You consume extra food inspite of getting enough energy. The taste of the food compels you to eat more.
The problem isn’t apparent. You might not gain weight because you are in college and you do a lot of walking, exercise and fun activities.
But the habit stays so when you get a job, your lifestyle changes. And thus you start to gain weight.
The idea is that when the situation changes, reevaluate your lifestyle.
When you get a kid, you need to change how you see your relationship. When you get new job, consider changing your lifestyle with new timings.
So the crux is be supple. Because things will change. You must too.