Is if safe for obese-kids to have very low calorie diet?

Not for young kids: Obese young children who are still growing in height can stay on a low (not extremely low) calorie balanced diet. They should lose enough weight to drop down from the "severely obese" BMI range, into the "obese" range. Then, they can take advantage of their height growth combined with moderate caloric restriction, to gradually drop into the "normal" BMI range over a 1-2 year period. Exercise too!

No: It is very important to work with a nutritionist to determine a good diet for an obese child. Very low calorie diets might lack certain nutrients which are more important for growing adolescents than for adults, whom most diets have been determined for.