The regulation of energy homeostasis is a complex process influenced by many dietary factors and by the cross-talk between the host and microbiota.

In this thesis, I aimed to investigate the role of certain dietary factors on metabolic regulation using untargeted and targeted metabolomics.

First, I investigated the metabolic fingerprint of protein pre-meals consumed before a high-fat main meal in subjects with metabolic syndrome.

Further, I reviewed the alterations of gut microbiota and the role of short chain fatty acids in early life malnutrition. Lastly, I explored the differences in breastmilk components and their association with fecal short chain fatty acids in relation to infants’ growth