The structure of this diet is quite simple – for any 2 days of the week (eg. Monday and Thursday) consume fewer calories (500 calories for women instead of around 2000 calories/ 600 calories for men instead of 2500 calories). The ‘fast’ days focus more on protein-based foods and fruits/vegetables. The individual is then free to eat their regular unrestricted diet on the 5 non-fast days. 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. Research has shown that the weight loss and anti–aging health benefits which come from this diet are related more to the changes which take place in the body as a result of fasting, rather than being linked to the reduction in calories on the fast days. These short fasts lead the body into a metabolic state which triggers repair and recovery at a cellular level. This influences various hormones which are
circulating and the digestive system and related organs gets 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.
Is 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 2 days a week. On the other 5 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 1 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 Fast diet is actually good for health.
What would our diets be missing if we were to stick to the 5-2 Fast diet?
As a nutritionist, I am always wary of a diet which says that you can eat whatever you like on the other 5 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 quality supplement (such as Vital Greens) is an ideal product for individuals following the 5-2 Fast diet as it provides a broad cross-section of vitamins, minerals and food-based nutrients without making a significant impact upon calorie intake.
What could be the side effects of going on a diet such as this?
There appears to be many positive side effects as noted above and very few negative side effects from following the 5-2 Fast diet. 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.
It is essential that the 5-2 Fast 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.
What should our daily food plan look like on both fast and non-fast days?
A typical day may begin with a breakfast or lunch of 100g of Cottage Cheese, 1 pear and 1 fig followed by a dinner of baked fish served with a poached egg and asparagus. Meals on the fast days should contain a reasonable amount of protein as this help to give the stomach a sense of fullness.
On non-fast days, I recommend a balanced diet which contains plenty of vegetables, good quality protein, nuts, seeds, wholegrains, beans, legumes and fruit. For optimal health, sugar and ‘white’ carbs are best kept to a minimum.
For more information about the 5-2 Fast diet, take a look at The Fast Diet by Dr Michael Mosley and Mimi Spencer. This book clearly outlines how to approach the 5-2 Fast diet and provides examples of suitable fast-day meals.
Elspeth Stewart BSc(Hons) BANT CNHC is Vital Health Europe’s in-house Nutritional Therapist. She works with a range of clients to optimise health looking at goals including performance nutrition, digestive health, low energy and weight management. She also writes for nutrition/health magazines and lectures with CNELM/Middlesex University. Elspeth has completed post-graduate training with the Institute for Functional Medicine and CNELM’s ‘Competitive Athlete’.
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