Protein-sparing Modified Fast Diet : Efficacity, Safety and Clinical Use

Obesity is considered a major public health problem by the World Health Organization (WHO) because of its steady and rapid rise in prevalence in many countries, including Canada. According to data, the prevalence of obesity in Québec was approximately 21.4% in 2004. Studies have shown that obesity and overweight are relatively important risk factors for developing chronic diseases, with serious health effects over the medium- to long-term.

The protein-sparing modified fast (PSMF) diet is part of the therapeutic arsenal available in Québec to anyone having an excess of body weight and seeking intentional weight loss, through commercial manufacturers and in medical clinics. This diet however, was responsible for more than fifty deaths in the 70’s and is still a topic of debate within the specialized scientific community itself.

AETMIS concludes the following:

• The PSMF diet is in no way indicated for people who are not overweight;

• In cases where people are required to lose weight, the leading recommendation by nutrition experts is to prescribe a personalized, balanced moderately low-calorie diet;

• Experts are divided on the place of the PSMF diet as a therapeutic option for obesity. Some believe that the PSMF diet has no place in the current range of dietary interventions. Others, in official position statements, do not exclude its use and consider that it may be used for limited indications.

Examination of the scientific evidence provided in studies on PSMF diets in clinical settings reveals the following: 1) Compliance with this diet is difficult and attrition rates are high; 2) Short-term weight loss is rapid and significant and is accompanied by also short-term changes in clinical and biological parameters suggesting improvements in some associated risks; 3) Its long-term efficacy for weight loss remains less certain, given the conflicting outcomes of the two meta-analyses evaluating this aspect.

Given the lack of long-term efficacy of this diet for real weight loss and its reported dangers, compared with conventional weight-reduction diets, and given the need for medical monitoring, although little documented, combined with a multidisciplinary intervention involving other health professionals, the principle of medical precaution (primum non nocere) is warranted, while that of refraining from the use of this diet must be considered. When used, the PSMF diet should be an integral part of the patient’s general support program conducted by a multidisciplinary team. Given all of these elements, it would be important to draw up a profile of the use of this type of diet in Québec with its achieved outcomes. Lastly, the place of the different professional practitioners in conducting diets geared toward intentional weight loss, including PSMF, will remain difficult to recognize so long as there is reluctance to acknowledge that obesity is a complex chronic disorder requiring consideration of its biological, social and psychological dimensions.