Study: PSMF Diet Shown To Provide Long-term Weight Loss

For several years, Cleveland Clinic has been offering the protein-sparing modified fast (PSMF) as part of a medically-supervised and structured weight loss program. This diet is a rigorous way of helping patients to rapidly lose a large amount of weight. The PSMF is a ketogenic diet, meaning it is high in fat and adequate-protein and low in carbohydrates, thus forcing the body to burn fats rather than carbohydrates.

A recently conducted a study was designed to determine if the PSMF can produce positive long-term weight loss. The study looked at patients with and without diabetes, and compared results with a conventional diet. It was done by the Cleveland Clinic departments of Endocrinology and Quantitative Health Sciences, along with researchers at Case Western Reserve University.

“Our results show that the PSMF diet can be used as an effective and safe method in the outpatient setting for long-term weight loss,” says researcher Sangeeta Kashyap, MD, of Cleveland Clinic’s Department of Endocrinology.

The objective was to look at the efficacy of weight loss maintenance on this diet over the long-term.

This review had never been done before. Over two years, the team followed 175 adults, with 127 adults on the PSMF diet and 48 adults on a conventional diet. It looked back at Cleveland Clinic patients from 1995 to 2014 who were part of the PSMF program or took part in standard low-calorie diet counseling. Subjects had a BMI of greater than or equal to 27 and selected a weight loss protocol; they were recorded at 6, 12 and 24 months following the end of the diet.

After two years, it was discovered that the weight loss from baseline was greater for the PSMF group compared to the conventional diet group (-12.4% vs. -2.6%, p<0.001). This type of diet has also shown to improve hyperglycemia and insulin sensitivity in patients with type 2 diabetes. But there had not been much known about whether a very low calorie diet could lead to sustainable weight loss.

The strength of the study was that it focused on the long-term weight outcomes in those who had an initial short-term weight loss followed by ongoing nutritional and behavioral counseling. However, the comparative analyses must be interpreted with caution due to small group numbers and the fact that it was a retrospective analysis.

It was noted that PSMF subjects who received instructions from the dietitian on gradual and reduced carbohydrate refeeding after ketosis saw significant weight loss at end of diet compared to those who did not receive the instruction. The subjects were instructed to limit carbohydrate intake to approximately 90 grams each day for eight weeks. After that an intake of about 130 grams was recommended to keep the weight off.

“We found that greater initial weight loss and long-term weight loss was associated with carbohydrate refeeding counseling,” says Dr. Kashyap. “This showed us how important the follow-up with limited carbohydrate refeeding is for maintaining weight loss.”

The research team recommends that further study concentrate on expansion of the two intervention groups and characterization of the BMI and PSMF refeeding subgroups, as well as analysis of cardiovascular and metabolic benefits, with a goal of understanding optimal duration and delivery of refeeding.

The team also noted that successful maintenance of weight loss requires long-term management from a team of primary care providers and physician specialists, including surgeons, dietitians and counselors. The study conclusion stated: “PSMF results in effective short-term weight loss of more than 5 percent from baseline weight. Follow-up for limited carbohydrate refeeding instruction is important for weight loss maintenance up to two years after initial weight loss.”

Details of the study were published by the American Association of Clinical Endocrinologists in Endocrine Practice.

Dr. Kashyap is Associate Professor of Medicine at Cleveland Clinic Lerner College of Medicine and Staff Physician in the Department of Endocrinology at Cleveland Clinic.