1. Introduction
obesity, weight loss, metabolic disorders
OBESITY, OBSTRUCTIVE SLEEP APNEA, ARTHROPATHIES, METABOLIC DISORDERS
Background: Protein-sparing modified fast (PSMF) diet is a very-low-carbohydrate ketogenic diet administered to patients with obesity, which preserves lean mass and suppresses appetite as well as continuous enteral feeding. Thus, we aim to evaluate the effect of the PSMF diet administered continuously by nasogastric tube (NGT) or orally. Methods: Patients with a body mass index (BMI) > 34.9 kg/mIn recent decades, worldwide obesity has tripled and is currently reaching epidemic proportions, since in 2016 over 650 million people were affected by obesity [Traditional approaches for managing obesity, such as lifestyle modification with a balanced Mediterranean diet, regular exercise, behavior therapy and drug administration, generally suffer from low long-term compliance [In clinical practice, very-low-carbohydrate ketogenic diets (VLCKDs) are commonly used to achieve rapid weight loss, particularly in patients affected by severe or complicated obesity (i.e., metabolic disorders, obstructive sleep apnea or severe arthropathies) and in patients who need rapid weight loss for severe comorbidities or for scheduled surgery [The protein-sparing modified fast (PSMF) diet is a VLCKD with a high-quality protein content (1.2–1.5 g/kg/day), a carbohydrate amount less than 20–30 g/day and a low-fat intake (about 10–20 g/day); additionally, it requires a significant amount of water (above two liters) as well as vitamin and mineral supplementation [Thus, the continuous enteral nutrition (EN) of a high-protein diet administered through a nasogastric tube (NGT) may be a valid approach for counteracting the catabolism of lean mass [To date, no evidence reports a comparison between a PSMF diet administered continuously via NGT and the equivalent PSMF diet taken orally on anthropometric and body composition data in patients with obesity. Therefore, our study aims to evaluate the effect of a PSMF diet on anthropometric and body composition parameters when supplied continuously by NGT or administered per os. Secondly, we examine the impact of the PSMF diet on blood glucometabolic markers.