Updated: Aug 5, 2022
Intermittent fasting (IF) is currently one of the most trending dietary practices for weight loss as well as improving health and lifestyles.
What is Intermittent Fasting?
Rather than focusing on what you eat, intermittent fasting is a diet practice that cycles between periods of feeding and fasting. A few common approaches to IF include:
Why is it so popular ?
One of the main reasons people practice IF is to manage their body weight. IF has been proven to aid in promoting weight loss in animal studies as well as human clinical trials. Research shows that two types of IF, particularly time-restricted feeding (TRF) and alternate day fasting (ADF) significantly reduced weight in overweight and obese patients after 8-12 weeks of intervention.
Just like any other fad diets, fasting can create calorie deficit which makes you lose weight. Besides that, fasting for an extended period of time can cause your glucose storage to be depleted, so your body starts to burn fat for energy. You might even feel less hungry once you have adapted to fasting.
According to researchers, IF may be a better alternative weight loss strategy compared to continuous energy restriction (CER). Although both dietary practices showed comparable effect in weight loss, IF seems to be easier to comply with as it doesn't require you to restrict calorie intake every single day. More importantly, IF reduces fat mass whilst having little to no impact on muscle mass.
Other health benefits
Apart from weight loss, IF may also benefit people who are at risk of developing diabetes as it is shown to improve blood sugar and insulin sensitivity in previous studies. It appears that the weight loss during IF is an important factor in determining improvements in insulin sensitivity.
During fasting, the body also induces important cellular repair processes, such as eliminating waste materials. In doing so, new cellular structures can be built which help to reduce inflammation and extend the lifespan of the cell. This is why IF is also known for slowing down the process of aging.
IF has the potential to be a powerful weight loss tool if it is done appropriately. However, further investigations are still needed to confirm the effectiveness of IF in the long run as most studies conducted were small-scaled and only lasted up to 12 months.
Be sure to consult a well-trained healthcare professional before making any dietary decisions. Always bear in mind that what’s right for someone else may not be right for you.
a) Is there any food that is allowed during fasting period?
You can still consume water, black coffee, green tea and other unsweetened beverages during intermittent fasting (as long as it doesn't contain any calories).
b) Is it really effective for weight loss?
Although intermittent fasting has shown some promising findings on weight loss, however, the subjects involved are small sample and mainly focused on specific population such as those who are overweight and obese. Therefore, more large-scale studies need to be done to confirm the long-term benefits of IF.
c) Is it safe for everyone?
Intermittent fasting may not be safe for certain people such as:
Pregnant or breast-feeding women
Children and teens under the age of 18
People with a history of eating disorders
People with diabetes or blood sugar problems
People with digestive issues (gastritis, gastric ulcers, GERD)
People who are underweight
d) Does it have any downsides?
Some potential side effects during fasting are irritability, headaches, hunger, fatigue, low energy and poor work performance.
e) Does that mean I can eat whatever I want during the eating window and still lose weight?
Although intermittent fasting did not specify which type of foods to eat, it does not imply that you can lose weight while overly indulging in high-calorie unhealthy foods (e.g. hamburgers, fries, pizza & sugary drinks). Keep in mind that diet quality is still the key to maintaining health.
Barnosky, A. R., Hoddy, K. K., Unterman, T. G., & Varady, K. A. (2014). Intermittent fasting vs daily calorie restriction for type 2 diabetes prevention: a review of human findings. Translational Research, 164(4), 302-311.
Lowe, D. A., Wu, N., Rohdin-Bibby, L., Moore, A. H., Kelly, N., Liu, Y. E., ... & Weiss, E. J. (2020). Effects of time-restricted eating on weight loss and other metabolic parameters in women and men with overweight and obesity: the TREAT randomized clinical trial. JAMA internal medicine, 180(11), 1491-1499.
Stockman, M. C., Thomas, D., Burke, J., & Apovian, C. M. (2018). Intermittent fasting: is the wait worth the weight?. Current obesity reports, 7(2), 172-185.
Varady, K. A., Cienfuegos, S., Ezpeleta, M., & Gabel, K. (2022). Clinical application of intermittent fasting for weight loss: progress and future directions. Nature Reviews Endocrinology, 18(5), 309-321.
Zang, B. Y., He, L. X., & Xue, L. (2022). Intermittent Fasting: Potential Bridge of Obesity and Diabetes to Health?. Nutrients, 14(5), 981.