This is the summary of a BBC Horizon programme of the same name.
It got me interested enough in the 5:2 diet to want to give it a go – and I have never before considered such an action. Before giving an overview of the programme it’s worth pointing out that there’s no real focus on weight loss as such; rather it’s about longevity, avoidance of killer diseases, and general body health.
The programme started with the Sikh 101-year-old marathon runner. The secret of his success has been to eat a ‘half-portion’ diet for many years. He has had no operations and receives no regular medication.
There are clear links between food and longevity – not just what we eat – but how and when. In particular calorie restriction can lead to longevity. To be effective and sustainable it’s necessary that long term calorie restriction is is informed by nutritional intake: ‘calorie restriction on optimal nutrition’.
A man in his mid 50s has eaten 1900 calories a day for a decade: lots of fruit and veg. His body fat measure was 11.5% – presenter Michael Mosley’s (of similar age) was 27%.
The programme then discussed the negative presence of growth hormone IGF-1 in the body. It seems to be linked to protein intake, and there seems to be a link with cancer and diabetes.
It appears that IGF-1 can be reduced by cutting protein in the diet; or by ‘fasting’. In this sense fasting is for 3.5 days and doesn’t mean eating nothing at all. A 3.5 day fast can improve body make up, but the effect is temporary. For longer term benefit it would be necessary to fast – say – every 2 months or so.
With Alternate Day Fasting you eat normally every other day – and can eat pretty much what you like. On fast days you are restricted to 600 calories for men, 500 for women. This approach seems to have a positive effect on body make up and general health, and anecdotal evidence suggests that it really doesn’t matter what you eat on feed days, nor do people tend to gorge themselves on feed days.
Presenter Michael Mosley saw more practical appeal in the 5:2 diet, where you eat normally for 5 days, then reduce to 600/500 for the other 2. He maintained the diet for a trial 5 weeks, and found it was eminently do-able. He lost ‘over a stone’, body fat reduced from 27% to below 20%, IGF-1 dropped by 50%, and blood sugar and cholesterol levels were described as good.
Michael Mosley was impressed and moved, it’s fair to say !