What causes overweight?

Mike eats all day and still is lean and thin while John is on perpetual dieting but remains obese. This is the commonest enigma faced by all overweight people.The first step in loosing weight is to know what causes it. So what causes overweight?
Here is an incomplete list:-
1. Imbalance between caloric intake and energy expenditure -The commonest cause
2.Hormonal causes –
Associated with poor linear growth
–Hypercortisolism: Cushing syndrome is any type of glucocorticoid excess (endogenous or exogenous); Cushing disease describes pituitary ACTH overproduction
–Hypothyroidism
–Growth hormone deficiency
-Insulinoma
-Hypothalamic obesity
–Tumors (e.g., craniopharyngiomas)
–Following neurosurgery or irradiation
–Head trauma
–Infiltrative/inflammatory
-Genetic syndromes
-Drugs :Chronic glucocorticoids –Neuropsychotropic medications
-Adiposogenital dystrophy syndrome

If you are confused ,just remember this:
THE AMOUNT OF WEIGHT GAIN (OR LOSS)IS EQUIVALENT TO DIFFERENCE BETWEEN CALORIES INTAKE AND CALORIES SPENT