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 associated with fad diets, and the individuals who develop and promote these programs often profit handsomely.
A competitive market for "healthy diets" arose in the nineteenth 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
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
Most people (as high as 98% in some descriptions) of people who diet using these diets in order to lose weight gain it back within 5 years; fad diets fail because many of them are not sustainable, and people revert to former eating habits when the diet fails.
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
Mainstream diet advice
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. Knowledge in this case is not, as of yet, power; would that it were so.
List of fad diets
- The 4-Hour Body
- 5:2 diet
- Alkaline diet
- Baby Food Diet
- Blood type diet
- Cabbage soup diet
- Detox diet
- Dukan Diet
- Grapefruit diet
- Israeli Army diet
- KE diet
- Master Cleanse
- Morning banana diet
- Paleolithic diet
- Pritikin Diet
- Scarsdale medical diet
- South Beach Diet
- Low-carbohydrate diet 
- High carb/low fat diets
- Food combining
- Liquid diets
- Diet pills, supplements and herbal remedies
- "Fact Sheet—Fad diets" (PDF). British Dietetic Association. 2014. Retrieved 12 December 2015.
- Flynn MAT (2004). Gibney MJ, ed. Chapter 14: Fear of Fatness and Fad Slimming Diets. Public Health Nutrition. John Wiley & Sons. pp. 236–246. ISBN 978-1-118-69332-2.
- Roy, Heli. "Fad Diets Defined" (PDF). Pennington Nutrition Series. Pennington Biomedical Research Center i.
- Fitzgerald M (2014). Diet Cults: The Surprising Fallacy at the Core of Nutrition Fads and a Guide to Healthy Eating for the Rest of US. Pegasus Books. ISBN 978-1-60598-560-2.
- Paradowski, Robert J. (2015). "Nutrition and Science". In Holbrook, J. Britt. Ethics, Science, Technology, and Engineering: A Global Resource, Vol. 3 (2nd, online ed.). Macmillan. pp. 297–301.
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.
- Jennifer Robbins, Silvina Pugliese, Diana Cullum-Dugan, Carine Lenders, Kathy Gorman Ireland Popular Diets Page accessed Jan 28, 2016
- What to Eat. New York: North Point Press (Farrar, Straus and Giroux). 2006. p. 611. ISBN 978-0-86547-738-4.
- "Nutrition for Weight Loss: What You Need to Know About Fad Diets". familydoctor.org. August 2016. Retrieved December 21, 2016.
- Tina Gianoulis, "Dieting" in the St. James Encyclopedia of Popular Culture Ed. Thomas Riggs. Vol. 2. 2nd ed. Detroit: St. James Press, 2013. p106-108. ISBN 978-1-55862-847-2
- Alters S, Schiff W (22 February 2012). Chapter 10: Body Weight and Its Management. Essential Concepts for Healthy Living (Sixth ed.). Jones & Bartlett Publishers. p. 327. ISBN 978-1-4496-3062-1.
- Katz DL, Meller S (2014). "Can we say what diet is best for health?". Annu Rev Public Health. 35: 83–103. doi:10.1146/annurev-publhealth-032013-182351. PMID 24641555.
- Hiatt, Kurtis. 1 March 2011, U.S. News & World Report, "'The 4-Hour Body'—Does It Deliver Results?".
- Collins, Sonya. "Alkaline Diets". WebMD. Retrieved 13 May 2016.
- Wait, Mariane. "The Baby Food Diet Review". WebMD. Retrieved 13 May 2016.
- Crosariol, Beppi. 9 January 2014,The Globe and Mail, "Feeling frugal after the holidays? Try these 11 affordable wines". Accessed 3 February 2014.
- webmd.com, 22 April 2011, "Are Fad Diets Worth the Risk?". Accessed 3 February 2014.
- Forbes, Gilber, American Academy of Pediatrics, 1980. "[Food Fads: Safe Feeding of Children http://pedsinreview.aappublications.org/cgi/reprint/1/7/207]" Pediatrics in Review. 1980;1:207-210. doi:10.1542/10.1542/pir.1-7-207.
- Sandra Bastin for University of Kentucky Extension Service. August 1998; revised March 2004. University of Kentucky Extension Service: Fad Diets
- Jonathan. "How to Spot Fad Diets". ahm Health Insurance. Retrieved 2012-07-25.
- news.com.au. 8 January 2014, "The worst diets of 2013 - and the best for 2014". Accessed 3 February 2014.
- Newman, Judith. "The Juice Cleanse: A Strange and Green Journey" (PDF). New York Times. New York Times. Retrieved 6 May 2016.
- Toyama, Michiko. Time, 17 October 2008, "Japan Goes Bananas for a New Diet" Accessed 1 July 2011.
- "Caveman fad diet".
- Frassetto, L.; Schloetter, M.; Mietus-Synder, M.; Morris, Jr., R.; Sebastian, A. (2009). "Metabolic and physiologic improvements from consuming a paleolithic, hunter-gatherer type diet" (PDF). European Journal of Clinical Nutrition. 63: 947–955. doi:10.1038/ejcn.2009.4. PMID 19209185. Retrieved 13 May 2016.
- Fad Diets Sandra Bastin, Ph.D., R.D., L.D. Cooperative Extension Service. University of Kentucky - College of Agriculture. March 2004. Retrieved August 28, 2015
- Dr. Paul Martiquet, Medical Health Officer, Vancouver Coastal Health. Muscles for brains: How fad diets can hurt you.
- Jane E Brody for the New York Times. June 3, 1981 Personal Health: Another Entry in the Annals of Fad Diets
- Southern Nevada Health District. 2015 Back to the 80s: Fad Diets
- DeBruyne L, Pinna K, Whitney E (2011). Chapter 7: Nutrition in practice — fad diets. Nutrition and Diet Therapy (8th ed.). Cengage Learning. p. 209. ISBN 1-133-71550-8.
'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 ...
- "People to watch". Nature Medicine. 12 (1): 29–29. 2006. doi:10.1038/nm0106-29. ISSN 1078-8956.
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.
- "Fad diets: Low Carbohydrate Diet Summaries" (PDF).
- Cohen, Larry et al. Prevention Institute, San Jose State University. "The O Word: Why the Focus on Obesity is Harmful to Community Health". Accessed 3 February 2014.
- Daniels, June RN, MSN. Nursing: December 2004 - Volume 34 - Issue 12 - p 22–23, "Fad diets: Slim on good nutrition". Accessed 3 February 2014.