For a person of average size who looses weight over a reasonable period of time, the natural elasticity of the skin will contract, and no 'baggy' skin will remain.
In the case of a seriously obsese individual, weight loss can be very rapid and dramatic, and in these cases, the skin does not have time to retract, and can leave excess skin which may need removal by surgery at a later date.
It all depends on the size of the individual at the time of weight, loss, and the speed of that weight loss.