To re-iterate once again:
In the end there's no way to get away from calories in vs calories out. The more sedentary your lifestyle, the less you should eat.
One thing that never seems to get enough mention is sugar. It is everywhere and in almost everything. "Fat free" stuff sometimes has gobs of sugar in it ... that that is what the body loves to convert to fat. Even things like dried mango, cranberries, etc. are often loaded with sugar. It's evil.
Little things can help:
Reduce sugar in your coffee until you don't have any.
Pass on the after dinner mints, the chocolates, etc. etc.
Stop drinking pop (and toxic diet pop).
I was lucky that my metabolism always stayed at about a 15 year old's level. Until I hit 40, then the body wasn't so forgiving.
And one more thing ... sigh ... beer ... limit it ... this was painful for me ...
Drink scotch. :)