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To reduce your son's life dietary habits should be changed. I think mainly his eating habits and life style is responsible for his overweight
For weight reduction ideal diet plan
involves consuming less calories per day than you burn. The concept is simple, but the implementation of it is a little more complicated.
I advice him to have more fibers and less sugar stuff like sweets and reduce the intake of rice. Regular exercise will be helpful.
Health boosts your ability to metabolize carbs, fats, and protein to reduce food cravings and unhealthy snacking. But i advice you for conservative approach first if it fails then think of these.
Hope i have provided the information you needed.