Fucoxanthin is a natural pigment found in microalgae, especially diatoms and Chrysophyta. Recently, it has been shown to have antioxidant, anti-inflammatory, anti-tumor, and anti-obesity activity in humans. Fucoxanthin increases the amount of mitochondrial uncoupling protein 1 (UCP1), a fatty acid-stimulated protein involved in respiration and thermogenesis in WAT of mice and rats.