As always, if you are seriously obese then you should consult a doctor, but the most effective diet schemes are essentially "eat less, exercise more".
A nine year old boy should eat about 2,200 calories
Let the 5 year old lift 100 pound weights and he will lose tons of weight
Yes Extremely Obese Lose Weight
Yes, anybody can. The question is if it's healthy for that 11 year old to lose weight.
To lose weight cut down on calories to 1500 if a boy and 1200 if a girl, not just carbs
a good weight for a 9 year old is 35
A fifteen year old should not try and lose weight unless directed by a doctor. You should wait until you are your maximum height before deciding that you need to lose weight.
an average nine year old boy's weight is about 75 to 90 pounds
10.5kg
yes
Exercise Daily and eat healthily. Speaking to your doctor or a nutritionist would also be a good idea.
An 11 year old should not be trying to lose weight unless it's for medical reasons and a doctor is following the weightloss