Food faddism and fad diet usually refer to idiosyncratic diets and eating patterns. They are diets that claim to promote weight loss or treat obesity by mechanisms other than calorie restriction.

The term "food fad" may also be used with a positive connotation, namely, to describe the short term popularity among restaurants and consumers of an ingredient, dish, or preparation technique.

Scientific view

Fad diets are diets that claim weight loss by mechanisms other than calorie restriction.

Many forms of food faddism and fad diets are supported by pseudo-scientific claims. Fad diets claim to be scientific but do not follow the scientific method in establishing their validity. Among the scientific shortcomings of the claims made in support of fad diets:

• not being open to revisions, whereas real science is
• observations that prompt explanations are used as evidence of the validity of the explanation

Some in the scientific community comment that food faddism is born of ignorance about basic scientific dietary facts. The evidence supporting weight loss enhanced by anything other than caloric restriction is lacking. There is also a lack of evidence to support that fad diets produce sustainable weight loss. Fad diets generally ignore or refute what is known about fundamental associations between dietary pattern and human health.

Fad diets

Belief in fad diets by adherents is often irrational. Many individuals who adhere to fad diets will not consider recommendations made by nutritionists and dieticians.

There are three categories of food fads. Some food fads incorporate a combination of