This is what happens when you only eat 'healthy' fast food for a week

Although Reilly ended up losing nearly seven pounds, he concluded there wasn't much healthy about the process - and we agree.

Reilly's rules were simple: eat only from McDonald's, Wendy's, Burger King, Taco Bell, Dunkin' Donuts, Subway, and Chick-fil-A for an entire week, and only select things from each restaurant's healthier options menu.

Kevin Reillys Healthy Fast Food Diet:

Reilly ended the week feeling like garbage - the last thing a week of "healthy" eating should feel like. He pointed to a number of problems with these "healthy" options, including that he hardly ever felt full, and that the items were priced higher than many less-healthy menu options.

But the biggest shocker Reilly discovered? The astronomical amount of sodium in these foods, despite the items being low in calories.

Want to learn more? Here's what to know about sodium and the other problems with "healthy" fast food.

What is sodium?

Sodium is a mineral that our cells depend on to function properly. It's a vital part of our health, and the only way to get it into our bodies is to consume it.

Americans get the vast majority of their sodium from sodium chloride - also known as salt. Most processed foods and restaurant foods contain a lot of salt, which acts as a preservative and as a flavor enhancer.

How much sodium should you have in a day?

According to the Centers for Disease Control and Prevention, the average American ingests about 3,400 milligrams of sodium a day. That's over 1,000 milligrams more than the 2,300 milligrams the 2015–2020 Dietary Guidelines for Americans recommends as the maximum amount Americans should take in daily.

When we ingest sodium, our blood retains more water, which causes blood pressure to go up. For people whose blood pressure is already high, too much sodium can cause a serious problem, like increased risk of serious cardiovascular problems.

If you're someone with high blood pressure, then watching your sodium intake is something you should be doing. Harvard's T.H. Chan School of Public Health says that those over 50, African Americans and people with diabetes are also at risk of developing health problems as a result of too much salt in their diet.

The problems with "healthy" fast food

For anyone at risk of developing health problems related to high sodium intake, fast food is not your friend. Reilly mentioned Taco Bell's Fresco menu; the Steak Fresco Burrito Supreme may only have 350 calories and 17 grams of protein, but it also has 1,090 milligrams of sodium.

But high sodium levels aren't the only problems with these "healthy" fast foods.

Big chain restaurant foods are highly processed and secretly loaded with sugar - and we all know the truth about sugar.

Take Burger King's Garden Chicken Salad with Grilled Chicken. It looks healthy enough - 340 calories, 39 grams of protein, 4 grams of sugar. But that's without dressing. Add on Ken's Lite Honey Balsamic Vinaigrette, which sounds healthy, and you've got another 11 grams of sugar, bringing that salad up to 15 grams of added sugar. In a salad.

Besides sodium and sugar, fast foods are typically much more processed and stripped of nutrients, which means you're missing out on a lot of the big benefits that come from whole foods. (Check out more ways your crappy diet is literally killing you.)

So don't be fooled by the "healthy" menu options at these fast food joints - you're better off putting that money towards whole foods at the grocery store. Here are some tips on eating healthy on a budget to get you started.