Fasting has become extremely popular in contemporary nutrition, fitness, and diet communities because of its efficacy for weight loss, protection and promotion of lean muscle mass, and overall support of vibrant, whole body health. It is also popular because, while the diet and nutrition industries tend to focus on which foods to eat, often in specific quantities or combinations, fasting pivots the focus to when foods are consumed.

There are several methods of fasting. Some plans are temporary and consist of withholding solid foods entirely and reducing caloric intake substantially, during which you consume only liquids like bone broth and fruit-infused water, for three to five days. On the other hand, intermittent fasting requires withholding solid foods or calories within certain daily or weekly parameters on a regular long-term schedule. An example of intermittent fasting (or IF) is restricting solid food for two non-consecutive days each week, such that you are eating only one 500-calorie meal on the restricted days, and eating normally the rest of the week. There are also daily practices of eating during certain windows of time and abstaining from calories the rest of the day.

This book explores a fasting strategy which proposes consuming your daily calories during an eight-hour window, and restricting solid foods and substantial calories for the remaining 16 hours of the day: the 2-Meal-Day plan. This eating pattern is also referred to as the 8:16 fast, and shares similarities with Martin Berkhan’s "Leangains" protocol. The 8:16 strategy is credited with being one of the easiest IF models to adopt, as well as offering some of the most noticeable and lasting health and weight loss results.