When personal-training clients come in for consultations, they cite weight loss as a top priority, says Cassia Denton, a personal training director at Balance Gym in Washington. Comparing calories in and calories out can work, but not when the equivalent to those Boardwalk fries is 14 hours of brisk walking. She tells them that at least 80 percent of weight loss is about nutrition and 20 percent is training. "As the tried and true saying goes, 'bodies are made in the kitchen.' "