5:2 Diet – Is Intermittent Fasting the Key to Good Health?

single pea in the middle of a white plate, knife and fork

The Horizon: Eat, Fast and Live Longer programme on BBC Two last week provided a fascinating look at the health benefits of intermittent fasting.

Presenter Michael Mosley set himself the challenge of wanting to to live longer, stay younger and lose weight while making as few changes to his life as possible.  To help him achieve his goal he went in search of world experts who are trying to combat the effects of ageing.

With a body fat ratio of 27%, and abdominal fat in particular, increasing his risk of cancer, Type 2 Diabetes and cardiovascular disease, Dr Mosley soon realised that his normal Western diet is seriously undermining his health.

Not keen on following a permanent calorie restricted diet – which has been shown to extend life expectancy in animals – he set out to discover if there are other ways to improve his health.

The Role of Growth Hormone IGG-1

The programme revealed the important link between a growth hormone called IGF-1 (insulin-like growth factor) and longevity in humans. High levels of IGF-1 seem to lead to accelerated ageing and age-related diseases, while low levels protect against disease.

The amount of protein we eat affects the levels of IGF-1.  It keeps our bodies in ‘go-go mode’, with cells constantly reproducing. This is important while we are growing but less so later in life.  It is only when IGF-1 levels drop that our body is able to switch from growth mode into repair mode. This can be achieved by cutting calories and protein intake, but can be fast-tracked through fasting.

Intermittent Fasting

Dr Mosley then went on to try different approaches to fasting beginning with four day fast, which he found quite difficult to incorporate into a busy lifestyle. He also tried Alternate Day fasting (ADF) which involves eating what you want one day, followed by a very restricted diet (fewer than 600 calories) the next. On non-fast days you can eat what you like.

The approach which worked the best for him was a variation of ADF called the 5:2 diet. This meant eating normally 5 days a week, then two days a week eating 500 calories if you are a woman, or 600 calories if you are a man.

Dr Mosley found that fasting on Tuesday and Thursday each week, rather than two consecutive days worked well for him. He had a breakfast of eggs and ham followed by dinner of fish and vegetables with only water and herbal teas in-between.

At the end of 5 weeks, Dr Mosley had lost nearly a stone in weight and his blood markers, like IGF-1, glucose and cholesterol, had improved.

Medical Advice and Considerations about Fasting

The current advice is to only fast under medical supervision or in a clinic. And for many people, such as pregnant women or diabetics on medication, fasting could be dangerous.

By the end of the programme I was certainly convinced of the health benefits of fasting and excited by the possibility of losing weight and improving my health. But I do have my concerns about going for long periods without food, especially as I suffer from low blood sugar and am used to eating at regular intervals. I also don’t really fancy feeling hungry, faint and tired and am worried that it will interfere with my ability to work and think clearly. At this stage I want to do a little more research and preparation before I give it a go.

What about you? Have you tried fasting? Do you follow a calorie restricted diet?  I’d love to hear about your experiences. Please get in touch and  leave a comment below.


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