I can relate. I grew up in a big Italian family, were food was always the central focus of every celebration. That instilled in me the idea that food was indulged in whenever you celebrated (along with copious amounts of wine).
Yet, my family also had some very good attitudes about food. Junk food was never allowed, everything was always cooked from scratch. My little old Italian grandmother, who lived with us, would scoff at the idea of Tomato Sauce from a jar. Nana was a bit ahead of her time and pointing out the crap that made up the bulk of store bought processed foods. "Read the label," she'd say, "you really want to eat that??"
In other words, we ate a lot at times, but everything we ate was made with fresh, real ingredients. We also balanced out our overindulging with modest meals. Since Nana lived with us, most meals were cooked by her, and Nana cooked like an Italian peasant. Meat was a rarity, most meals were vegetarian, although we never thought of them that way. Beans and pasta was a typical meal. When there was meat, it was almost a condiment for week-day meals. If we had any kind of a roast, it would be something along the lines of a leg of lamb at Easter.
Since Nana did the shopping as well, we never had processed snack foods in the house. On occasion we'd get a bag of chips, or candy bar as a treat when we were out, but if we ate cookies (which we actually did quite a bit), it was because we made them. Cookie baking was actually a big family affair prior to any holiday (and we had a lot of them).
That way of cooking and eating led to no one in my family having a weight problem other then my Dad who indulged in junk food like donuts and cake at work. Even his weight problem wasn't significant (and he's still going strong in his mid-80's).
I never weighed more then 98 pounds the whole time I lived at home. I never broke the 100 pound mark until I went away to college, where I experienced the same thing my older sister did. My weight shot up over 20 pounds in one year. The food in the cafeteria was typical American fare and there was too much of it.
I learned to master my eating habits, and exercise more to control my weight in college. But even when I went out on my own, in my own apartment, my diet was still "Americanized." I ate more processed and junk foods.
I was able to maintain my weight through exercise for years, until I hit menopause when I suddenly gained close to 45 pounds in three years. I'm only 5 foot 2 inches, and small boned so this was significant.
I was still exercising (I never stopped), but the only way to lose the weight I found, was to un-Americanize my diet and go back to my food roots. No processed convenience foods and no junk food. The bulk of my diet became raw fruits and vegetables, meat a rarity, and I learned to eat a lot fewer calories.
The bulk of the weight came off.
But I have to get real here, because of my age, keeping it off is a bitch. As you get older, you just can't eat the way you did when you were younger and keep any semblance of a figure.
Yes, losing weight after 45 is a bitch, and the only thing you can do is accept it, eat less and exercise more.