Was i wrong to call my 10 year old chubby? I felt like he needed tough love?

My 10 year old son is 7stone and quite tall. His diet is not great at all, he wont eat meat and very very little veg. I cant force feed him only try and get him to eat nutritious foods. But as i work full time its not always easy to watch what he eats and his granny kinda lets him get away with rubbish food so long as he eats. Well Sunday it came to a halt, at 1pm i asked him if he ate breadfast, he didn’t i got quite angry and told him you will turn out very chubby if you don’t start eating right, people will say your getting fat. I know my words were cruel and upset him but i thought all my coaxing and gentle words are’nt sinking in so time for tough love. My main reason for this is because when my mother went back to work full time my younger brother fended for himself more or less, he used to eat fries, chips etc etc he is now very over weight and i don’t want to turn a blind eye like my mother did, its only now she realises how over weight he is. So i thought if i was a little tough on my son it would shake him into eating healthier. Last night he was asking me about good foods he could eat and we sat down and made a list of the foods that are healthy and he likes and im doing a little food shop for him every week so i think he is taking me seriously now but i don’t want to give him a complex and cause some sort of eating disorder. Was i right or wrong or how would you have approached the situation. I feel bad for not being there but i have to work but i am going to help him make better choices during the days when Gran is minding him and make him more aware of healthy eating.