Original sentence: The 5:2 diet, also written as 5/2 diet, is a fad diet which involves severe calorie restriction for two non-consecutive days a week and normal eating the other five days, which originated and became popular in the UK, and spread in Europe and to the USA
Edited sentence: Some claim the diet is effective, while others argue that it is a fad.The 5:2 diet, also written as 5/2 diet, is a controversial diet.The diet involves severe calorie restriction for two non-consecutive days a week and normal eating the other five days, which originated and became popular in the UK, and spread in Europe and to the USA