Intermittent fasting… what is it? Should you do it? If so, how should you do it?
Bet you have a few of those questions above. Well, never fear, as always I am about to weigh in with the help of all my experts and medical professionals from registered dieticians to endocrinologists so you get the answers you're after.
First, let’s discuss what fasting actually means and what it doesn’t. Contrary to some popular misconceptions, fasting does not mean reducing calories. Fasting simply refers to a period of time where you are not eating. Now, this can lead to calorie restriction if you don’t eat for long periods of time, but fasting and calorie restriction are NOT one in the same.
Calorie restriction is when we simply watch how much food we take in no matter what hours of the day we eat these calories.
Fasting on the other hand is about timing your calorie intake - no matter how little or how great that intake is. Technically speaking, if we looked at a 24 hour day and took a period of that day where you didn’t eat it would be considered a fast – no matter how many calories you took in. Inherently we do this already. It’s known as breakfast – breaking your overnight fast. This is the ideal way to incorporate intermittent fasting. You simply schedule your meals during the day over an 8 to 12 hour period. For example: Breakfast, then 3 to 4 hours later lunch, then 3 to 4 hours later snack, then 3 to 4 hours later dinner. Then you don’t eat again until your breakfast the next day.
Studies show us the minimum amount of time this should be done is 12 hours of fasting daily up to 16 hours of fasting daily for optimal benefits. The benefits are not actually weight loss related because arguably you would still be eating the same amount of calories, but simply confining those calories to a certain period of your day. So why do it? Because that period of the day where you are not eating frees your body up to do some much needed housekeeping.
Now, when done with calorie restriction you will definitely lose weight because that’s how our bodies burn stored fat. We take in less energy than we burn in a day and this leads to weight loss as fat is simply stored energy.
Together however, the housekeeping benefits are two-fold. In a nutshell, it kinda works like this: your body's nutrient sensing pathways team up to signal when there’s an abundance of nutrients (proteins and carbohydrates) available to work with. Once your cells notice that there’s plenty of glucose and amino acids to go around, they spend less time seeking out damaged cells to break down for their nutrients. Instead, they start using all those extra nutrients to grow cells.
By eating too much as well as too often, it causes the process of autophagy (the breaking down of damaged cells) to greatly slow or shut down. Your body figures, “Why get rid of damaged cells when I have plenty of nutrients and hormones floating around?” But the longer autophagy is shut down, the more damaged, misfolded protein cells start stacking up. This leads to “protein aggregation,” which can cause bad things to happen, including cell dysfunction and tissue damage that can eventually lead to disease. No bueno.
In summation, intermittent fasting helps us fight disease and slow down the aging process. Calorie restriction does the same, but also helps us lose weight by reducing our energy intake. If you don’t have weight to lose you can still get the immunity and anti-aging benefits from intermittent fasting without cutting calories, just be mindful not to overeat.
Where the whole thing can get wonky is when we starve our bodies on extreme diets like cleanses that dramatically reduce calories for days on end. This causes a host of issues on the opposite end of the spectrum. Because calories and nutrients are so few and far between your body cannibalizes healthy tissue, muscle, and bone because it thinks it’s starving. And, it also signals a biochemical slowing of your metabolism (also for perceived survival purposes), which leads to yo-yo weight gain or re-feeding syndrome. Which is a fancy way of saying that your body changes your biochemistry to slow your metabolism down so you are more efficient at saving energy. Not good when it comes to weight management.
Bottom line, don’t overeat (consume more calories than your body burns in a day). Don’t starve yourself with long extreme fasts, cleanses, or dramatic period of calorie reduction. Create at least 12 hours where you don’t eat between dinner tonight and breakfast tomorrow. This will help you stay lean, immune, and young inside and out!