PSMF Diet Program

General information

Obesity is a primary health concern and a risk factor for coronary heart disease, diabetes, gall bladder disease, arthritis, and peripheral vascular disease. Weight loss can make a significant contribution to improving general health and well-being. The Protein-Sparing Modified Fast (PSMF) is a medically supervised program designed for rapid weight loss and incorporates medical, nutritional, and behavioral components. The goal of this diet is to reach an appropriate body weight as determined by your physician and registered dietitian.

Carbohydrate, protein, and fat are the nutrients in food that provide energy for proper functioning, maintenance, and repair of the body. In addition to these three nutrients, the human body requires water, vitamins, and minerals for good health.

While on the PSMF program, only lean meat, seafood, poultry, and a limited amount of low-carbohydrate vegetables should be eaten. Carbohydrates and additional forms of fat are not allowed on this program. The high protein intake is to prevent the body from using its own protein stores in muscles, tissues, and cells for energy. Thus, the program is a “modified” fast.

Carbohydrates are usually the body’s primary source of energy. Since a very limited amount of carbohydrates are consumed, fat becomes the primary fuel source for the body. This rapid breakdown of fat produces ketones that spill into the urine, called ketosis. Ketones in the urine are desirable. While in ketosis, most people lose their appetite, which is a benefit of this program. A large amount of the water in your body is stored with carbohydrates. Since carbohydrate intake is severely limited and storage is severely depleted, dehydration is a health concern. To compensate, adequate quantities of fluid, sodium and taking a multivitamin/mineral supplement, calcium, magnesium supplement and prescription potassium are required each day. Eating foods that contain carbohydrates can take you out of ketosis, which not only means less weight reduction, but it can cause dangerous shifts in the body’s fluid and electrolytes.

Behavior modification

You will be asked to change your eating habits. Throughout the program, new behaviors will be introduced to encourage healthy habits. Your serious effort is required to change old eating habits, which will help you reach and maintain your desired weight. Your physician or registered dietitian may recommend an appointment with a psychologist to assist with behavior modification.

Appointment schedule (length of program based on amount of weight one needs/wants to lose)

Physician schedule:

Registered dietitian schedule:

Purpose of the appointment with the registered dietitian


When your goal weight is achieved, protein and dietary supplement intake will gradually be reduced while carbohydrates are reintroduced. This “refeeding phase” is essential for long-term success. Principles of a well-balanced diet are implemented to design a long-term weight control program. You will see the registered dietitian every two to four weeks during the beginning of refeeding.


An exercise program will tone muscles and assist with weight reduction and total body fitness. Be sure to obtain physician approval before starting an exercise program. A daily exercise program is encouraged. Your registered dietitian can give some tips on how to get started. An exercise physiologist can set up a more individualized program, if desired.

Estimated costs

Costs will depend upon the length of the program and are subject to change. Check with your health insurance provider regarding coverage before scheduling an appointment. Costs for each visit will include: physician visits (ranging from $235 to $524); registered dietitian visits, based on time ($159 per 45 minutes); and lab fees for blood test (average, $300).

Contact information

There are guidelines regarding participation in this program. If you are interested in the Protein-Sparing Modified Fast, please contact your physician for approval for the program, and then schedule an appointment with a registered dietitian at any of the Cleveland Clinic Family Health Centers, or at the Main Campus (216.444.3046).


This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. For additional health information, please contact the Center for Consumer Health Information at the Cleveland Clinic (216) 444-3771 or toll-free (800) 223-2273 extension 43771. If you prefer, you may visit or This document was last reviewed on: