As the mother of three, ages 20, 14, & 13, a school psychologist, and a wellness consultant, what concerns me is the focus we as a society place upon "normal" size and weight. I would suggest you may want to look at the diet he has begun to crave even at this early age. All the foods you listed are high in carbs and are processed foods. Fruit is great yet, no dairy or protein was listed. Introducing non-processed, whole foods, with yogurt, varieties of cheese, and milk will balance his diet.
My oldest son was always in the top 10-15% of his height and weight. He went through the early teen chubby stage and is now a very health focused eater - no sugars, few carbs, protein, and milk - even as a college student.
My youngest two are adopted from Korea so we expected different growth patterns. Instead, my daughter, the youngest, has always been in the 50-60% in height and weight.
Then there is my 14 year old son. He has been in the 5-10% in height and weight ever since he was a baby. His metabolism is so fast that during the winters, he lives in shorts and t-shirts in the house and is never cold. Fortunately our physician has always focused upon his healthy eating habits and has never focused upon where he was on the growth charts.
As your son's eating habits improve and if you supplement his diet with correct nutritional supplements, you can be assured no matter where he is on the growth chart, he is acquiring the nutrition he needs to grow at his own pace.
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