It's possible to lose weight by diet alone. But it's much more effective with exercise. Exercise speeds up the calorie-burning process, increases energy, triggers heart health, boosts mental health and according to a study published in the December 2006 Archives of Internal Medicine, exercise strengthens bones too.

Dieting without exercise can cause bone loss, say researchers at Washington University. Female dieters who lost weight by only cutting calories lost 2.2 percent of bone density in the spine and hips, two areas prone to fractures. Tack on some exercise to that diet plan, and get enough calcium too, and you can lose weight without losing bone.

Seems a simple formula to me. How about you?