What is it and how long does it last around ? Thanks

Not quite sure what you're asking. What do you mean by honeymoon phase, specifically? The period of time when you lose the most? The time when it seems "easy" to make good food choices?

Honeymoon is typically known as the first 6 months after VSG. In this period you tend to lose the fastest, your hunger is the most controlled, exercise has the greatest effect on fat reduction, and the quantity you can eat is much more limited. You can certainly lose after this period, but it is a time when you can drop 50% + of your excess body weight relatively easily compared to later. You still must work during your honeymoon, keep your carbs down and protein up, get your fluids in, and start exercising. The payoff is big, so patients are advised not to waste their honeymoon. This is info from my doctor. Others may have a different definition.