Story highlights Pizza offers calcium from cheese and disease-fighting lycopene from tomatoes

Pepperoni, sausage and extra cheese can boost a pizza's saturated fat, sodium and calories

(CNN) Pizza is healthy. And it isn't healthy.

Depending on the type of crust, the amount of cheese and the toppings used, pizza can rank anywhere from nutritionally decent to a diet disaster.

Even healthy pizzas deliver a good amount of sodium from tomato sauce and cheese, so if you are watching your salt intake, you should eat with caution. Of course, the size of the slice and the number of slices you eat count, too.

Pizza pros include the fact that it offers calcium from cheese and disease-fighting lycopene from tomatoes. And pizza crust made with whole-wheat flour (including whole white wheat flour ) is healthier than regular white crust, as it offers whole grains and fiber and is digested more slowly than refined grains.

Photos: 10 foods that are healthy, except when they aren't Dark chocolate is rich in cocoa solids, which contain compounds known as flavonolds. At high levels, cocoa flavanols have been shown to help lower blood pressure and cholesterol, improve cognition and possibly lower the risk of diabetes. But limit your portions to about 1 ounce a day. Hide Caption 1 of 10 Photos: 10 foods that are healthy, except when they aren't When it comes to fat and calories, some cheeses are lighter than others. Experts recommend using it as a flavor enhancer rather than as the focus of a meal. Hide Caption 2 of 10 Photos: 10 foods that are healthy, except when they aren't Granola contains healthy ingredients such as oats, nuts and dried fruit, and it can serve as a tasty topping to yogurt or cereal. But since it can pack up to 600 calories per cup (thanks to sugar and other ingredient treats), it's important to sprinkle, not pour. Hide Caption 3 of 10 Photos: 10 foods that are healthy, except when they aren't Ready-to-eat breakfast cereal can make for a convenient and healthy breakfast, especially if it's made with whole grains, is low in sugar and is served with fresh fruit and low-fat milk. But sugary cereals that lack fiber and protein can cause a blood sugar spike and crash before lunchtime. Hide Caption 4 of 10 Photos: 10 foods that are healthy, except when they aren't Order a California roll, and you'll get heart-healthy monounsaturated fats from avocado and zinc from crab, all for 255 calories. But a crunchy shrimp tempura roll, which is battered and fried and often drizzled with spicy mayo, has about 200 more calories and three times the amount of fat. Hide Caption 5 of 10 Photos: 10 foods that are healthy, except when they aren't Air-popped popcorn is a healthy, whole-grain, antioxidant-rich snack that's low in calories. But movie theater popcorn, which is popped in coconut oil, is a diet disaster, contributing 1,200 calories and about three days worth of saturated fat for a medium bucket -- and that's without the buttery topping. Hide Caption 6 of 10 Photos: 10 foods that are healthy, except when they aren't A Greek yogurt with no added sugar makes for a filling protein- and calcium-rich snack. But sweetened yogurts with flavorings or fruit purees have less protein and are more like dessert, with up to 8 teaspoons of sugar. Hide Caption 7 of 10 Photos: 10 foods that are healthy, except when they aren't Energy bars can be a wise choice for a snack or mini meal if they offer a healthy dose of protein and fiber, and are low in sugars and saturated fat. But when they contain chocolate coatings or sugary syrups, they can pass for protein-fortified candy bars. Hide Caption 8 of 10 Photos: 10 foods that are healthy, except when they aren't A salad made with spinach, light tuna, veggies, feta and yogurt dressing can make for a low-calorie, nutrient-rich lunch. But when your salad contains crispy chicken, bacon, cheddar and ranch dressing, you'd be better off eating a burger. Hide Caption 9 of 10 Photos: 10 foods that are healthy, except when they aren't If you are vegetarian, peanut butter can be a convenient way to add protein and heart-healthy fats to your diet. Just steer clear of flavored peanut butters with sugar and cocoa butter, which can quickly turn your passion for peanut butter into consumption of calorie-rich chocolate. Hide Caption 10 of 10

But what you put on your pizza can significantly impact its nutritional value. Toppings such pepperoni, sausage and extra cheese can boost saturated fat, sodium and calories, while slices made with thinner crusts and topped with veggies tend to have lower calorie, saturated fat and sodium counts.

Read More