If I eat a very low calorie diet--ALMOST fasting or starvation--of moderate carbs and low-to-no fat but make sure I get all the protein vitamins and other nutrients will my body still burn muscle?

Answer 1

Yes it definitely will. Your body still needs a minimum caloric intake (depending on your BMI, height, weight, activity level) in order to properly function. If you go below it your body triggers a 'starvation mode' and begins conserving fat. Allow this to keep happening and muscle is burned, including your heart and brain which are also muscles. This is why people with eating disorders such as anorexia or bulimia have health complications and can die of cardiac arrest.