We report for the first time that L-arabinose gavage elicited immediate and robust release of hydrogen in mice in a dose-and-time-dependent manner, which can be abolished by antibiotics treatment regardless of diet type; long-term L-arabinose administration effectively reduced body weight gain especially fat weight, improved insulin sensitivity, alleviated liver steatosis, systemic dyslipidemia and inflammation in mice on HFD. Here, INS is linked to fatty liver disease.