Your weight will increase after eating or drinking, but this isn't permanent weight gain. It's related to the actual weight of the food or liquid you just consumed. It's not related to the calories or fat content of the meal itself.
One pound of body fat is equal to 3,500 calories. / 1Kg = 7000 calories. That means you have to create a 3,500-calorie deficit through diet and exercise to lose one pound of body fat. To gain a pound, you'd have to consume 3,500 calories more than your body can use.
