Obesity, which results from an imbalance between energy intake and energy expenditure, has become a major health risk factor worldwide, causing numerous and various diseases such as diabetes, hypertension, and cardiovascular diseases. Fucoxanthin, a specific carotenoid in brown algae, has garnered much attention for its anti-obesity and anti-diabetic effects attributable to a unique mechanism. Fucoxanthin induces uncoupling protein 1 (UCP1) expression in white adipose tissue (WAT). That inner membrane mitochondrial protein, UCP1, can dissipate energy through oxidation of fatty acids and heat production. Furthermore, fucoxanthin improves insulin resistance and ameliorates blood glucose levels through down-regulation of adipocytokines related to insulin resistance in WAT and up-regulation of glucose transporter 4 (GLUT4) in skeletal muscle. Algae fucoxanthin is a beneficial compound for the prevention of the metabolic syndrome.