The question seems simple at first glance: what is a fad diet? This can be a little hard to answer since the technical answer and the common use answer are actually two different things. However between the two there is a general understanding of what exactly this type of diet is and what is generally meant when this term is used.
Technically, a fad diet is any diet or eating plan that becomes extremely popular for a short time, but then loses its popularity and fades. This doesn’t mean that no one uses it after this time, but it does mean that the general ground swell of support behind it dissipates. However, when many people use the term “fad diet,” they are also referring to diets that are dangerous, unproven, or any diet that has a general negative connotation. In other words, it’s not a safe long term weight loss plan.
These eating plans can become temporarily famous for a wide range of reasons. Some gain attention because a famous Hollywood star talks about it and then crazed fans follow. Others are based on claims from scientific studies, while some fad diets become huge literally because of overwhelming marketing by the company who profits from promoting it.
These are just a few of the many ways that fad diets come to be, but it’s important to remember that while not every diet plan labeled this way is terrible (there is still fighting over things like low carb diets, for example), normally this term is not a positive one overall.