Eat one less cookie a day.

17. Eat one less cookie a day. Or consume one less can of regular soda, or one less glass of orange juice, or three fewer bites of a fast-food hamburger. Doing any of these saves you about 100 calories a day, according to weight-loss researcher James O. Hill, Ph.D., of the University of Colorado. And that alone is enough to prevent you from gaining the 1.8 to 2 pounds most people pack on each year.