Lose Weight -- in the Drive-Thru?

January is prime time for dieting. Fast food chains are trying to cash on New Year's resolutions by offering an array of reduced calorie options for those trying to lose weight. But buyers beware.

Nutritionists warn that low-calorie doesn't automatically mean it's good for you.

On "The Early Show," CBS News medical correspondent Dr. Jennifer Ashton addressed some of the new options from Taco Bell, Starbucks, and KFC -- and discussed if they can actually be good dietary options.

First, Ashton took on the new Fresco Meals/Drive-Thru Diet line from Taco Bell. These seven new burrito and taco items, Ashton said, range from 150 to 340 calories, with nine grams or less of fat.

"(It's a) good option for anyone looking to reduce their calories," she said.

Starbucks is also introducing new hot sandwiches that are all around 400 calories and range from nine to 18 grams of fat.

"Compared to other panini that can load on six or seven hundred calories, this is a real reduction," Ashton said.

And then there's KFC grilled chicken, KFC is famous for their fried chicken, but to be more health conscious, they brought out grilled chicken options.

The meal featured on "The Early Show" is 400 calories, with 21 grams of fat.

Ashton warned, "There's a lot of salt in all processed foods. That is not so good for your
health."

"Early Show" co-anchor Harry Smith added the fat grams for many of the items are also high.

However, Ashton added, "If you're trying to cut the calories any way you can, these are great options."

Ashton recommended these tips for cutting back when you're on-the-go:

• Hold the cheese and dressings.
• Load up on fruits and vegetables.
• Limit your liquid calories. Water is the best choice.