Is This Common Ingredient Making You Eat Too Much? A New Study Has The Answer

Why are so many Americans overweight or obese? A new study suggests a common culprit.

Woman Eating Crackers

Over 33 percent of American adults and nearly 20 percent of American children and adolescents are obese. These numbers might be a bit of a surprise, but you've heard about this for years—as a nation, we're getting fatter by the minute. Which means we're putting ourselves at a higher risk of major disease and cutting years (if not decades) off our lifespans.

How did this happen? For one, most Americans don't eat very well. A recent study found that over 50 percent of the average American's calories come from "ultra-processed" foods. Most of us know we should be eating more fruits, veggies and whole foods, but many of us still suck down too many frozen meals and soft drinks. In addition to making poor food choices, we've got a serious problem with portions. Most Americans don't just eat unhealthy foods—they eat way more than the recommended serving size. This combination is a big reason why obesity is on the rise, and a new study sheds light on why we overeat so often.

Entitled "Salt Promotes Passive Overconsumption of Dietary Fat in Humans" and published in The Journal of Nutrition, the study set out "to investigate the effects of both fat and salt on ad libitum food intake." Researchers from Deakin University in Australia recruited 48 healthy participants and fed them four separate lunches over the span of a month. The lunches looked the same—elbow macaroni and tomato sauce—but the researchers altered the amount of salt and fat in each dish. The dishes were either low-fat and low-salt, low-fat and high-salt, high-fat and low-salt, or high-fat and high-salt. Researchers measured how much the participants ate, how satiated they felt after the meal and how much they enjoyed it.

The researchers expected the fat content of the meals to have the biggest impact on overeating, but they found that salt was the real culprit. An increase in salt led people to eat 11 percent more food and calories, and people reported enjoying the food more when it contained a higher amount of salt.

Salting Food

Further, the researchers found that for participants sensitive to the taste of fat, salt inhibited their natural portion control. People who are sensitive to the taste of fat typically eat less of it, so when these participants were served high-fat dishes, researchers expected them to eat less. That was exactly the case with the high-fat, low-salt dish. However, when the same participants were presented with the high-fat, high-salt dish, they ate significantly more. "Salt may override fat-mediated satiation in individuals who are sensitive to the taste of fat," the study's authors wrote.

So the researchers found that salt not only led people to eat more and take in more calories, salt also overrode the satiation factors of other nutrients. It's an interesting finding, made even more interesting when you consider how much salt the average American consumes on a daily basis.

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The American Heart Association recommends limiting daily sodium intake to no more than 1,500 mg—the approximate amount in 2/3 teaspoon of table salt. (Note: Though many equate salt with sodium, sodium is in fact a component of salt. Table salt is about 40 percent sodium; the rest is chloride.) Although athletes who work out at a high intensity for several hours a day can get away with eating more, people who work out only moderately (for an hour or less per day) typically don't sweat enough to warrant a high-sodium diet. According to estimates, the average American consumes 3,400 mg of sodium a day—more than twice the recommended amount. Consuming too much sodium leads to an increased risk of high blood pressure, cardiovascular disease and cancer.

Why do we eat so much sodium? Well, more than 75 percent of the sodium in the average American diet comes from processed foods. So our sodium consumption is probably not due to a heavy hand with the salt shaker as much as the "hidden salt" loaded in the processed foods we purchase. Perhaps the biggest problem is that most Americans have no idea how much salt is in many common processed foods.

Processed Foods

For example, most canned soups contain over 800 mg of sodium per serving. Half a frozen pizza contains roughly 3,000 mg of sodium. A single tablespoon of soy sauce contains 920 mg. A cup of Grape Nuts contains 580 mg. A cup of canned tomato sauce contains 1,000 mg. When you realize how much sodium is in many common packaged foods, it's not hard to see how the average American consumes so much. Then, when you also understand that the high-sodium content of our food leads us to overeat, the reasons behind the increase in obesity  in our society become much clearer.

RELATED: 5 Surprising High-Sodium Foods 

Lowering your sodium consumption starts with cutting down on highly processed foods and replacing them with fresh fruits, vegetables and plant-based options. These foods are healthier to begin with, and their low sodium and high fiber content can help you consume correct portions.

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