Fat Feels Stress, Too—And That May Make You Fatter

Body fat gets a bad rap—and in large quantities, rightfully so, because it's associated with a wide array of negative health outcomes. But it might just be smarter than you think. A new study published in the journal Psychoneuroendocrinology suggests your body takes cues that it’s stressed not only from the brain, as previously thought, but from fat itself.

“Basically, what research shows is, you have a signal coming from the stress hormones—cortisol, for example—that circulate through and hits various depots in the body, including fat,” James Herman, a co-author of the study and a professor of psychiatry and behavioral neuroscience at the University of Cincinnati College of Medicine, tells mental_floss. “The signal tells these depots to mobilize energy. In the fat, stress hormones called glucocorticoids stimulate lipid [fat] breakdown. Those lipids, or free fatty acids, circulate as a source of energy.”

As those fatty acids break down and circulate, they send a signal to the brain to release stress hormones—essentially telling the body that it should conserve fat.

“It’s a negative feedback loop,” Herman says. “Cortisol causes lipolysis to release energy but stimulates the growth of fat cells, replenishing it. It’s a double-edged sword.”

Cortisol targets visceral fat, he says—the kind that's implicated in cardiovascular disease and metabolic syndrome. Understanding this process could be key to prevention of obesity and metabolic illnesses.

The researchers still don’t know exactly where in the fat the signals are coming from; locating that source is the next goal of research. “It sounds simple,” Herman says, “but the problem when you’re dealing with lipids/fats is that a lot of substances are released—oleic acid, palmitic acid, and many more. It’s entirely possible that the glucocorticoid signal in the fat is being mediated by nerves that are in fat paths that could bring signals back into the brain.”

The research, which has only been conducted in mice so far, has the potential for significant treatments down the road. Currently, the main way to modulate stress in the brain is through psychotropic drugs, such as antidepressants and anti-anxiety medications, which also come with significant side effects. “If you can develop a target that reduces stress by manipulation of peripheral factors, it might be able to take the edge off the impact of stress,” Herman says.

Reducing stress might take the form of a new pharmaceutical that “interacts with free fatty acid signaling,” he says. It could also work through dietary manipulation. “One of the things we know is that stress profoundly effects food intake. When you’re stressed you tend to eat more high fat and high sucrose foods—comfort food, in essence, which co-opts a lot of these pathways and provides stress buffering to the brain.”

The best outcome of this research, which Herman feels optimistic about, would be to learn how to stimulate the same pathways when your stress meter runs high so you don't turn to Krispy Kremes or a block of cheese to achieve the same comforting effect.