Fasting has become a phenomenon within the past few years. Intermittent fasting was Google’s most researched diet lately, and its popularity continues to grow.
One common way to practice intermittent fasting is through time-restricted eating, which limits the amount of time in a day you can eat. There’s now a newer type of time-restricted eating that’s catching on: dirty fasting.
What is dirty fasting?
To understand dirty fasting, you first must understand time-restricted eating. Time-restricted eating requires limiting the hours you eat within a day to a 12-, 10-, or even eight-hour window. The last option, referred to as the 16:8 intermittent fasting diet, involves a 16-hour fast followed by an eight-hour eating window. For example, a 16:8 protocol can involve fasting between 8 p.m. and noon and eating between noon and 8 p.m.
Traditionally, only beverages with zero or very minimal calories—like water, black coffee or tea, and unsweetened herbal tea—are consumed during fasting hours, which has become known as “clean fasting.”
Research shows that time-restricted eating, or what’s thought of as clean fasting, may offer benefits that include cardiovascular protection, reductions in blood pressure and blood sugar, and weight loss.
Nonetheless, a new approach has emerged in which more calories, or certain foods, are allowed during the fasting window. The goal is to disrupt the concept of fasting as little as possible while achieving similar benefits as a clean fast. The practice is referred to as “dirty fasting.”
There is no human clinical research on the health benefits of dirty fasting, but some people who do it claim that the approach does provide similar benefits as clean fasting.
How does dirty fasting work?
Fasting has understood as the absence of calories. However, there is an emerging concept that redefines what it means to achieve a state of physiologic or molecular fasting. Basically, when your cells aren’t impacted in the same way they likely are during a “fed” state, it may allow for dirty fasting to still be considered a form of “fasting.”
In short, when you’re fasting, your calorie and carbohydrate availability is low, which causes your insulin levels to drop. As a result, the hormones glucagon and epinephrine, which trigger the release of stored fat from fat cells, rise. Some of that fat travels to the liver, where it gets converted to ketones and is released back into the bloodstream. These ketones become an energy source for the brain, in place of glucose, its typical fuel.
Some would argue that if glucose and insulin remain low and ketone levels remain elevated, physiological or molecular fasting is maintained. And this fasting state can potentially be achieved even with the limited intake of calories that a dirty fast allows.
In spite of that, there’s a whole lot we don’t know about dirty fasting, and there is very limited research to support some of the theories espoused online about health or weight loss outcomes associated with dirty fasting. In short, much more research is needed to understand the best way to practice dirty fasting and its possible benefits.