This workshop covers the role of FGF21, a liver-derived hormone described as a key metabolic switch for fat loss and energy regulation. It explains how FGF21 influences fat oxidation, insulin sensitivity, appetite control, and energy expenditure, and how resistance to this hormone can impair metabolic health. The session also highlights the interaction between insulin, leptin, adiponectin, and FGF21 in regulating body weight. It also emphasizes that effective fat loss requires structured eating patterns, lifestyle optimization, and metabolic balance rather than calorie restriction alone.