A protein-sparing modified fast or PSMF diet is a type of a very-low-calorie diet (<800 kcal per day) with a high proportion of protein calories and simultaneous restriction of carbohydrate and fat. [1] It includes a protein component, fluids, and vitamin and mineral supplementation. [2] [3]
PSMF diets can last for up to 6 months, followed by a gradual increase in calories over 6–8 weeks. [2]
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. [4] 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 in a process called gluconeogenesis. [5] Further lean body mass (muscle, organs, etc.) are spared through resistance training and limiting aerobic activity. [6] [7]
The concept of "protein-sparing modified fast" (PSMF) was described by George Blackburn in the early 1970s as an intensive weight-loss diet designed to mitigate the harms associated with protein-calorie malnutrition [8] and nitrogen losses induced by either acute illness or hypocaloric diets in patients with obesity, in order to adapt the patient's metabolism sufficiently to use endogenous fat stores as well as to preserve the protein contained in the body cell mass. [9] [10]
The "liquid protein" PSMF diet described in the book The Last Chance Diet in 1976, [11] motivates that the liquid protein diets of varying composition became widely popular. Three years later, in 1979, Isner published a report of 17 deaths associated with liquid protein VLCD, due to heart-related causes. [12] These serious effects caused a substantial concern about the safety of clinical use of PSMF and VLCD. As a result, a review was published that highlighted the differences between these liquid protein diets, arguing that the fatal diets typically used hydrolyzed collagen (gelatin) supplemented with the amino acid tryptophan for protein but that this omitted the other 8 essential amino acids; it further emphasized the importance of close medical monitoring during the fast and refeeding periods [13]
Instead of hydrolyzed collagen, modern medically supervised PSMF diets include foods of higher biological value, such as meat, fish, eggs, cheese, and/or tofu. [2] PSMF is used as a treatment for highly motivated patients to achieve rapid weight loss and usually is administered for 6 – 16 weeks. [10] [14]
Before an individual starts a PSMF diet, their doctor should order an electrocardiogram, to check for signs of heart disease and also will prescribe specific vitamins minerals and electrolytes to be taken daily as long as the diet persists. [2] [15]
Dieting is the practice of eating food in a regulated way to decrease, maintain, or increase body weight, or to prevent and treat diseases such as diabetes and obesity. As weight loss depends on calorie intake, different kinds of calorie-reduced diets, such as those emphasising particular macronutrients, have been shown to be no more effective than one another. As weight regain is common, diet success is best predicted by long-term adherence. Regardless, the outcome of a diet can vary widely depending on the individual.
Abdominal obesity, also known as central obesity and truncal obesity, is the human condition of an excessive concentration of visceral fat around the stomach and abdomen to such an extent that it is likely to harm its bearer's health. Abdominal obesity has been strongly linked to cardiovascular disease, Alzheimer's disease, and other metabolic and vascular diseases.
The Atkins diet is a low-carbohydrate fad diet devised by Robert Atkins in the 1970s, marketed with claims that carbohydrate restriction is crucial to weight loss and that the diet offered "a high calorie way to stay thin forever".
Weight loss, in the context of medicine, health, or physical fitness, refers to a reduction of the total body mass, by a mean loss of fluid, body fat, or lean mass. Weight loss can either occur unintentionally because of malnourishment or an underlying disease, or from a conscious effort to improve an actual or perceived overweight or obese state. "Unexplained" weight loss that is not caused by reduction in calorific intake or increase in exercise is called cachexia and may be a symptom of a serious medical condition.
A fad diet is a diet that is popular, generally only for a short time, similar to fads in fashion, without being a standard scientific dietary recommendation, and often making unreasonable claims for fast weight loss or health improvements; as such is often considered a type of pseudoscientific diet. Fad diets are usually not supported by clinical research and their health recommendations are not peer-reviewed, thus they often make unsubstantiated statements about health and disease.
