High fat diet increases lung metastasis of lipid-rich cancer cells. (A) Histology evaluation of lung tissues in a control mouse, LD mice at 4 and 5 weeks after tumour implantation, and a HD mouse at 4 weeks after tumour implantation. Dashed circles mark the locations of metastasized colonies. (B) Lung metastasis (number of metastasized colonies) as a function of diet. Error bars represent standard deviation across 8 mice analyzed. (C) Lipid-rich cancer cells in the lung tissues of LD (upper panel) and HD (lower panel) mice identified with CARS imaging (grey). Scale bars: 25 μm.