Avocados are "good fat." Beef is "bad fat." Olive oil is "good fat." Cocoa butter is "bad fat."
And when it is translated by the body: a fat is a fat. (Try telling your skinny jeans, "But I ate salmon before that chocolate cake! One of them shouldn't count!")
Turns out, the fat inside of our bodies has a "good" and a "bad" too.
Brown fat is a type of body fat that is full of the darker "energy factories of cells" called mitochondria. Mitochondria feed on calories - lots of them - which are then turned into energy and heat, according to Time. "Baby fat" is actually brown fat, which is why newborns get chilly so quickly and need to be kept wrapped up. As we get older, we get better at regulating our temperature in part because we lose most of the heat-throwing brown fat.
So, how do we turn our white fat into brown fat? Researchers at Yale School of Medicine have figured it out by studying the energy expenditure, eating habits and weight of mice.
Have you ever heard that lowering your calories to too low of a level can stop weight loss? That's because it's true. Fasting can cause the body to shut down and only use energy for vital life functions, like heart and lung functions. Evolutionarily, this makes sense. If your body thinks you're facing famine, it tries to save itself. When the mice needed extra emergency energy, brown fat provided quick bursts of energy.
Associate Professor at Yale, Xiaoyong Yang, said this switch between energy has to do with the relationship between hunger signals and the brain, according to Time.
"We showed that hunger itself is a signal that controls the browning of white fat, so the brain can actually control the browning of white fat," Yang said. "Obese animals, and people, lose the response to hunger. Although there is plenty of food and plenty of energy, the hunger neurons send a false message that the body needs to conserve energy, not burn it."
The trick is to change the hunger signal so it tells the brain to burn fat instead of storing it. Obese mice ate whether they were hungry or not, so the brain and stomach couldn't communicate properly. Signals got ignored.
Plumper animals feel hungry all the time, so the brain shuts down energy expenditure to famine levels. So, you...or rather, the mice... feel hungry constantly and eat continuously while your body thinks you are starving.
Balance, as always, is the answer.
"You don't want to set the body's energy balance to zero," said Yang. "You want to reset it to normal levels."
