I ate nothing but vegetarian fast-food for a week - here's the surprising answer to who does it best

Eating nothing but meat-free fast food for five days straight means figuring out which chains have tasty, healthy options - and which restaurants are vegetarian nightmares.

A growing percentage of the American population has already gone vegetarian. While about 3% of the US identifies as vegetarian or vegan, an increasing number of people are cutting meat from their diet; 26% to 41% of Americans report that they cut down on the amount of meat they ate in the past year.

If you're a vegetarian craving fast food, or simply an omnivore who wants more meat-free options, here are what chains you should be checking out, from the worst to the best.

8. Arby's

Unsurprisingly, the chain that promises "we have the meats" doesn't have much for vegetarians. The chain even released an "open letter to vegetarians" last June... to promote its new brown sugar bacon.

"It is understandable that you disapprove of our meat-bravado," the letter reads. "Your voices have been heard. Letters, emails, voicemails, Tweets and Facebook comments - we hear you. We love our meats, but realize they're not for everyone."

The chain's "vegetarian menu hack" is for customers to just to ask for the meat to be removed from sandwiches - all of which are 100% centered on meat. While these sandwiches can actually be tastier than they seem, Arby's is unlikely to ever create a menu item that is intended to appeal to vegetarians.

7. Chick-fil-A

It's in the name: Chick-fil-A is all about chicken. That doesn't mean the chain can't be healthy, but it does mean it doesn't have a ton to offer vegetarian customers.

If you're avoiding meat, you have a couple tasty salad options, plus waffle fries. Still, there isn't much you'll find when it comes to meat-free protein.

6. Five Guys

Five Guys is a burger-and-fries chain at heart. However, it is one of the few fast-food joints to have two satisfying vegetarian sandwiches on the permanent menu: the grilled cheese and the veggie sandwich.

These aren't healthy options by any stretch of the imagination, but they do manage to capture what makes Five Guys great. They're freshly made, cheesy, and you can almost feel them clogging your arteries - just the way Five Guys intended.

5. Pizza Hut

Meat-free pizza is an easy enough order at any pizza chain. In fact, if you're ordering in bulk for a mix of vegetarians and nonvegetarians, pizza is probably going to be the go-to option. My personal pan pizza at Pizza Hut was not great for my digestion, but that doesn't mean the chain should be cut as a valid vegetarian option.

4. McDonald's

All-day breakfast is definitely a bonus for vegetarians - if not vegans, who avoid eggs and cheese. The ability to get an egg McMuffin all day is my new favorite McDonald's menu hack, whether or not I'm on a vegetarian diet. McDonald's has also recently revealed some upgraded salads, like the Southwest Salad, that exceed my expectations for fast-food chains vegetarian options.

3. Subway

Since you build your own sandwich (or salad) at Subway, it's truly as vegetarian as you want it to be. The Veggie Delite is a classic that you can be remixed to suit your tastes - all in all, an unobjectionable option.

2. Dunkin' Donuts

As previously mentioned, all-day breakfast is a boon for vegetarians. I visited Dunkin' for breakfast and dinner, getting a burrito and an eggwhite flatbread, but that barely scratched the surface. You have a long list of egg-based meals, fruits, and, of course, the real reason you visit Dunkin' Donuts: the donuts.

1. Taco Bell

While many casual Taco Bell fans may think of the chain first-and-foremost as greasy, faux-Mexican food, the chain has actually made major strides in providing vegetarian-friendly options.

"Vegetarian has been really big for us recently," because of its relevance to millennials, Taco Bell's dietitian and product developer Missy Nelson told Business Insider.

The chain rolled out a American Vegetarian Association-certified menu in October and benefits from the ease with which customers can substitute beans and rice for meat in most menu offerings. Taco Bell is one of the few chains that can match inexpensive fast-food decadence with vegetarianism - and even adjust meals to be healthy, if you so choose.