Eating sugar compulsively and habitaully like your brother does is a behavioral problem. There is no magical cure for it in the form of medication.
Your brother dietary habits need to be change. I do not know your family's psychological make up, its past and yoru interactions between the memebrs of the family. I do not know dietary habits of other members of the family.
You would need family psychologist.
What I would say is that if you want to eliminate some behaviour, you need to change environmental factors (society, family, natural environment etc.) that are root causes of certain behaviour.
10 spoons of sugar is a lot but not as much considering that 1 can of coke consits over 9 teaspoons of sugar.
I am not sure how old he is (if he is a kid), but most of kids consume dozens of teaspoons of sugar a day from their soft drinks, cereal bars, chocolate bars etc Which is highly dangerous amount that leads to obesity.
thanks a lot for your valueable talk on this