Being vegan in New York City is hardly a challenge. Most restaurants now have vegan-friendly options on their menus, and affordable vegan restaurants are popping up all over the five boroughs. In the three years I've been vegan, I've found that most restaurants and grocery stores have a lot of options readily available — except for fast food.

Taco Bell and White Castle seem to be the only fast-food chains actually working on meeting the growing demand for food that's free from animal products. According to a study by market-research firm GlobalData, the number of Americans who choose to follow a vegan diet has increased from 1% to 6% since 2014.

The population of vegans, vegetarians, and people who are simply trying to eat less meat is growing rapidly, and most fast-food chains are doing little to nothing to make a vegan lifestyle more accessible.

To see which fast-food chains are best prepared to keep up with the growing demand for vegan food, I tried to eat only vegan fast food for five days. My rules were simple: eat only at fast-food chains, and eat three meals a day.

Here's what happened:

I kicked off the week with Fruit & Maple Oatmeal from McDonald's, prepared without cream.

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This is the only vegan-friendly breakfast option at McDonald's, and I made it about three bites into the oatmeal before tossing it out. McDonald's oatmeal has nearly twice as much sugar as a Hershey bar and more than 300 calories per serving. It was sickeningly sweet and packed with sugar — I couldn't stomach it that early in the morning.

For lunch I wanted something lighter, so I headed to Wendy's for a salad. I ordered the Garden Side Salad with no croutons, no cheese, and no dressing. I also ordered a side of apple slices.

The salad was plain and disappointing, and it had to be made twice because the first time it still had cheese on top. Wendy's has tested a black bean burger, but unfortunately, it isn't available anywhere in the Northeast.

I was ravenous by dinner, so I went out of my way to get Taco Bell — a supposed fast-food haven for vegans. I ordered a Seven Layer Burrito with no sour cream or cheese.

Taco Bell has the most vegan options on its menu out of all the popular fast-food chains. It definitely was the most filling thing I ate all day.

After day one, I realised that eating the right amount of nutrients would be nearly impossible unless I wanted to snack on french fries all day. It was an unhealthy start to the week, and I was still hungry at the end of the day.

Day 1 Total:

Calories: 687

Fat: 15.5g

Sodium: 1146mg

Sugar: 36g

Protein: 17g

Avoiding the mistake I made yesterday at McDonald's, I went to Chick-fil-A and ordered a Sunflower Multigrain Bagel with strawberry jam and a fruit cup for breakfast.

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I was limited with my breakfast choices, so in a pinch, this was the best breakfast I could get. It was really plain and didn't come with enough jam for the small bagel, but it tasted fine and was enough to get me through the morning.

By 1:00 p.m., I was too hungry to wait any longer for lunch. I went back to Chick-fil-A to get the Market Salad with no chicken, no cheese, no honey roasted nut blend, and no dressing. I ended up going back for dinner, too, and I got the same salad.

The salad was actually pretty good — it was definitely more flavourful and filling than the Wendy's salad was.

In between lunch and dinner, I felt drained — my bagel, fruit cup, and salad totalled 250 calories and only 6 grams of protein. I already broke the diet to have some fruit and a protein bar, just so I could make it through the afternoon. I couldn't even last two full days on just vegan fast food.

Day 2 Total (not including the snacks I ate between meals):

Calories: 280

Fat: 3g

Sodium: 674mg

Sugar: 18g

Protein: 6g

I ended up going back to Chick-fil-A for breakfast again.

My other options were a side of hash browns, McDonald's oatmeal, or Burger King french toast sticks — which have more sugar than I wanted to eat first thing in the morning. White Castle also has a few breakfast options, but there are no White Castles anywhere along my commute.

I saved the fruit cup from Chick-fil-A for a snack so I wouldn't be so hungry between meals again.

For lunch I ordered the same salad from Chick-fil-A. Again. Taco Bell and White Castle had more options, but they were both far away, and it was raining out, so I went for the most convenient choice. After lunch, I stopped the diet because I felt terrible. I was exhausted, had a headache, couldn't focus on anything, and was desperate for something other than Chick-fil-A.

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Eating at the most convenient restaurants made it even more clear how limited my options were. If Chick-fil-A wasn't around the corner, I would have been stuck with McDonald's oatmeal for breakfast and Wendy's french fries and salads for lunch and dinner. I would have had to go a half hour out of my way to get something more filling, which I didn't have time to do.

Day 3 Total (only including breakfast and lunch):

Calories: 250

Fat: 3g

Sodium: 507mg

Sugar: 12g

Protein: 6g

It was nearly impossible to find a filling vegan meal at a fast-food chain. Almost everything was either so sugary and greasy that I felt sick after eating it, or it was so unsatisfying that it left me feeling hungry immediately after. Even though I struggled to make it through the week, there were definitely some clear winners.

Breakfast: Even though Burger King and McDonald's had french toast sticks and oatmeal, the only place to get a breakfast that didn't taste like pure sugar was Chick-fil-A. It wasn't super satisfying, but it was enough to get me through the morning.

Lunch and Dinner: Taco Bell and White Castle are by far the most accommodating. Most meals at Taco Bell can be made vegan by removing the sour cream and cheese and replacing meat with potatoes. White Castle also has a few vegan sliders on the menu, but unfortunately, these two chains were pretty far out of my way. Chick-fil-A had good salad options, but there was nothing with protein on the vegan menu, which became a huge problem.

Most fast-food chains lack a hearty vegan option on the menu. Sure, I could fill up on fries all day, but it proved impossible for me to actually sustain a diet of just vegan fast food because of how limited the choices were — and how severely those choices lacked any nutritional value.