I think you have to look at likes and dislikes.
Limit the carbs and fats, cook simply, and remember there are few calories in pepper and chilli, herbs and spices.
I got my hubby to eat spinach by wilting it into savory mince.
Just watch out for processed food, it's loaded with sugar and salt.
Introduce new foods alongside of old favourites.
Mash cauliflower into potato: you can serve twice the portion size and keep the carbs low.
Watch out for the fat in cheese.
And who doesn't like fish fingers? if you spray them with olive oil and bake them, they taste as good as fried.
Oven chips will have less fat that deep fried.
Buy an oil sprayer: use it to lubricate pans rather than drenching them in oil.
Don't fry, grill. Don't roast, broil.
Millions of little tricks. Remember, no food is bad food if the portion size is kept right.
Happy cooking.