Body weight excess, from overweight to overt obesity, is associated with adverse health outcomes. In view of the time-trends of the obesity epidemic and the related cost burden, the search for effective strategies for weight reduction and long-term maintenance of weight loss (WL) is at the top of the agenda of public health systems.

The current first-line strategy includes several treatment options and dietary interventions to be implemented together with an exercise program. Unfortunately, compliance with intervention in the long-term is difficult. It is not infrequent to observe people following one diet after another and experiencing multiple failures which, in turn, lead to higher body weight and adverse consequences on body composition and fat distribution. The higher the number of attempts, the more difficult the adherence to further interventions. In the presence of severe (body mass index >40 kg/m2) or complicated obesity, bariatric surgery could be proposed. This therapeutic option is effective, but is not devoid of complications and may be irreversible. Obesity-related complications, such as diabetes, hypertension or sleep apnoea are likely to occur more frequently with increasing body mass index (BMI) and rapid and considerable WL is mandatory to curtail such risks.

In this scenario, alternative treatment options are warranted. About 40 years ago, after the introduction of protein-sparing modified fasting (PSMF) achieved through the use of oral high-protein foods or liquid formula diets by Blackburn and Bistrian, several studies evaluated its effectiveness and safety. They showed that responsible and supervised very-low calorie diets (VLCDs) could be considered safe and appropriate therapy for obesity.

The purpose of the present study was to investigate the potential role of a 2-week course of enteral treatment with a very low-calorie protein-based formula in the management of severe obesity.

The rationale of this treatment option rests on the following considerations: 1) VLCDs appear to be able to reduce cardiovascular risk rapidly and effectively; 2) VLCDs induce considerable short and long-term WL; 3) optimal compliance with the intervention, as active participation of the patient is not required; 4) continuous administration of the intervention formula by enteral route enables the the maintenance of the body amino acid pool.

Before being proposed for clinical use, a new WL program should be scientifically evaluated. Accordingly, in the present study, attention was focused not only on efficacy in terms of improving the cardiometabolic risk profile, but also on the feasibility and safety of the procedure.

Inclusion Criteria:

• age >=18 years
• severe obesity (body mass index [BMI] >=40 kg/m2)
• history of multiple failures in weight loss programs

Exclusion Criteria:

• age >=70 years
• insulin-dependent diabetes mellitus
• a psychiatric disorder
• previous (<1 year since last chemo- or radiotherapy) neoplastic disease
• current neoplastic disease
• established vascular disease
• recent (6 months), history of diet-induced or unintentional weight loss
• moderate-to-severe heart failure
• arrhythmia
• renal failure (creatinine >1.5 mg/dL)
• current hepatitis
• liver cirrhosis
• any type of gastrointestinal disease
• moderate-severe hypoalbuminemia (<3.0 g/dL)
• altered serum electrolytes
• any other contra-indication to enteral nutrition
• refusal to give written informed consent

Consecutive severly obese patients attending the Clinical Nutrition Unit of our institution for a weight loss program