The 5:2 diet or The Fast Diet has been on most dieters' lips in the past year. The Fast Diet book, written by Dr Michael Mosley and Mimi Spencer, reportedly became Amazon's best selling book last year, being allegedly used by various celebs from Jennifer Lopez and Beyonce to Benedict Cumberbatch.

How does the 5:2 diet work?

The idea behind the new 5/2 diet is simple: eating a healthy diet and consuming a regular number of calories for five days and fasting for two days. During the fasting days, women are allowed to consume 500 calories only while the limit for men is 600 calories. The two days of fasting don't have to be consecutive and don't have to be the same ones every week, so dieters can choose the days that work best for them and that don't interfere too much with their schedule.


Though there are no forbidden foods during the five days, dieters are encouraged to eat an abundance of fruits and vegetables, lean meats and avoiding sugar and simple carbohydrates. There is no need to count calories during the five days, however, if no progress is made after a few weeks, it is recommended to make sure one doesn't go over the daily recommended calorie allowance. After the desired weight loss goal has been hit, the proportion changes to 6:1, meaning six days of eating normally and only one day of fasting.

The Fast Diet Pros

The 5:2 diet is said to have impressive health benefits that go beyond weight loss. Calorie restriction has been shown to increase lifespan, which is why the idea of intermittent fasting has become popular in the first place. A 2012 study suggested that the diet might help prevent breast cancer and other types of cancers involving estrogen receptors. Furthermore, it is also believed that the diet might help prevent cognitive decline, however, further research is needed to see whether the conclusions are warranted.

The fact that during the fast days the digestive system is getting a longer period of rest is also seen as a benefit. However, the success of the diet can be explained more easily from a psychological standpoint. The diet is simple and doesn't have too many restrictions when it comes to the foods allowed. Moreover, the idea of not making massive adjustments that require a lot of self control day in and day out, make the principle attractive for other areas of life as well.

Healthy Food

5:2 Diet Cons

Among the possible side effects of the 5:2 diet are difficulty sleeping, bad breath, irritability, difficulty concentrating and decreased energy. Furthermore, it can be quite easy to develop nutritional deficiencies if the plan is not diversified enough. Moreover, severely decreasing calories might result in binging later on, though proponents of the diet say that it is unlikely. There is also a concern that the idea can be misused by those who are prone to developing eating disorders.

Who shouldn't try the fast diet?

The diet shouldn't be followed by children and adolescents, people with diabetes, pregnant women or women who are nursing, as well as those who have a history of eating disorders.

Read also:
The 1200 Calorie Diet
The Most Important Meal of the Day: How Many Calories for Breakfast

Photos: Thinkstock