Is Intermittent Fasting Effective for Weightloss?

I get this question a lot as a dietitian and my answer is ‘Yes, it does! But not convenient or sustainable’.

Intermittent fasting means voluntarily abstaining from food and sugary drinks within some hours of the day followed by a normal eating routine. There are three main types of Intermittent fasting (excluding religious fasting):

  • Alternate-day fasting—it means you get to eat on alternate days. Example: Mon-Wed-Fri or Tue-Thur-Sat while you stick to your normal eating routine on non-fasting days. The goal is that you take only 25% of your calorie needs during fasting days.
  • Time-restricted feeding—involves fasting for 8-12hours of the day (sleeping time inclusive) and eating during the remaining time frame. For example, you can choose to eat between 8 am-4 pm and fast from 4 pm till the next day.
  • 5:2 diet or Modified Fasting:  On this regimen, you get to fast  2 days per week while taking25% of daily calorie needs, followed by 5days of normal eating routine.

How effective is Intermittent fasting?

A  review of 40 studies found that intermittent fasting was effective for weight loss, with a typical loss of 7-11 pounds (3-5kg) over 10 weeks. Quite a several studies did not record a significant difference in weight loss between the intermittent fasting group and the moderate calorie restriction group.

Side effects of intermittent fasting usually include serious hunger pangs, decreased concentration especially at work, tiredness, lightheadedness, and nausea on fasting days. All these usually result in a high rate of dropout, making the program only effective in the short term. Also, some people might eat more than usual on non-fasting days or periods resulting in no weight loss.

You should not go on intermittent fasting if you :

  • Have Diabetes
  • On routine medication
  • Pregnant or breastfeeding
  • Are an adolescent

Dietitians rarely recommend Intermittent fasting as a treatment for weight loss due to the side effects and low compliance rate. We emphasize healthful eating instead of fasting on and off, however, should you decide to go on the program, your dietitian can ensure you get adequate nutrients or even place you on certain nutrient supplements during the fasting periods. But, why go on a diet program with side effects when you can achieve the same result on a moderate calorie restriction diet? If you are struggling with weight loss, click on the ‘consult the dietitian’ to begin a personalized diet program that best suits you!


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