The Diet Of The Moment: What Do The Experts Really Think About The 5:2?

Everywhere we go we hear people talking about the 5:2 diet, and the term 'fasting day' has begun to crop up in day-to-day conversation. But what do the experts have to say about this weight loss phenomenon?


Everyone has tried out the 5:2 diet. The chances are that one of your colleagues or friends is on a fast day right now. But is the 5:2 a healthy approach to weight loss? Does fasting have any worrying side effects? We picked the brains of Vital Greens’ Elspeth Stewart to see what she really thought of the diet du jour.

Why do you lose weight so quickly on the 5:2 diet?
The structure of this diet is quite simple – for any two days of the week (eg. Monday and Thursday) consume fewer calories (500 calories for women instead of around 2000 calories). The fast days can be moved around to suit a busy lifestyle. Because the duration of each fast is quickly over and it is possible to enjoy food with family and friends on non-fast days, this approach to weight management is reported to be quite sustainable by the majority of people who try it.

The short fasts lead the body into a metabolic state which triggers repair and recovery at a cellular level. This influences various hormones and gives the digestive system, and related organs, some time to rest, especially the pancreas, the gland which produces insulin in response to carbohydrates and sugar. This helps the body to become more sensitive to insulin, which is one of the most important aspects of not only weight loss but also reducing the risk of diabetes.

Secondly, through regular, short term fasts, individuals report that on their ‘non-fast days’ they have better sense of control over what they eat, rarely eat out of boredom and have a tendency to choose foods which are more healthy.

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But isn’t losing weight this quickly unhealthy?
Often, rapid weight loss can be problematic as people find they gain rebound weight as soon as they return to ‘normal’ eating patterns. The 5:2 fast diet is a little different because the calorie restriction only happens on two days a week. On the other five days of the week, there is no diet, no calorie counting and normal eating, including balanced enjoyment of treats, which is encouraged. This programme isn’t presented as a short term solution but rather a long term way of eating, although many individuals, once at their desired weight, choose to switch to a maintenance fast programme, with only one fast day per week.

An increasing body of research looking at people following this diet illustrates that it is not only very effective with weight loss but that, within a matter of weeks, it also brings about improvements to a range of markers associated with improved health, such as cholesterol, triglycerides, HbA1c, insulin and IGF1 (a growth factor associated with an increased risk of cancer). So rather than having negative health implications, the 5:2 diet is actually good for health.

THE 5:2 DIET: EVERYTHING YOU NEED TO KNOW

Are people on the 5:2 diet getting all the nutrients they need?
As a nutritionist, I am always wary of a diet which says that you can eat whatever you like on the other five days. I encourage clients to follow a balanced diet at all times. Plenty of vegetables, good quality protein, nuts, seeds, wholegrains, beans, legumes and fruit. By all means, enjoy the occasional treat but don’t make them an everyday occurrence. And, of course, food is not just about calories – healthy food also supplies nutrients and fibre. If food intake is reduced to 500 or 600 calories twice a week, then on these two days, the body is unlikely to reach the Recommended Nutrient Intake of vitamins and minerals. A supplement like Vital Greens is a great way to make sure you’re getting a broad cross-section of vitamins, minerals and food-based nutrients without making a significant impact upon calorie intake.

Will I be starving on the fast days?
The first couple of fast days can be a challenge, but, once used to the way it feels to have a sense of hunger, many individuals report that the fast days become not only bearable but enjoyable. Reports include feeling lighter, more alert, more energetic and awake.

What’s your overall advice when it comes to weight loss?
It is essential that the 5:2 diet is approached sensibly. Because of the fasting, it is not a diet recommended for anyone who has an eating disorder. The fast days should always contain the recommended amount of calories and the non-fast days should not be calorie restricted to ensure that over the week, sufficient calories are still consumed.

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