Two major factors push the body into an unhealthy sugar-burning mode of energy production: 1) stress and 2) eating foods that are burned as sugar. Many factors, some obvious and some hidden, create a stress response. Usually diet is the biggest factor. Sugar and starch push your energy metabolism in the direction of sugar-burning, as does protein that is in excess of your daily needs. Healthy omega-3 fatty acids push your energy metabolism in the direction of burning fat, and unhealthy oils block your ability to burn fat.