Should you try intermittent fasting?

For many who would like to lose weight, the intermittent fasting (IF) method sounds appealing. On the non-fasting days, you can eat a normal, healthy meal with no restrictions on calories, and on the fasting days, the limited food you are allowed to eat is simple and quick to prepare.

What is a fast and how does an intermittent fasting diet work?

A fast: A time period during which someone goes without eating. There are several diets using intermittent fasting:

Alternate day fasting:  Someone using this diet alternates days of fasting, where only one meal is consumed that provides about 25% of the normal daily calorie allowance, with days of no restrictions (a healthy variety of food is encouraged).

5:2 diet approach (or other whole day fasting approach):  These diets allow eating a normal diet on five days of the week while two days of the week consists of complete fasting or eating a diet of no more than 400 – 500 calories. The two fasting days can be any days of the week, as long as they have a non-fasting day in between them.

Early Time  Restricted Feeding (eTRF): This method involving fasting on a daily schedule, with there being an 8-hour time window in the morning & afternoon for eating, say from 8am-3 pm.

The supporters of intermittent fasting programs theorize that when you fast, your body starts relying on burning stored fat to get the energy it needs and you will start to lose weight, as long as you do not eat too much unhealthy food on the non-fasting days. By eating normal meals on non-fasting days, someone using intermittent fasting will not have the slowdown in metabolism that someone who is on a long term low-calorie diet. Proponents of IF assert that the method may enhance your metabolism.

Does research show Intermittent Fasting to be effective? 

Studies of intermittent fasting diets show that they are just as effective for weight loss as diets that restrict calories. There is evidence that eTRF may also help reduce insulin resistance, however more studies on the relationship between IF and improvements in insulin resistance are needed. The long-term effects of intermittent fasting needs to be studied to determine if there are any negative impacts.

Who should try it?

Intermittent fasting diets are not for everyone. They are not for anyone under 18, for pregnant women, or anyone who could experience a health risk from fasting, so check with your doctor. Also, if you are someone who is used to eating every 3 hours, you may find this diet difficult. IF diets may affect fertility in women, so seek your doctor’s advice before starting an IF diet if you are trying to conceive.

Resources: 

https://www.hsph.harvard.edu/nutritionsource/healthy-weight/diet-reviews/intermittent-fasting/

https://www.ncbi.nlm.nih.gov/pubmed/29754952