We've all heard of different diets that claim to help you slim down, get more energy, or feel more hydrated. Whether that's eating or avoiding certain foods, tracking things like your intake and exercise, or doing things on a certain schedule, the thing most traditional diets have in common is calorie restriction. Today's topic is intermittent fasting! Let's talk about it all means and if this way of eating fits into diet culture or not.
First of all, what is it? Intermittent fasting involves cyclic intervals of fasting alternating with normal eating patterns allowed. Some restrict eating to an eight-hour window per day, leaving the remaining 16 hours as fasting hours; this time is often planned to be within the sleep schedule to make it easier. Others implement the “5:2 diet” which promises if you fast two days a week, you can eat anything you want during the remaining five days. Still others fast for religious reasons, and may or may not think about the caloric aspect of these possible weight loss strategies much, but more as a way to focus on their beliefs. There are more iterations of intermittent fasting, mostly pursued in the hopes of losing weight by ketosis.
Ketosis is a process in the human body that allows you to utilize energy stored in fat when you're in a fasted state (rather than a fed state). If you don’t eat for 10–16 hours, your body will go to its fat stores for energy, and fatty acids called ketones will be released into the bloodstream. During a fasting period, people often limit themselves to water and zero-calorie drinks, or nothing at all. Intermittent fasting is a way of eating based on time instead of calories. In other words, it doesn't restrict what you eat, but rather when you eat.
Fasting is safe when done for short periods of time, but does it work for weight loss? In short, it can but you have to be careful about it and it's rarely sustainable. Research suggests that consuming smaller meals is more effective for weight loss than restricting eating to a narrow time window. Often people will overeat on nonfasting days, due to the feast-or-famine, or scarcity, mindset that can occur. This can create a caloric surplus instead of a deficit, leading to weight gain. “Caloric restriction, undernutrition without malnutrition, is the only experimental approach consistently shown to prolong survival in animal models,” Freedland and colleagues stated in a study on the effects of intermittent fasting on prostate cancer growth in mice (Prostate Cancer Prostatic Dis 2010; 13:350–5). In the study, mice fasted twice a week for 24 hours, but were otherwise permitted to eat at liberty. During nonfasting days, the mice overate. Overall, the mice did not lose weight, counteracting whatever benefits they might have seen from the fasting. Intermittent fasting with compensatory overeating “did not improve mouse survival nor did it delay prostrate tumor growth” - to apply this to humans, fasting 2 out of 7 days per week doesn't work any better than just cutting down on your excesive calories seven days a week. If you're looking to drop down some weight, the goal should be to reduce the total amount of calories consumed rather than focusing on when those calories are consumed.
Comments