In intermittent fasting, what essentially takes place in the body is that one source of energy — which can facilitate the accumulation of body fat — is switched for another.
Our bodies run on glucose, or simple sugar, but when we fast for a longer period of time, that energy source becomes unavailable.
Our system needs to identify a different kind of “fuel.” That is when the body begins to convert certain types of body fat into fatty acids, which are easily absorbed by the blood.
Fatty acids, in turn, produce molecules called ketones, which the body uses as its new source of energy.
Stephen Anton, a researcher at the University of Florida College of Medicine in Gainesville, calls this process “flipping the metabolic switch.”
“This switch,” explains Anton, “can happen after a certain period of time fasting. It’s a gradation in which your metabolism over time shifts to use higher and higher amounts of ketones for energy.”
He and his team were interested to learn more about how this switch occurs, and whether it could bring other health benefits, alongside weight management.
For this purpose, they reviewed numerous recent studies focused on the mechanisms and benefits of intermittent fasting.
The team’s review, published in the journal Obesity, suggests that intermittent fasting may be more healthful than other dieting strategies, as ketones put less stress on cells than the byproducts of other dieting styles.
Significant weight loss regardless of style
Anton and his colleagues explain that the switch usually begins to take place after 8–12 hours of fasting, though in the case of individuals who practice intermittent fasting, the fasting strategies vary.
The researchers focused on the two most common types of intermittent fasting diets, the first of which is based on time restrictions for eating.
In it, the dieter may fast for a number of hours per day — for instance, 16 hours — while allowing themselves to eat anything they’d like over the remaining hours.