Overweight (BMI\>25) and obesity in adults is a global public health concern because weight excess increases the relative risk of disease and mortality 1-4. A range of diseases, notably cardiovascular disease, diabetes and a number of cancers, are related to excess weight 5. Traditional low-calorie diets are frequently ineffective 6. Although a number of pharmacological approaches for treatment of obesity have been investigated, only few are safe and most of them have adverse effects 7,8. Thus, further studies are necessary in order to find natural antiobesity remedies. Gut microbiota composition is thought to influence body weight 9.
As recently demonstrated in our previous study 10, "Acqua Santa di Chianciano"® helps to maintain the body weight and the values of serum lipids stable in subjects under a relatively high-calorie diet. Possible mechanisms may be a) changing the gut microbiota composition and/or b) increasing the concentration and/or the qualitative pattern of serum bile acids with a subsequent increase of the energy expenditure 11. This study wants to assess the effectiveness in losing weight of "Acqua Santa di Chianciano"® in addition to a low-calorie diet and its effects on gut microbiota composition.