(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.
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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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
For example, a large slice of Pizza Hut's Thin 'N Crispy Veggie Lovers pizza has 240 calories, 4 grams of saturated fat and 710 milligrams of sodium. But a large slice of the chain's Meat Lovers pan pizza with pepperoni, sausage, ham, bacon, pork and beef has 480 calories, 10 grams of saturated fat and 1,180 milligrams of sodium.
Frozen pizzas can be a convenient dinner, but they too can vary in terms of ingredients and nutritional value, especially with sodium counts, so it's important to read labels carefully (some contain small amounts of trans fats, too). Dairy-free and gluten-free pizzas are available, but as with their traditional counterparts, their healthfulness varies.
When it comes to kids and pizza, one recent study concluded that pizza consumption among children and adolescents was associated with a higher daily calorie intake and higher intakes of saturated fat and sodium. The study also found that pizza eaten as a snack or from fast-food restaurants had the greatest negative impact on calorie intake.
Pizza consumed in schools did not significantly affect children's calorie intake, probably because it may not be that nutritionally different from other school entrees, according to study authors.
If you enjoy pizza on a regular basis, try making it at home using healthier ingredients, such as whole-wheat English muffins, part-skim mozzarella cheese and tomato sauce without added salt. And don't forget to top it with lots of vegetables; the more colorful your pizza, the better!
Lisa Drayer is a nutritionist, author and health journalist.