Protein-sparing modified fast

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A protein-sparing modified fast (PSMF) is a very low calorie type of fad diet; it includes a protein component, fluids, and vitamin and mineral supplementation.[1][2] The diet is to last about eight months.[1] While people often lose weight, they frequently regain it afterwards.[1]

Health concerns include dehydration, hence fluids, vitamin and mineral (potassium, magnesium, sodium, and calcium) supplementation is mandatory and doctor's supervision is recommended. Since PSMF includes little or no fat, the rapid weight loss may cause gallstones. It is therefore recommended to consume at least a minimum amount of fat daily.[3] PSMF diets consist of foods that are naturally rich in good-quality protein and particularly extremely low in fats (chicken breast, extra lean beef, tuna, egg white, ham, cottage cheese)[4][unreliable medical source?]


The Last Chance Diet[edit]

PSMF diets were first devised in the 1969s.[1] The early "liquid protein" PSMF diet was described in the book The Last Chance Diet by osteopath Robert Linn. The diet consisted of a hydrolyzed collagen drink, water, vitamin supplements, and mineral supplements; nothing else.[5] The book sold well; more than 100,000 individuals tried Linn's diet. At least 17 dieters died suddenly, probably due to heart-related causes.[6] The true reason for the deaths is still not fully clear, even today.[7][8]

Modern PSMF diets[edit]

Modern medically-supervised PSMF diets are safer.[1] Instead of hydrolyzed collagen, they include foods of higher biological value, such as meat, fish, eggs, cheese, and/or tofu.[1] Also, nowadays, before an individual starts a PSMF diet, their doctor will order an electrocardiogram, to check for signs of heart disease.[1] Finally, the doctor will prescribe specific vitamins, minerals, and electrolytes, to be taken daily while dieting.[1]


A PSMF attempts to spare the dieter the health risks of a complete fast by introducing the minimum amount of protein necessary to prevent muscle-wasting effects, while still eliminating fats and carbohydrates. Typically, depending on activity level, 0.8–1.2 g of protein per pound of lean body mass (not total body weight) is consumed. Protein beyond this minimum amount is also eliminated, as the body would use it for energy.[citation needed] Further lean body mass (muscle, organs, etc.) are spared through resistance training and limiting aerobic activity.[9][10]

See also[edit]


  1. ^ a b c d e f g h Chang, J; Kashyap, SR (September 2014). "The protein-sparing modified fast for obese patients with type 2 diabetes: what to expect". Cleveland Clinic Journal of Medicine. 81 (9): 557–65. doi:10.3949/ccjm.81a.13128. PMID 25183847.
  2. ^ Gilman SL (2007). Linn, Robert (1933–). Diets and Dieting: A Cultural Encyclopedia. Routledge. p. 160. ISBN 978-1-135-87068-3.
  3. ^ Sisson, Mark. "High Fat Diet & Gallbladder Stones". Mark's Daily Apple. Retrieved November 13, 2017.
  4. ^ "PSMF Diet Program". Cleveland Clinic. Retrieved 2015-06-07.
  5. ^ Brozan, Nadine. "The Liquid Protein Diet Controversy". The New York Times.
  6. ^ See the 5 November 2018 comment at Talk:Protein-sparing modified fast. And see also: Isner, JM; Sours, HE; Paris, AL; Ferrans, VJ; Roberts, WC (December 1979). "Sudden, unexpected death in avid dieters using the liquid-protein-modified-fast diet: observations in 17 patients and the role of the prolonged QT interval" (PDF). Circulation. 60 (6): 1401–1412. doi:10.1161/01.CIR.60.6.1401. PMID 498466.
  7. ^ Brody, Tom (1999). Nutritional Biochemistry (2nd ed.). San Diego, California: Academic Press, Inc. Page 476.
  8. ^ Surawicz, B; Waller, BF (March 1995). "The enigma of sudden cardiac death related to dieting". Canadian Journal of Cardiology. 11 (3): 228–31. PMID 7889441.
  9. ^ Manninen, Anssi (2006). "Very-low-carbohydrate diets and preservation of muscle mass". Nutr Metab (Lond). 3: 9. doi:10.1186/1743-7075-3-9. PMC 1373635. PMID 16448570.
  10. ^ Bryner, Randy. "Effects of Resistance vs. Aerobic Training Combined With an 800 Calorie Liquid Diet on Lean Body Mass and Resting Metabolic Rate". ResearchGate. Retrieved July 10, 2017.