I am not obese so asking this as a genuine question. Can you still feel the baby moving and kicking due to the extra weight you carry? The reason I ask is that if you can feel the baby moving and kicking so obviously growing, then I wouldn't think you'd need any extra scans than the next person. And even if you really had to hade extra, 4 weekly just seems too many.
The baby kicks from the inside so it has no effect on feeling it with any extra weight you carry. You can still see the baby kicking etc from the outside as well, but everything wobbles for a little longer