mattson MP. Fasting: Molecular Mechanisms and Clinical Applications. Cell Metab. 2014;19(2):181-192. doi:10.1016/j.cmet.2013.12.008

3. MPH MT MD. Intermittent fasting: Surprising update. Harvard Health Blog. Published June 29, 2018. Accessed October 1, 2020. https://www.health.harvard.edu/blog/intermittent-fasting-surprising-update-2018062914156

4. Sutton EF, Beyl R, Early KS, Cefalu WT, Ravussin E, Peterson CM. Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even without Weight Loss in Men with Prediabetes. Cell Metabolism. 2018;27(6):1212-1221.e3. doi:10.1016/j.cmet.2018.04.010

Written by:   Veronika Monteiro Kisslinger, Dietetic Intern, Hunter College

Reviewed by: Nazirber Maduro, RDN, CDN, CDCES

Nazirber Maduro, RDN, CDN, CDCES

Nazirber Maduro is a bilingual registered dietitian and nutritionist who believes that healthy and delicious food should be enjoyed at any stage in life. She helps people transform the way they eat and find joy in food through the practice of food and lifestyle medicine.

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