It's the diet that claims to let you have your cake – and eat it. And intermittent fasting isn't as scary as it sounds.
Also nicknamed the 5:2 diet, the regime follows a relatively straightforward process allowing you to eat flavour-filled foods five days a week, whilst fasting on the other two. Similar to the alternate-day diet and the 80:20 diets favoured by A-listers such as supermodel Miranda Kerr, the 5:2 plan promises to be the easiest fasting regime to adapt into your regular lifestyle.
Essentially, on two (non-consecutive) days, you are recommended to consume just 500 calories (600 for men). While it's important to not overeat on the other days when regular eating resumes, you are given free reign on your choice of foods – even those considered to be high-fat.
Fasting is not recommended if you are pregnant or are on medication for diabetes. Consult your GP before embarking on any diet.
The diet first went mainstream via a BBC Horizon documentary called Eat, Fast and Live Longer, where health journalist Dr Michael Mosley took the 5:2 diet to the challenge.
The most obvious downside is that, when fasting, calorie restriction means barely reaching a few handfuls of fruit and vegetables alongside a couple of eggs and ham to see you through the day. But Dr Mosley recently explained that "after a settling-in period, it has become quite easy" to adjust the diet to your regular lifestyle.
Six weeks after starting the 5:2 diet a full medical exam showed "impressive" results. The doctor lost nearly a stone, reduced his body fat by 25 per cent in addition to improving his blood sugar and cholesterol levels.
Researchers also claim that the diet could significantly slow the ageing process.
The theory behind this belief centres itself around the hormone called IGF-1 – an insulin-like growth factor which leads to accelerated ageing and cell production. Although crucial in early life, high levels of this hormone in adulthood increase the risk of cancer, weight gain and can be attributed to the high-protein diets that are common in the western world.
While crash-diets or skipping meals often fail in the early stages, intermittent fasting tricks the body out of storing fat and is even found to reduces levels of IGF-1. Through this the body is sent into “repair mode”, focusing on restoring damaged cells rather than producing new ones and thus using up more energy.
However, although many have successfully lost weight in a relatively short period while adopting fasting diets, there is no evidence, as yet, to show that people are able to stick to the plan long-term.