I find that keeping the meal size down to reasonable portions is a good start. Healthy foods, fruit and veg. No junk food, avoid white bread.
I used to eat porridge for lunch at work with Kiwi and banana or other fruits.
Also found that by really putting the effort in on rides I could burn 1000+ calories on a 25 miler.
Try not to eat treats while sat watching TV, as I find I nibble foods that all add up.
Good luck and stick with it it ain't easy
T