If the 5:2 seems like too much work, there is an easier way to stay trim, get smarter and live for longer, apparently.
The scientists created a new food plan, titled the Fasting Mimicking Diet (FMD), in order to test the effects of calorie restriction, while ensuring participants consumed vitamins and minerals needed for a healthy body.
On the first day of the study, 19 volunteers ate 1,090 calories made up of 10% protein, 56% fat and 34% carbohydrate.
Their diet was then restricted to 725 calories on the second to fifth days, made up of 9% protein, 44% fat and 47% carbohydrate
After that, the participants returned to their normal diets for the next three weeks, before repeating the five day FMD the following month, and so on.
They were not asked to change their diet at all during the "normal diet" 25 days per month, yet still saw positive changes.
Notably, the FMD appeared to decrease amounts of the hormone IGF-I, which is a promoter of ageing and has been linked to cancer susceptibility.
"It's about reprogramming the body so it enters a slower ageing mode, but also rejuvenating it through stem cell-based regeneration. It's not a typical diet because it isn't something you need to stay on," lead researcher Professor Valter Longo said in a statement.
"If the results remain as positive as the current ones, I believe this FMD will represent the first safe and effective intervention to promote positive changes associated with longevity and health span, which can be recommended by a physician."
This isn't the first study to suggest fasting for a limited period of time may be beneficial to health.
Fasting has previously been linked to helping protect the brain against Alzheimer’s and Parkinson’s disease.
A 2014 study also lead by Professor Longo found that fasting for at least two days per month regenerates immune systems damaged by ageing or cancer treatment.
The latest research was published in the journal Cell Metabolism on 18 June.