Obesity is closely related to metabolic diseases and its prevalence is sharply increasing. However, there is no safe and effective treatment for obesity so far, the investigators need a breakthrough idea to curtail the constant threat of obesity. It has been recently demonstrated that emotional tears of women can modify sexual responses, one of basic instincts, in men. As appetite and food intake is another basic instinct, chemosignals from tears and plasma may modify appetite and eating behavior in humans.