The dramatic rise in the prevalence of obesity and diabetes has become a major global public health issue. "Prediabetes" is the term used for individuals whose glucose levels do not meet the criteria for diabetes but are too high to be considered normal. Prediabetes is associated with obesity, especially visceral obesity, is a high risk state for diabetes. Obesity management can delay the progression from prediabetes to type 2 diabetes and is beneficial in the treatment of type 2 diabetes. In the strategy of weight loss there are several dietary approaches available, divided between low calories diet and very low-calorie diets (VLCDs). VLCDs include the very-low-carbohydrate diet (VLCKD) can lead to a state of ketosis. Type 2 diabetes (T2D) has long been identified as an incurable chronic disease; on the contrary, there is evidence that the reversibility of type 2 diabetes is achievable using very low calorie diets or carbohydrate restriction diets. This report provides an update on the scientific evidence relating to highly low-calorie diets and the opinion of the President of the Italian Obesity Network.