One way is the damage caused by reactive oxygen species (ROS) that are produced by the burning of blood sugar (Glucose) and oxygen in our cells to produce energy. The free radicals produced by this can cause oxidation damage to surrounding tissues (oxidative stress). The body uses a variety of anti-oxidants (e.g. cholesterol & CoQ10) to control or limit such damage but these can be overwhelmed. The rate of damage may exceed the rate of repair with excessive use of energy from sugar.