(Part of our January series on S3 Weight Management - Systematic, Stratified and Sustainable)
In the past year - one of the hottest health trends has been intermittent fasting and one it's most commonly used variants - time restricted eating.
A recent New England Journal of Medicine article highlights the physiology of fasting as well as the potential benefits. Two years ago on the Better Blog we wrote on "Why time restricted eating makes sense (and maybe you should try it) which provides much of the scientific evidence for the benefits of fasting.
What we want to emphasize here is something a bit different and even simpler:
Why is this important?
From a weight management perspective - the simplest answer is that you will eliminate the empty or extra calories of night time snacking...and that might be all that there is to it.
But I do think there is more; our bodies follow a diurnal rhythm that very closely follows a 24 hour light dark cycle.
During the light part of the cycle, many genes are activated, while others are turned off, preparing our system for what is expected during the day:
During the dark part of the cycle, genes that were activated in the day get turned off, and others get activated, again in the effort of setting our system up for the expected activities
Up to 40% of our genes are affected by the diurnal rhythm - many by light, but some by the presence of absence of food.
Putting this more simply, our bodies expect food in the daytime and fasting in the evening - evolution has designed us this way.
Other benefits from going 12 hours without food is that it will improve metabolic flexibility - that switch that allows the body to go from utilizing stored carbohydrates to burning fat. If we want to lose weight, we obviously need this flexibility.
In our thinking, we don't really think about going 12 hours a day without food as being a form of intermittent fasting - we think it is normal (and optimal) human behaviour.
It is most likely what most of our grandparents did and it is certainly what you see in traditional societies.
Consistently going 12 hours without food will likely provide many of the demonstrated benefits from intermittent fasting:
If you are interested in intermittent fasting, starting with 12 hours without food is the logical first step.
We recommend that before starting IF, you have these foundations in place:
After 4 to 6 weeks extending the fast is something you can explore.
The one major caveat to this is really important - if you are taking medications - please check with your doctor and come up with a plan before you start any time of fasting or time-restricted eating.
For other posts in this series:
On January 22nd - we will launch a new group program - fully covered by MSP (for those with a BMI >30 or a BMI between 27 and 30 and a weight related diagnosis).
During the month of January - we will be posting about the foundational behaviours for sustainable weight management - stay tuned.
If you would like to learn more about the S3 program and whether you are eligible please check out our Sustainable Weight Management program page.
Dr. Brendan Byrne