Protein bars offer a lot of nutrition in a small package

Wrapped like little stocking stuffers in colorful foil, protein bars beckon from the checkout stands at sports stores and nutrition centers. With flavors such as "S'mores" and "Cookies and Cream Caramel Crisp," and packed with as much as 30 grams of protein, they offer weightlifters and extreme athletes a siren song of rippling muscles in a gooey kid's bar.

"Adding protein is an attempt to aid the person that's trying to manipulate their body composition," says Jeff Kotterman, a licensed sports nutritionist and director of the National Assn. of Sports Nutrition in San Diego. "This [is] for someone who wants to lose body fat and maintain muscle."

Protein bars are also helpful for adventure athletes who spend hours outside in intense activity. "These athletes will tend to get carbed out," says Nancy Clark, a Boston-based sports nutritionist. "If you eat too much carbohydrates, you tend to crave protein."

Clark also recommends protein bars for "extremely lazy vegetarians who don't get enough protein," and college students who don't eat balanced meals. "For them to snack on the protein bar is better than for them to snack on chocolate chip cookies," she says.

The average person needs about 7 grams of protein for every 20 pounds of body weight, which roughly equals 50 to 55 grams of protein for a 150-pound person. For an athlete actively trying to build muscle -- certainly weightlifters would be at the top of the list -- 1 gram of protein per pound of body weight is a very generous protein allowance, Clark says. "More likely, 0.5 to 0.75 grams protein per pound will do the job if you are eating plenty of calories," she says.

The best time to eat a protein or energy bar is generally not during a race or while exercising, Kotterman says. "I recommend bars for serious athletes who need to eat frequently throughout the day and can't get enough calories in or someone who can't eat a lot at once."

Some things to consider when evaluating a protein bar: Look for zero transfat and minimal vitamins. Vitamins, which aren't really necessary, will negatively affect taste.

We asked a panel of tasters to weigh in on four protein bars. Prices will vary by store.

Clif Builder's Calories: 270

Fat: 8 grams (5 grams saturated fat, zero grams transfat)

Protein: 20 grams

Carbohydrates: 30 grams

Price: $1.39

Flavor tested: Cocoa-dipped peanut butter