This all really depends on how big you got and how you lost weight. Fat cells really don’t go away just shrink down so it’s pretty easy to gain back to your top weight. If you lost a lot of weight rather quickly it will be a lot easier to gain it back rapidly too. It also has a good bit to do with how your diet and stomach capacity is. If you binged a ton and stretched your stomach you’ll be able to eat more obviously. It also depends on your caloric intake as the body can only process so much in a day. You can of course condition your body to absorb more over time but not quickly. So all these factors will affect how you gain back after loosing.
2 months