Nutrition Tips

The Surprising Link Between Salt and Weight Gain

The Surprising Link Between Salt and Weight Gain

People who eat more salt tend to weigh more. But maybe not for the reasons you think.

Eating a lot of salt can cause your body to retain more water, which can show up on the scale as extra pounds. But we’re not just talking about water weight here. High salt diets appear to be linked to higher body fat—in particular, the kind of fat that accumulates around your middle.

There are a few obvious explanations for this. First, just think about what kinds of foods tend to be higher in salt: snacks, chips, fast food, fried foods, processed foods, and restaurant meals. It might also surprise you to know that bread is one of the primary sources of sodium in the Western diet.

All of these high-sodium foods are also relatively high in calories. Not only that, they are notoriously easy to overeat. So, if your diet contains a lot of snacks, chips, bread, fried foods, and restaurant meals, you’re not only going to be consuming a lot of salt, but probably also a lot more calories. That could certainly explain the link between sodium and weight.

There are some other possible explanations. Taking in more sodium can also increase your appetite, leading you to eat more. Salty foods can also make you thirsty, which could increase your intake of caloric beverages like soda or beer. (That’s certainly what they’re hoping when they put those bowls of salty snacks out in bars!)

If high-sodium diets are more likely to be high-calorie diets, then it’s not exactly a mystery why people who eat more salt also weigh more. But then a 2015 study found that higher sodium intake was linked to higher body weight and larger waist circumference—even when calorie intake was not higher.

That’s a little harder to explain. But some new research suggests that the link between sodium and obesity could also involve the microbiome. (Lately, it seems as if all roads lead to the microbiome, doesn’t it?)

Dominick Müller’s research group at the Max Dellbrück Center for Molecular Medicine in Berlin just released data from a new study showing that high-sodium diets may kill off the beneficial lactobacillus bacteria in our guts—which may set us up for weight gain. Conversely, moderating our sodium intake may help us maintain healthier gut flora, which is associated with healthier body weight. Who saw that coming?

High-sodium diets also tend to increase blood pressure, of course. We’ve always assumed that this has to do with how sodium intake affects water retention and blood volume. But could the change in gut bacteria play a role? Potentially, yes.

Could it be that a probiotic supplement could one day be an effective treatment for high blood pressure in humans? Time will tell.

Müller’s group found that in mice, anyway, administering a probiotic along with a high-sodium diet not only restored the mice’s gut flora, it also decreased their blood pressure. They are currently awaiting approval for a study to test this in humans. But the preliminary findings certainly suggest that the effect of salt on blood pressure and its effect on gut bacteria are not unrelated.

Perhaps blood pressure is yet another in the growing list of bodily functions that are influenced by the bacteria in our intestines, along with brain chemistry, cholesterol levels, immune function, digestion, hormones, blood sugar metabolism, and weight management. And to think that only a few decades ago, we didn’t even suspect that all those little beasties were in there, much less that they were pretty much running the show!

Could it be that a probiotic supplement could one day be an effective treatment for high blood pressure in humans? Time will tell. In the meantime, simply avoiding excessive sodium consumption could help preserve a healthier microbiome. And to the extent that limiting sodium also means limiting our consumption of highly-processed, high-calorie junk food, so much the better!

There’s no need to ban the salt-shaker entirely. If you simply focus on eating more whole and minimally-processed foods, the sodium will probably take care of itself, even if you salt your food to taste. As it happens, that same strategy of eating more whole and minimally-processed foods is also a good way to lower your blood pressure and manage your weight. Your gut bacteria may be the link that ties all of this together.

This post first appeared on

Image of hand pinching salt © Shutterstock