The Effect of Intermittent Fasting on Metabolism


Many of us wonder whether intermittent fasting can enhance our metabolism, helping us easily lose weight. So, let’s know what nutritionists have to say about this.

We have been getting the advice not to eat less than 1200 calories. If we eat lesser calories, our metabolism will be slowed down. However, intermittent fasting (IF), wherein the levels of calories is brought down to 500 calories, is recently gaining popularity. This is because, latest research has a different story to tell. It says that IF can actually boost metabolism. But before elaborating on that, let us first understand what intermittent fasting is.

What is Intermittent Fasting?

Intermittent fasting involves periods of fast and periods of regular consumption of food. Fasting means very little to no consumption of food. It has been practiced for so many years. New type of fasting, called intermittent fasting is getting popular in the dieting sphere; all thanks to books like “The 8-Hour Diet and The Fast Diet.”

Types of Intermittent Fasting

The most common types of IF are 5:2 and 16:8 approach:

  • 5:2 Fasting Approach: Two nonsequential days in which only 25% of daily requirements of calories is consumed, which makes it for 500 calories for women and 600 for men. The other 5 days, you eat your normal food with normal calories. Some people practice 4:3 approach in which fasting is done on alternate days. After a day of fasting, you have a day, in which, you can have your regular food.
  • 16:8 Fasting Approach: All the food is consumed in the 8- to 10-hour window, but you don’ t eat anything in the 14-16 hours of the day. Generally, people miss out on breakfast and settle on an 8-hour window from 11 AM to 7PM.

Can Intermittent Fasting Help You Lose Weight?

A major motivation for many people to try out IF is its weight loss-specific benefits. It has been reported that 3-8% body weight can be lost in 1 to 6 months. Researchers are striving to establish if IF can be considered as a long-term method for dieting.

IF has other benefits too in comparison to conventional fasting. Intermittent Fasting:

  • causes more loss of fat around the abdominal area
  • causes little loss of lean body mass
  • improves the level of good cholesterol and fasting insulin
  • decreases markers of inflammation

Research says that IF has the same or lesser bad effects on metabolism when compared with conventional dieting. The reason that is cited for it to improve metabolism is less loss of lean body mass and more burning of body fat.

Weight loss cannot happen without the loss of lean body mass. Research suggests that lower percentage of lean body mass is lost when trying to attain weight loss with IF in comparison to the conventional weight loss method, wherein the percentage of lean body mass is relatively low.

Preserving lean body mass implies that the calorie-burning process of the body will not slow down much. And in times of fasting, the body taps into fat stores and burns greater fat mass to convert it into energy.

What Promotes The Success of IF

There are two major steps or keys for the success of Intermittent Fasting: Fasting periods and periods of normal calorie intake:

  • Calorie intake is practically zero for short periods. If you continue to fast beyond the period and do not start with the normal calorie intake then the metabolism will slow down. 5:2 and 16:8 helps in burning calories. This alternating periods of fasting and normal food intake do not make the metabolism slow.
  • You should, however, not eat excessively during the periods of normal food intake. Normal intake means meeting the calorie needs with healthy foods. It does not give you liberty of binging on excessive foods and the ones that are your favorite instead of being healthy.

How Fasting Affects Your Metabolism

If little is good, then a lot may not be better! You may feel motivated to continue with fasting after a day, but the body needs normal calories to keep the metabolism going on and continue the process of fat burning. If your intake of calories is very low after a day of fasting, then the body will go into the starvation phase and the metabolism will eventually slow down.


IF is safe and quite an effective way to improve health and lose weight. But, not everyone can do it. Long-term weight loss is only possible with normal and healthy intake of food. So, choose an eating regimen that works best for you!