Protein-sparing modified fast
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, .8-1.2 g per pound of lean 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, organs, 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 lean body mass and 67.5 pounds of fat, and weight trains three times 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 supplemention (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 are generally not recommended on this diet since whole foods lead to better satiety and this is an important factor on a very low calorie diet, though casein powder could be considered due to its ability 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 generally calculated based on lean body weight and adjusted based on activity level, but generally results in a net daily intake of well under 1000 calories. For an average male with a TDEE (total daily energy expenditure) 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 on a PSMF must typically consume supplements to avoid the nutritional deficiencies inherent in such an extreme and low-calorie diet. These include essential fatty acid supplements 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 augment a healthy diet, is inadequate - for example, someone on a PSMF needs significant amounts of minerals such as sodium and potassium. Potassium intake, for instance, has been recommended in general for both men and women to be at 4,700mg a day. Lyle McDonald, in particular, recommends supplementing 3-5 g of sodium, 1 g of potassium (typically as potassium citrate), 500mg of magnesium (magnesium citrate), and 600mg of supplemental calcium.
each pound of fat can supply about 31 calories energy to the body/pound of body fat. 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.
