A fad diet or diet cult:9–13 is a diet that makes promises of weight loss or other health advantages such as longer life without backing by solid science, and in many cases are characterized by highly restrictive or unusual food choices.:296 Celebrity endorsements are frequently used to promote fad diets, which may generate significant revenue for the creators from the sale of associated products.
A competitive market for "healthy diets" arose in the 19th century developed world, as migration and industrialization and commodification of food supplies began eroding adherence to traditional ethnocultural diets, and the health consequences of pleasure-based diets were becoming apparent.:9 As Matt Fitzgerald describes it:
This modern cult of healthy eating is made up of innumerable sub-cults that are constantly vying for superiority. ...Like consumer products in commercial markets, each of these diets has a brand name and is advertised as being better than competing brands. The recruiting programs of the healthy-diet cults consist almost entirely of efforts to convince prospective followers that their diet is the One True Way to eat for maximum physical health.... The specific cult whose "science"-backed schtick a person finds most convincing usually depends on his or her identity biases.:9–13
The modern fad diet originated in the 1930s. These diets are generally restrictive, and are characterized by promises of fast weight loss or great physical health,:9 and which are not grounded in sound science.:12 One sign of fad diets is a requirement to purchase associated products and pay to attend seminars in order to gain the benefits of the diet.
These diets attract people who want to lose weight quickly and easily and keep that weight off or who want to be healthy and find that belonging to a group of people defined by a strict way of eating helps them to avoid the many bad food choices available in the developed world.:11
Fad diets may be based completely on pseudoscience (e.g., "magical fat-burning" foods or notions of vitalism); most fad diets are marketed or described with exaggerated claims, not sustainable in sound science, about the benefits of eating a certain way or the harms of eating other ways.:33,74, 80, 155
According to Boston University School of Medicine, 98% of people who lose weight regain it within 5 years. Many diets fail to produce lasting weight loss because dieters revert to old habits after the end of the diet, many diets are not sustainable, and deprivation of certain foods leads to binge eating.
The basic principles of good diets are so simple that I can summarize them in just ten words: eat less, move more, eat lots of fruits and vegetables. For additional clarification, a five-word modifier helps: go easy on junk foods. Follow these precepts and you will go a long way toward preventing the major diseases of our overfed society—coronary heart disease, certain cancers, diabetes, stroke, osteoporosis, and a host of others.... These precepts constitute the bottom line of what seem to be the far more complicated dietary recommendations of many health organizations and national and international governments—the forty-one “key recommendations” of the 2005 Dietary Guidelines, for example. ... Although you may feel as though advice about nutrition is constantly changing, the basic ideas behind my four precepts have not changed in half a century. And they leave plenty of room for enjoying the pleasures of food.:22
David L. Katz, who reviewed the most prevalent popular diets in 2014, noted:
The weight of evidence strongly supports a theme of healthful eating while allowing for variations on that theme. A diet of minimally processed foods close to nature, predominantly plants, is decisively associated with health promotion and disease prevention and is consistent with the salient components of seemingly distinct dietary approaches. Efforts to improve public health through diet are forestalled not for want of knowledge about the optimal feeding of Homo sapiens but for distractions associated with exaggerated claims, and our failure to convert what we reliably know into what we routinely do.
Even in developed countries, citizens have the right to be provided with good food, but in the United States, for example, many consumers have either wasted their money or harmed their health by various food and diet fads. Many nutrition scientists consider it unethical for “medical quacks” to be making large amounts of money in this way from gullible Americans.
To get started on the numbers, let’s leave the supermarket for a moment and take a detour into the realm of popular diets, beginning with the low-carbohydrate so successfully promoted by the late Dr. Robert Atkins. In the summer of 2003, when the low-carbohydrate diet craze was nearing its peak (but nobody knew that yet), I attended a meeting in Aspen, Colorado, sponsored by Fortune magazine. At dinner one night, I was seated next to a healthy-looking and only slightly overweight business executive whose table behavior reminded me of my kids during the worst of their picky eating phases. ...Only then did he dig into the buttered filet mignon. Just my luck, I thought, another Atkins dieter. In a minute he will be telling me how much weight he has lost eating this way. Sure enough. Pleased as could be, he said he had just lost eleven pounds in two weeks on the Atkins diet. Off duty as I was trying to be, I did not point out that his vegetables had only tiny amounts of sugars, too little carbohydrate to make any difference. I also did not point out that there was no way he could have lost that weight as body fat. ...
Some population groups seem to be especially wed to the gluten-free diet, with nearly 50% of 910 athletes (including world class and Olympic medalists) adhering to a gluten-free diet, mainly because of the perceived health and energy benefits.
People buy gluten-free food "because they think it will help them lose weight, because they seem to feel better or because they mistakenly believe they are sensitive to gluten."
'a fad diet by any other name would still be a fad diet.' And the names are legion: the Atkins Diet, the Cheater's Diet, the South Beach Diet, the Zone Diet. Year after year, 'new and improved' diets appear ...
James Hill wants Americans to shed pounds. But instead of promoting any one fad diet, he embraces most--Atkins, South Beach, grapefruit-only--as relatively effective ways to lose weight.