Is it bad to do 18 hours of intermittent fasting every day?
For some people, eating all their daily calories within a 6-hour window is ideal. These are people who, for whatever reason, have the genetic make-up or a circumstantial issue that limits the time in which they can digest enough food. For the rest of us, 18 hours of intermittent fasting should be ‘intermittent’ – occurring at irregular intervals, not at a continuous or steady rate.
Let’s compare a person using intermittent fasting with a person using exercise to achieve the desired outcome of improving metabolic health.
As we know, the body of the intermittent faster becomes more efficient with a shorter window in which to eat. Likewise, the body of the exerciser becomes more efficient with whatever stress from cardio, strength training, or flexibility that is being incurred.
During the time in which the adaptations are happening, both people are witnessing results and seeing successful outcomes. However, a time will come when their bodies fully adapt to the new routines. To experience additional results, the person fasting will need to further reduce the window of eating time while the person exercising will have to increase their speed or distance, weights, or range of motion. Furthermore, that once ‘new’ strategy to improve metabolic health must become a sustained part of daily living to maintain the results already achieved.
The bottom line is this: The slower the body can adapt to the changes being made, the greater the window you have for not only achieving but sustaining your goal of metabolic health.
Intermittent fasting keeps the body’s hormones reactive to changing blood sugars while preventing the body from adapting to a set schedule. Non-consecutive days of 18 hour fasting each week lengthens the time the body can be ‘trained’ to improve function, burn body fat and embrace the new strategy as a sustainable lifestyle change. It also keeps you sensitive to your body’s eating cues, like hunger and fullness, that get overriden when intermittent fasting. The last thing we want to do is begin ignoring our bodies thinking that we know exactly what it needs without it ever having a chance to speak up.