Why should you care what color your fat is? You might be sick of thinking about your fat, period. But it’s important to understand fat composition, especially that brown fat has a positive roll in determining your metabolism and keeping you at a comfortable weight. Understanding the process of fat-cell making may help you think more about food choices and actually play a part in determining your brown/white cell make-up.

“When good fat goes bad’ by Barbara Moran (Bostonia, Fall 2014, page 22) explains the function of brown fat and why we want to have more of it. “White fat looks white because it’s full of molecules called lipids, which the body uses for long-term energy storage. Brown fat has lipids, too, but it is constantly using them like fuel to stoke a fire. Brown fat looks brown because it is packed with mitochondria, the tiny cellular powerhouses that keeps us warm and move our muscles. White fat, conversely, is not very metabolically active and has fewer mitochondria.”

It turns out that when normal-weight mice were fed a high-fat, high-sugar diet, their brown fat, an energy burner, began to turn white. Researcher Kenneth Walsh, director of the Boston University School of Medicine’s Whitaker Cardiovascular Institute, came to this conclusion: Feed a normal lab mouse a fast-food diet and the mice will gain weight and become insulin-resistant. This diet “throws them out of whack…and totally confuses their metabolism.” He explains that “Metabolic dysfunction led to the loss of blood vessels, and blood vessel loss impaired brown fat, leading to more metabolic dysfunction. What was really surprising is that the white fat was minimally affected by blood vessel loss, but the brown vat disintegrated.”

Okay, my goal here isn’t to turn you into scientists or depress you. The good news is that inserting a gene which had malfunctioned due to the “high level of toxic fatty acids in the brown fat” had a restorative effect. The “mice’s blood vessels stopped withering, the brown fat perked up and improved its function, and the insulin-resistance improved.”

If you’ve given up on eating better, take heart. Although we can’t be certain that what happens with mice will happen with humans, this study points in an important direction: eating better can make positive changes on a cellular level. Maybe it’s not too late, as you’ve been telling yourself. Maybe you can do something to change your metabolism just by eating more healthfully. Remember that healthy eating leads to increased brown fat which burns more energy. Another reason to eat nutritiously and have hope.