How Salty Foods Affect Hunger and Weight Loss

 

Most of the warnings we hear about reducing the amount of salt in our diets have to do with reducing the risks related to high blood pressure.  But a new study suggests another reason that some people may want to curtail their sodium intake: Eating salty foods may make you hungrier.

I’ve always suspected on an intuitive level that salty foods might lead you to eat more than you otherwise would–simply because they can be tasty.

For example, I am likely to eat more salted nuts than unsalted nuts.  Even though I enjoy the flavor of unsalted nuts, somehow salted nuts are more compelling. Instead of having a handful and feeling satisfied, as I might with unsalted almonds or cashews, I just want to keep eating salted nuts.

In fact, one of the things that I suggest for people who find it difficult to observe portion control when eating nuts is to switch to the unsalted variety.

But this recent study found something even more interesting, and way more complicated.


A Salty Diet May Increase Appetite

This study was done on a small group of Russian cosmonauts who were living in a simulated space capsule as training for a long mission. Over the course of the study, the researchers changed up the amount of salt in the cosmonauts’ diets, ranging from a low sodium diet of around 2300 mg per day, to a more typical intake of 3,500 mg per day, up to a peak of 4800 mg of sodium a day.  Although the salt varied, the calorie levels remained the same. And yet, as the researchers increased the amount of salt on the food, the subjects reported being hungrier.

A parallel study done by the same researchers in mice found that higher sodium diets caused the mice to eat a lot more food.

The other weird thing that the researchers noticed—in both the men and the mice—was that as their salt intake increased, their urine output increased—despite the fact that they were drinking less water.

How the Body Gets Rid of Salt

Increasing urine production is one way the body has of getting extra sodium out of the body.  For the last 50 years at least, we’ve been told that when people eat more salt it makes them thirsty, causing them to increase their fluid intake. That extra fluid increases urine output, which helps flush the excess sodium out of the body.

That’s the story anyway. And that’s the logic behind that bowl of salty pretzels on the bar. It’s there to make you thirsty so you order more drinks. Well, barkeeps, you may want to reevaluate your strategy.

In these studies, eating more salt didn’t make the subjects thirstier; over the long run, it made them less thirsty. And yet despite drinking less water, they were producing more urine. So, where was all that extra fluid coming from if they weren’t drinking it?


You Won’t Believe This

It turns out that we humans have more in common with camels than you may have thought. Like camels, we have the ability to produce water by breaking down our own fat and muscle tissue.

And that appears to be what happens when you eat a lot of salt.  Levels of glucocorticoid hormone in your body go up, and this triggers the breakdown of fat and muscle tissues, which releases water, which helps flush the excess sodium out of your body. All of this fancy metabolic activity burns extra energy and calories, which makes you hungry. Who knew?

Will Eating More Salt Help you Lose Weight?

Now, you may have zeroed in on the fact that eating more salt causes your body to break down fat and burn extra calories. Perhaps you’re wondering why a high-sodium diet wouldn’t be a good way to lose weight?

For one thing, the increase in your appetite could easily lead you to consume a lot more calories than whatever extra calories your body is burning to deal with the salt.  But there are a lot of other reasons that this is a bad weight control strategy.

The glucocorticoid hormones cause your body to break down muscle as well as fat, and that is NOT the kind of weight you want to be losing. High levels of these hormones are also linked to an increased risk of osteoporosis and Type 2 diabetes.


The Bottom Line

This study has thrown everything we thought we knew about how our bodies regulate sodium and fluid into a bit of a blender. But in a way, it raises more questions than it answers. One of the things that I’d like to see researchers look at next is whether increasing your fluid intake (whether you’re thirsty or not) helps prevent the sodium-triggered bump in hormones that causes your body to break down its own tissue.

The study also produced some unexpected findings relating to salt, metabolism, and appetite. But contrary to some of the headlines you may have seen, it doesn’t show that eating more salt will help you lose weight.

To the contrary, eating more salt may increase your appetite. And salty foods are often high in calories as well. Either way, eating too much salt could easily lead you to take in more calories than you need.


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