Low-carbohydrate diets restrict carbohydrate consumption relative to the average diet. Foods high in carbohydrates are limited, and replaced with foods containing a higher percentage of fat and protein, as well as low carbohydrate foods.
Calorad Classic is a liquid protein weight loss supplement which was first introduced to the US and Canadian marketplace in 1984. It has been advertised on both television and radio. Calorad Classic is manufactured by NutriDiem and is marketed by several companies including Essentially Yours Industries and Nysante, all of which are headquartered in Canada.
The ketogenic diet is a high-fat, adequate-protein, low-carbohydrate dietary therapy that in conventional medicine is used mainly to treat hard-to-control (refractory) epilepsy in children. The diet forces the body to burn fats rather than carbohydrates.
Weight gain is an increase in body weight. This can involve an increase in muscle mass, fat deposits, excess fluids such as water or other factors. Weight gain can be a symptom of a serious medical condition.
Calorie restriction is a dietary regimen that reduces the energy intake from foods and beverages without incurring malnutrition. The possible effect of calorie restriction on body weight management, longevity, and aging-associated diseases has been an active area of research.
A healthy diet is a diet that maintains or improves overall health. A healthy diet provides the body with essential nutrition: fluid, macronutrients such as protein, micronutrients such as vitamins, and adequate fibre and food energy.
The Cambridge Diet was a very-low-calorie meal replacement fad diet developed in the 1960s. The diet launched with different versions in the US and the UK. The US version filed for bankruptcy and shut down shortly after the deaths of several dieters. The UK diet has also been known as the Cambridge Weight Plan, but is now known as The 1:1 Diet.
Protein–energy malnutrition (PEM), sometimes called protein-energy undernutrition (PEU), is a form of malnutrition that is defined as a range of conditions arising from coincident lack of dietary protein and/or energy (calories) in varying proportions. The condition has mild, moderate, and severe degrees.
A very-low-calorie diet (VLCD), also known as semistarvation diet and crash diet, is a type of diet with very or extremely low daily food energy consumption. VLCDs are defined as a diet of 800 kilocalories (3,300 kJ) per day or less. Modern medically supervised VLCDs use total meal replacements, with regulated formulations in Europe and Canada which contain the recommended daily requirements for vitamins, minerals, trace elements, fatty acids, protein and electrolyte balance. Carbohydrates may be entirely absent, or substituted for a portion of the protein; this choice has important metabolic effects. Medically supervised VLCDs have specific therapeutic applications for rapid weight loss, such as in morbid obesity or before a bariatric surgery, using formulated, nutritionally complete liquid meals containing 800 kilocalories or less per day for a maximum of 12 weeks.
A diabetic diet is a diet that is used by people with diabetes mellitus or high blood sugar to minimize symptoms and dangerous complications of long-term elevations in blood sugar.
A low-fat diet is one that restricts fat, and often saturated fat and cholesterol as well. Low-fat diets are intended to reduce the occurrence of conditions such as heart disease and obesity. For weight loss, they perform similarly to a low-carbohydrate diet, since macronutrient composition does not determine weight loss success. Fat provides nine calories per gram while carbohydrates and protein each provide four calories per gram. The Institute of Medicine recommends limiting fat intake to 35% of total calories to control saturated fat intake.
Weight management refers to behaviors, techniques, and physiological processes that contribute to a person's ability to attain and maintain a healthy weight. Most weight management techniques encompass long-term lifestyle strategies that promote healthy eating and daily physical activity. Moreover, weight management involves developing meaningful ways to track weight over time and to identify ideal body weights for different individuals.
George A. Bray is an American obesity researcher. As of 2016, he is a University Professor emeritus and formerly the chief of the division of clinical obesity and metabolism at Louisiana State University's Pennington Biomedical Research Center in Baton Rouge. He is also a Boyd Professor emeritus at the Pennington Center, and a professor of medicine emeritus at the Louisiana State University Medical Center.
Weight Watchers or WW is a commercial program for weight loss based on a point system, meals replacement and counseling.