Empathy here. I lived in western (undeveloped) China for 4 years and came back to the States in the summers for a 6 week visit and classes. Now, I hadn't lost weight yet but I know I gained at least a few pounds, maybe 5-10, every summer. They came off quickly when I returned to China and I went back to my "normal" overweight status.
My suggestion to you would be to decide now, before you come to the US, what you will and won't do, and then stick with it. Make a workable plan and commit. For example, what will you do for exercise? How many days per week, for how long? What special "treats" will you allow yourself, and how often? What big food events are important enough to you to splurge on, and what would just be excessive? What foods right now do you really, truly miss? What is worth it and what's not?
Temptation is everywhere in the States, but it's often suggestive temptation. I don't even like Doritos, but when I see a bag in the store I want them. For a long time I would have to go through the internal conversation of reminding myself I don't like them, so it would be silly and wasteful to buy them. Now, I don't need to have that conversation - it's automatic. I use that as an example - what suggestive temptations will you need to plan to avoid when you're in the States?