One Tyler trainer said it's okay to eat a second slice of pie at Thanksgiving, because adding the extra calories won't cause weight gain.

"Thanksgiving food doesn't make you fat," said Colin Davis, who is a personal trainer at 360 Fitness in Tyler, Texas.

Davis said there shouldn't be any guilt for enjoying holiday foods. He said it is unhealthy to look at the need to punish yourself, or increase exercise, to make up for overeating.

One day of indulging won't pack on the pounds, but it's common to feel bloated. That is from an increase in carbohydrates, like dressing, cookies or cranberry sauce.

"Excess carbohydrates makes your body store excess water," Davis said. "They're not going to make you store fat."

Davis said a person can retain anywhere from 3 to 10 pounds in water weight, and hang on to it for several days.

When making a plate, Davis said to eat sensibly. Fill the plate primarily with protein, like turkey, then add the foods that are less nutrient dense.

"Don't freak out. Just get back on track the next day," said Davis. "I'm a sucker for buttermilk pie, so I'll definitely have a slice of that."

Most importantly, Davis said eat the foods you want, stop when you're full and enjoy those around you for whom you're thankful.

"Enjoy your time with your family and friends, because ultimately it's about living a balanced lifestyle," he said. "You've put in 11 months of work already. One day is not going to ruin that."

To get back on track, resume your normal eating habits and exercise routine.

Davis said don't increase your cardio or starve yourself. Just double your water intake for a few days until the scale is back to normal.