*How can you say it sounds like an eating disorder, because he's eating less than when he was overweight? confused
Also, the OP says "He struggles to eat a big dinner". Well so do many people and given that the OP and her husband are both overweight, what exactly is their idea of a big dinner? Possibly far too much for a 13yr old child. Also, he's 'only eating half a bowl of cereal', but again, how big are the OP's bowls?
WRT breakfast, previously he was eating up to 4 crepes with Nutella and now he isn't. Do you not think that's a good thing, given that the OP was considering buying him plus size trousers even though in her OP, she describes him as 'solid' rather than fat?
She's said he's now on the 'lean side of slender' and the trousers she bought him last December are too big...the trousers the OP described as previously being too tight.
None of what the OP describes here points (imo) to an eating disorder, but so many things in her posts point to her having quite a skewed idea about portion size for kids and healthy eating.
Which is evident in the fact that both she and her husband are overweight (possible medical conditions that cause weight gain aside).*
I agree with all the above.
The OP probably has skewed ideas of portion size, she has said herself that he is not skinny, but now a normal weight.
If he gets to being too skinny then this would be an issue. To me the amount of food he is eating sounds fine, nearly 2 pieces of toast and a glass of milk, would suit most adults for breakfast, let alone a 13 year old.