Dirty fasting - A newer approach to intermittent fasting

 

One common way to practice intermittent fasting is through time-restricted eating, which limits the amount of time in a day you can eat. For example, a 16:8 protocol involves 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, known as "clean fasting." Research shows that this may offer benefits that include cardiovascular protection, reductions in blood pressure and blood sugar, and weight loss. 

But 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. This practice is referred to as "dirty fasting."  But there are no definite answers to the types of food or drink that are allowed during the fasting window. Some say that any food or beverage during the fasting hours is fine, as long as it is less than 100 calories. Other only sanctions high-fat foods. And some allow artificial sweeteners because they are zero calories.

In a nutshell, during fasting, your glucose and insulin levels become low while ketone (i.e. the converted stored fat after going to the liver) levels remain elevated. But in fact, this fasting state can potentially be achieved even with the limited intake of calories that a dirty fast allows.

One 2021 study in the journal Nutrients points out that a lower protein intake has been shown to be more effective at not triggering metabolic pathways in the body that sense the availability of nutrients. 

Many people who are interested in dirty fasting seek the health benefits of time-restricted eating with the flexibility to be able to eat or drink something with calories during the fasting window. Proponents of dirty fasting say that flexibility helps them stay on track with their fasting routine because they are not as limited or as hungry. And there can also be psychological or behavioral benefits to it. Time-restricted eating helps them prevent overeating, maintain a consistent eating schedule, and eat more mindfully but that they may miss having, say, a nut milk latte in the morning. That latte would not be allowed on a traditional clean fasting protocol, but dirty fasting may allow it.