It has been well documented that people typically underestimate calories in foods by as much as 45 percent. Even registered dietitians underestimate the calories in foods by as much as 16 percent. I'm not suggesting that you start counting the calories in everything you eat; however, it would be helpful to at least get an idea of the cost of what you consume. The following sampling of single food items is intended to give you a flavor of what that food really costs in terms of calories along with a few nutritional tidbits.

ONE PISTACHIO NUT VS. ONE STACY'S PITA CHIP

The pistachio is certainly smaller, but it is a nutrient powerhouse at 3 calories per nut. In addition to providing dense levels of seven essential nutrients (thiamin, vitamin B6, copper, manganese, potassium, phosphorus and magnesium), pistachios are a good source of fiber and the only nuts with high levels of lutein and zeaxanthin, antioxidants that are good for eye and heart health. Pistachios can help lower bad cholesterol and increase good cholesterol levels. And while I like the taste of a nice Stacy's Pita Chip, it's not exactly healthy. In fact, these chips have a bit of an unearned health halo. I often see people downing them as if they were a health food, but they have 9.3 calories per chip and are made with flour, water, sugar and oil. Yes, a Stacy's chip has fewer calories than a regular chip, but it's still a chip.

ONE CHEERIO VS. ONE CHOCOLATE CHIP

A single Cheerio has a bit less than a third of a calorie, and there are about 330 Cheerios in a cup ... not too bad. Cheerios do start out strong with whole-grain oats, but they weaken when you consider the added sugar and other less-than-healthy ingredients they contain. That said, they're still one of the better cereals out there.

The term "chocolate chip" is pretty generic. You can have dark chocolate chips or milk chocolate chips, and the dark chips can vary in cocoa content. On average a chocolate chip has between 3.5 and 5 calories. Ghirardelli 60 percent Cacao Bittersweet Chocolate Chips have about 5 calories per chip but are clearly a better choice than milk chocolate chips. Dark chocolate contains a particular subclass of antioxidants called flavonoids, which have been prove to keep blood healthy and prevent cell damage and inflammation. A diet supplemented with the kinds of antioxidants found in chocolate or red wine can slow oxidation of LDL ("bad" cholesterol) and increase the level of HDL ("good" cholesterol).

ONE BLUEBERRY VS. ONE REESE'S PIECE

Of course, the blueberry is significantly healthier and loaded with nutrients. Blueberries protect against heart disease, weak eyesight, cancer and aging. Anthocyanin, the antioxidant that gives blueberries their deep blue pigment, helps to make them one of the healthiest food choices in the fight against aging. And what a calorie bargain at only 3/4 of a calorie for one blueberry! As for the Reese's Pieces: Sugar and partially hydrogenated oils are the main ingredients. They also contain artificial coloring, and they have 4 calories per piece.

ONE MARASCHINO CHERRY VS. ONE MARSHMALLOW

The maraschino cherry actually has a long history. The U.S. Food and Drug Administration had to define it in the early 1900s because of all the imitations. For a cherry to be a true maraschino, it had to be soaked or preserved in maraschino, "a liqueur or cordial prepared by process of fermentation and distillation from the marasca cherry, a small variety of the European wild cherry indigenous to the Dalmatian Mountains." Then, in the late 1930s, the FDA declared that to be called a maraschino cherry it simply had to be dyed red, "impregnated with sugar," and packed in a sugar syrup flavored with an almond-like taste. The maraschino cherry has 8 to 10 calories per cherry, but the calories are just the beginning. It's made with sugar, high-fructose corn syrup and various chemicals, including red dyes 3 and 40 (food colorings that have been linked to hyperactivity and behavioral problems in children). So the "cherry on top" is not really the tops.

Marshmallows, however, are not much better. They're made with corn syrup, sugar, modified cornstarch, dextrose (all of which are sugars, by the way) and gelatin. And get this — they're 25 calories each — wow!