Thought Leadership

The 5:2 way of eating

By Colin Walls

I do not do diets in the sense of weight loss programs. We all have a “diet” – the combination of foods that we eat – and I have always advocated as much variation as possible. Although I do eat things that are less good for me, I am conscious of what constitutes a healthy diet. I like to avoid food with additives, which can be challenging, as I wrote about a while back. When I was younger, I might have been described as “skinny”, but time has taken its toll and, although I am far from being fat, I could do with rearranging my weight a little.

I recently encountered the 5:2 diet …

The 5:2 diet – or Way of Eating [WOE is the amusing acronym] as its advocates prefer – is not simply a way to lose weight. It is a change in the approach and attitude to food and eating, which has a variety of benefits, where weight loss is just one possibility.

The approach to food – in the Western world at least – has changed drastically in recent years. We moved from a 3 meals a day regime to one where, although that structure might still be considered “normal”, the meals are supplemented by continuous snacking in the course of the day. Many people get as much as half their daily intake of calories from food intake that would not be considered a meal. The result is that the average calorie intake across the population is rising, with the obvious results. Although the idea of 3 square meals and nothing in between may seem traditional, it is really a new idea; humans have only been eating this way for a few hundred – perhaps a couple of thousand – years, since agriculture first started to be practiced.

Our bodies have not had time to evolve to accommodate this change. Evolution is a very slow process. Our species spent millions of years evolving to accommodate a very different approach to food. Early man was a hunter/gatherer. The result was food alternated between being plentiful [when a woolly mammoth had just been hunted] for short periods, interspersed with longer periods of being in short supply. This is commonly called “feast and famine”. It is not surprising that much research shows that our bodies are good at accommodating periods of very low food intake [fasts]. In fact, instead of just being tolerated, such fasting can even be shown to be directly beneficial. It is almost like exercising your digestive system [and all the other systems that lead on from it] is like exercising your muscles; the more you do it, the stronger you get.

Many people, and even religious groups, regard fasting as a good idea or a requirement. Unfortunately, such practices are often extreme. Most of us are not keen on the idea of eating nothing for a day/week/month. Even the idea of consuming nothing in the hours of daylight is very hard to follow. So, how can one get the benefits of fasting without such suffering? The answer is intermittent fasting, which where 5:2 comes in.

I am experimenting with the 5:2 WOE because it makes a lot of sense to me and the science behind it sounds reasonable. As I said before, I do not really want/need to lose much weight. However, I would like to reduce my waist size a little, as this is the parameter which seems to be related to a number of health conditions [type 2 diabetes being a good example]. The idea is that, for 5 days a week, you eat whatever you want. For the other days, you can still have any kind of food that you want, but your total calorie intake should not exceed 600/500 calories [for men/women respectively]. Also it is recommended that you go for a 16 hour period without any significant calorie intake; this is not so hard, as a lot of that time you will be asleep.

Most people who adopt 5:2 report weight loss after a few weeks. They also report feeling better overall. It is common to have a target weight and, when one has reached that, it can normally be sustained by only fasting on one day each week.

So, how does this really work? As far as I can tell, the weight loss that many people experience cannot be fully explained by the reduced calories for two days. I have already observed in myself a greater awareness of what I eat on the other days. I do not feel restricted on those days, but I can imagine that the enhanced awareness might cause me to avoid certain things. Although I have not yet experienced it, many followers of 5:2 report that their appetite for large portions is cut back, while their enjoyment of food is undiminished. I think that this must be the real factor in weight control.

I do find the fast days challenging, but not that hard – there is always the knowledge that the next day is “normal”. And I enjoy the normality of the other days. Yes, this cookie is 300 calories. And?

I am doing 5:2 for a month [August] to see how I feel. I already know that I can manage the low calorie intake without fainting or anything. I do not even find myself exceptionally hungry the following day. At the end of the month, I will review and tentatively plan to go on for the rest of the year. If I do lose weight, I may move to one fast day per week, but that will require at least 3Kg to go. I will also take breaks for vacation etc., but give it my best shot overall.

There! I wrote it down, so now I am committed. I will report back.

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This article first appeared on the Siemens Digital Industries Software blog at