Hi Lucy. A loss of 2.4 kg's in the first week is quite nice. Though, it's not an exceptional loss for the first week or two. When you start eating healthier and you start working out and such, the first weight will come off in a larger amount than you have expected. Though, the amount of loss each week will cut back a bit, so it's likely that 2.4 kg's in the next weeks will not happen.
Though, as I said it's quite a nice loss. Congratulations on that and keep it up!
Just a quick question: How tall are you? (Just to reference your weight to your height)