Metabolic Impact of Fat Digestion

In this study, the investigators are interested in investigating how the emulsification state and amount of fat in a meal can modify the kinetics of postprandial lipemia and inflammatory outcomes (including endotoxemia) in obese vs lean subjects. 10 lean and 10 obese volunteers will come 3 times (\>3 weeks apart) at the investigation center to receive a standard breakfast containing milk fat (10 g non emulsified, or 40 g non emulsified, or 40 g finely emulsified). 13C triglyceride stable isotopes will allow to follow the metabolic fate of fatty acids and calculate lipid oxidation by breath test. Blood sampling throughout digestion will allow to measure metabolic, lipid and inflammation parameters. Stool will be analysed to determine lipid losses in faeces and to phenotype microbiota.