Hey there!
I have a theory about this... and feel free to take it or leave it!
You have made those men in your life the "caretakers" of your eating habits and weight. When they leave, you are "free" to finally eat what you want, and away you go. When they are coming back, it's like "uh-oh, the police!" and you start into the diet-machine mode.
It's the same kind of pattern that kids get into with parents. Be good when the parents are there, act out when they are not.
So, I'd say the key might be to become the main focus of your own life. Figure out how you want to eat to be most healthy. Become your own caretaker, in other words, and eat to please yourself by eating healthy foods that are good for you. Stop putting it on them, because that's what it amounts to. It's not good always to be looking to externals to control your behavior.
Well, that's my 2 cents. Think about it anyway.
Good luck!
Jay