The UK doctor and television celebrity developed the diet while researching a drug-free way to control his diabetes, discovering the benefits of intermittent fasting after numerous experiments with strict fasting regimes. ; According to Mosley, "The tradition of feast and fast is built into our genes. So fasting, or at least involuntary fasting, going without food for periods of time, would have been incredibly normal. And that is incredibly abnormal now."
The 5:2 Diet incorporates two non-consecutive days of very low-calorie eating, followed by five days of normal, non-restrictive eating. ; While just 500-600 calories are consumed on fasting days, regular eating routines can be followed the rest of the time. ; According to proponents of the diet, the 5:2 rhythm not only makes the diet easy to follow but also provides all the benefits of long-term fasting.
A 2014 study by Longo and Mattson shed light on the role of intermittent fasting in adaptive cellular responses. ; Not only was fasting found to reduce oxidative damage and inflammation, it was also shown to optimise energy metabolism and bolster cellular production. ; In rodents, intermittent fasting was shown to protect against diabetes, cancers, heart disease and neurodegeneration, while in humans it was shown to reduce obesity, hypertension, asthma, and rheumatoid arthritis.
Other research by Krista Varady from the University of Illinois in Chicago looked at the way fasting impacts a range of chronic diseases. ; According to Varady, intermittent fasting can modulate several risk factors known to bring about chronic diseases, including cardiovascular disease, type 2 diabetes, and cancer. ; Not only is intermittent fasting just as effective as caloric restriction, according to Varady, but benefits also include increased insulin sensitivity and a slight increase in longevity.
While the health benefits of fasting are still controversial, intermittent fasting has been shown by Longo and Mattson to switch on the DNA repair genes that make our body go from "growth mode" to "repair mode." ; According to Mosley, the switch between growth and repair is key, with intermittent fasting an effective way to go back to more natural rhythms. ; "It is the periods without food which your body has the opportunity to do spring cleaning." says Mosley, "Because the rest of the time, it just wants to get on with life."