20lbs in 3 weeks is physically impossible unless you went from a completely dehydrated morning state with no clothes to a post-vacation, post-Chinese food and alcohol drinking binge bloated Sunday night with clothes and shoes on, all while eating an absurd amount of calories for the entire 3 weeks. Sorry, but the math doesn’t work out when a pound of fat takes a 3,600 calorie surplus and the body burns around 2,000/day. That means a pound of fat gained per day, or a 5,600 calorie per day diet assuming no exercise, or 6,000+ calorie per day diet with exercise. Water has zero calories, so that must have been a lot of beer.