Can a pediatrics help in gaining weight for age of 21+ patients?

No: I would not expect a pediatrician to be an expert in this area.

No: Pediatricians care for children. See an adult doctor if you are concerned about your weight.

Weight management : Sure. The basic methods are the same no matter the age involved: healthy eating/ weight improvement/ control methods.Pediatricians sometimes interact more with patients and that helps in building confidence in the plans to gain weight if that is the goal here

No too old for PED: Pediatricians do not treat patients over the age of 21.You need to consult an Internist or a Family Physician

Probably not: Pediatrics is generally defined as birth to 21 years old - some will stop at 18 years old. I would contact an Internal Medicine physician to explore issues of nutrition/weight concerns.

Weight gain: You live in California. You should have access to great fresh food. You need foods from all the major food groups. A nutritionist or diction should be able to give you good guidance.

Need internist: Pediatricians generally see patients only until their 21st birthday. After that, it is time to switch to a doctor that specializes in seeing adults.