(CNN) Ordering fast food can be tricky for people who are trying to eat healthfully, but it can be particularly challenging for vegetarians. Menus are often limited in vegetarian staples such as beans, lentils, whole grains and vegetables.
The good news is that more and more restaurants are catering to meatless customers, which now number approximately 8 million adults in the United States, with many more trying to eat less meat in general for health reasons.
"I am seeing more options out there for plant-based eaters who want to grab fast food," said Sharon Palmer, a vegetarian, nutritionist and author of "Plant-Powered for Life."
Vegetarian dining requires some careful planning, however. Here are some tips and strategies for eating well at fast food restaurants if you are a vegetarian or vegan:
Check out menus in advance. Since some chains have more vegetarian options than others, you should go online or try calling a restaurant to see whether there's something you will eat. If the menu seems limited, it may be worth traveling a bit farther if it means you'll get healthier, more appealing meatless options.
Seek out newer fast food chains. Traditional chains offering burgers and fried chicken are sometimes less vegetarian-friendly than newer chains. "Look for plant-based fast food restaurants, such as Veggie Grill, which are on the rise," Palmer said. "Also, look for ethnic fast casual restaurants -- Indian, Vietnamese, Chinese, Ethiopian -- as they have many traditional vegetarian and vegan dishes on the menu that offer delicious options just as quickly as a drive-through."
A website (or app) such as Happy Cow can help you identify vegetarian-friendly restaurants if you are traveling in a city you're not familiar with.
Veggie up. "I like to look for plenty of veggie-rich options -- salads, sandwiches with a side salad, a wrap filled with veggies -- so I am gaining all of those health benefits and the satiety value and lower calorie load of eating more vegetables at a meal," Palmer said.
A good old veggie burger is often an option. "Savvy vegan and vegetarian travelers know that veggie burgers are cropping up in the most unlikely places, like the new veggie sliders at White Castle," said Virginia Messina, a registered dietitian who blogs at The Vegan RD.
Ask about "off-menu" items. Don't assume that if a vegetarian option is out of sight, it's not available. "You'd be surprised how many fast casual restaurants I've been to that offer a veggie burger, but it's not listed on the menu," Palmer said. Additionally, you can try custom-ordering your meal. For example, vegans can ask for burritos, pizza or tacos without cheese and sour cream.
Breakfast, for lunch. Some chains serve breakfast all day long, which means an egg and cheese sandwich from the breakfast menu can be a healthful option, especially if it's paired with a side salad for some veggies.
Pack foods that can balance out the meal. "If you're traveling, you can use fast food restaurants to round out your own picnic fare. I always take whole-grain crackers, peanut butter and mixed nuts on the road with me and then grab a side salad at a fast food restaurant when nothing else is available," Messina said.