If you're headed out to eat, be prepared to learn a lot about what ends up on your plate -- perhaps more than you ever wanted to.

Eye-popping numbers
Restaurant chains, in compliance with a new law, will soon post nutritional information on their menus. Set to go into effect in 2011, the law will require restaurant chains with 20 or more locations to list calorie contents of items on menus and menu boards. I suspect that shift will be both good and bad for the companies in question.

Here's a sampling of the information you'll soon learn when visiting popular restaurants:

Company

Sample Item on Menu

Calories

Taco Bell, a unit of Yum! Brands (NYSE: YUM)

Chicken Ranch Taco Salad

910

McDonald's (NYSE: MCD)

Chocolate Triple thick Shake, large

1,160

Wendy's (NYSE: WEN)

Baconator Triple

1,360

Olive Garden, a unit of Darden Restaurants (NYSE: DRI)

Chicken and Shrimp Carbonara

1,440

Chili's, a unit of Brinker International (NYSE: EAT)

Brownie Sundae

1,340

Note that, on average, rough guidelines suggest that men should shoot for around 2,700 calories per day, and women 2,000. The idea that one might get three-quarters of a day's calories from a single menu item is hair-raising.

The bad
Having such calorie counts made so public will likely dissuade some customers from ordering the highest-calorie items, which could reduce profits to some degree; the biggest and baddest items frequently cost more. Some customers, seeing just how calorie-laden various chains' offerings are, may stop patronizing them entirely, or visit less often.

In another downside, this added information will likely leave menus and menu boards looking more cluttered and busy. Venues with very customizable offerings will also find it difficult to fully comply. Pizzas, for example, can be configured in myriad ways, and even have-it-your-way burgers can vary significantly in their calorie counts, depending on what ingredients customers choose.

The good
But the new law may be an opportunity for establishments offering healthier fare. KFC has had success with its grilled chicken items, which are expected to bring in about $1 billion in their first year. Starbucks (Nasdaq: SBUX) has also reported hearty sales for an old-fashioned oatmeal breakfast (which sports as little as 140 calories). The folks at Mintel Menu Insights have seen an 8% jump in the number of menu offerings with grilled ingredients at quick-serve chains between 2007 and 2009.

According to the National Restaurant Association, about three-quarters of American adults plan to eat healthier in restaurants this year. Even if all of them don't realize that goal, many will. Restaurants that pick up on that trend could profit.

Don't just look at the big restaurant chains -- small companies, including small dining chains, can be the most impressive stocks.