Calories in = calories on - assuming you haven't got some physiological issue. Messing round with fat pets confirms this. My wife and I both lost weight by the following - a variation on what others have said:
Cereal breakfast (porridge or weetabix) most days, cooked treat on Sunday
Something sensible for dinner
Normal meal for tea
No booze on school nights, no cakes or snacks (unless it's a "special"). A telling thing was the change for my wife from taking salad to taking a chorizo/chick pea/spud mix with grains as her lunch. On the salad, she was more likely to snack.
My wife has also done pilates sessions every night for 2 years now, in total she's lost 10kg. I lost less - about 5, but it's crept up again as I've moved to a desk job, so less time in the garden/stalking and more chance for snacks. The pilates worked well for core, I found it easier to retain balance with pack and rifle when walkign through clearfell.