Mixed burners use sugar and fat as their sources of fuel, and their lifestyle choices largely determine whether they burn sugar or fat. If they stay up too late, they are tired. If they work too hard, they get sick. If they overindulge in food and drink, they gain weight. Most of the people who come to us are mixed burners and their metabolic tendencies are influenced by their chosen lifestyles. High-carbohydrate diets, stressful sedentary lifestyles, and ...