Science Says an Ingredient in French Fries Could Actually Burn Fat

A new study suggests salt has long been misunderstood.

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You know you're not supposed to overdo it on table salt, salty sides like chips and fries, and processed foods because consuming too much sodium can raise your blood pressure and increase your risk of suffering from heart disease or stroke. While these concerns are real, two research papers recently published in The Journal of Clinical Investigation suggest experts have long misunderstood salt's effects on the body and overlooked a potential benefit, which could include burning body fat.

When researchers gave 10 male Russian astronauts on two separate space missions progressively saltier meals, the saltiest ones caused the men to produce the most urine—even though they didn't drink more, as you'd expect. After all, everyone knows that salt makes you thirsty, and it's long been thought people get this desire to drink to help their bodies excreting the excess sodium when they pee.

In a similar experiment involving mice, researchers sussed out why: When the animals ate the saltiest diets, their bodies released more of a hormone called glucocorticoid, which is known to affect the metabolism and immune system. Researchers think this hormone caused the mice to break down fat and muscle to derive water from these tissues, and to flush out excess sodium, which explains the increase in urine output for both the mice and astronauts who were fed the saltiest food.

Because this process requires quite a bit of energy, it's no wonder that eating more salt also stoked the astronauts' appetites. Of course, amping up your food intake can ultimately lead to weight gain—one reason why nobody's saying salt is the key to weight loss. Remember: Salt's newfound fat-burning powers don't strike out decades worth of warnings regarding excess sodium. Overdo it, and your body could produce too much glucocorticoid, which is linked to osteoporosis, muscle loss, Type 2 diabetes, and other metabolic problems, according to Dr. Jens Titze, M.D., corresponding study author, kidney specialist at Vanderbilt University Medical Center, and the Interdisciplinary Center for Clinical Research in Erlangen, Germany, who spoke with The New York Times.

So while you shouldn't go to town with your salt shaker—the CDC still suggests consuming no more than 2,300 mg, or 1 teaspoon of salt per day, and more research is needed to nail down exactly how salt effects the body—this news should make you feel at least a little better when you order your margarita with a salty rim, or if your fries ever need a little extra oomph.

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Elizabeth Narins is a Brooklyn, NY-based writer and a former senior editor at, where she wrote about fitness, health, and more. Follow her at @ejnarins.