A protein-sparing modified fast (PSMF) is a very low calorie diet with some protein, fluids, and vitamin and mineral supplementation. The diet is to last about eight months. While people often lose weight they often regain it afterwards. PSMFs were first designed in the 1970s. Health concerns include dehydration being a health concern, hence fluids, vitamin and mineral (potassium, magnesium, sodium, and calcium) supplementation is mandatory and doctor’s supervision is recommended. Since PSMF is minimal to no fat, gallbladder stones can be exacerbated from rapid weight loss, and it is recommended to at least obtain a minimum amount of fat daily for this reason. PSMF diets consist of foods that are naturally rich in good-quality protein (chicken breast, lean beef, tuna, egg white, ham,
Complete fasting produces the largest possible calorie deficit of any diet. Long-term fasting is extremely muscle sparing, as the body is designed to burn pure fat in the absence of exogenous calories of any kind. It should not be done without full understanding of the risks, but can be very effective. A PSMF attempts to separate the muscle from wasting effects while still eliminating fats and carbohydrates. Typically, depending on activity level, .8-1.2 g per pound of body mass (not total body weight) is taken. Protein beyond this minimum amount is also eliminated, as the body would use it for energy. Further lean body mass (muscle, organ, etc.) are spared through resistance training and limiting aerobic activity. For example, for a 225-pound male with 30% BF, and thus, 157.5 pounds of body weight and 67.5 pounds of fat, and weight trains for a week, he would consume 1.0 g per lb of LBM * 157.5 lb of LBM = 157.5 g of protein which is 630 calories / day. With a fish oil supplementation (40 calories), and some minimal fat which is inherent in almost all foods, the total caloric intake could be around 800 calories / day. Protein powders is an important factor in a very low calorie diet, though casein powder could be considered to be able to slow down digestion. Low calorie vegetables are required on the diet for the bulk, and fiber and carbohydrate-rich vegetables like corn, carrots, potatoes, etc. must be avoided on this diet. Any calorie-free fluids are permitted, including water, coffee, tea, and diet drinks. The amount of protein consumed varies by individual. It is based on 1000 calories and is based on 1000 calories. For an average male with a total daily energy expenditure (TDEE) of 2500 calories / day, and a caloric intake of 1000 calories / day, that would mean a caloric deficit of 1500 calories / day. Over 7 days, that would be 10,500 calories lost, and 3 pounds of weight (and up to 3 pounds of fat since 1 pound of fat is 3500 calories of energy) lost. In addition to lean protein, people have been found to be particularly sensitive to the nutritional deficiency inherent in such an extreme and low-calorie diet. These include essential fatty acids that have EHA and DHA in them (typically obtained from fish oil capsules), vitamins, and minerals typically potassium, magnesium, sodium, and calcium. A general multivitamin supplement, designed to increase a healthy diet, is inadequate – for example, which has significant PSMF requirements for sodium and potassium. Potassium intake, for instance, at 4,700 mg a day Lyle McDonald, in particular, recommends supplementing 3-5 g of sodium, 1 g of potassium (typically as potassium citrate), 500 mg of magnesium (magnesium citrate) and 600 mg of supplemental calcium. It is highly recommended to limit how long it is to PSMF diet for hormonal and energetic reasons. In general, people who are more obese can stay on the PSMF diet. As one’s body fat percentages decrease, it becomes more important than a few weeks. Example) A 300-pound person at 40% BF has 120 pounds of fat, and some research indicates that each pound of fat can supply about 31 calories to the body. Thus, this person could theoretically produce up to 31 calories / lb of fat * 120 pounds of fat = 3,720 calories from his fat reserves in a day. A 160-pound person at 10% body fat, however, with 16 pounds of fat could only produce 31 calories / lb of fat * 16 pounds of fat = 496 calories from his fat reserves.