VLCDs do mess up your hormones , when fat is broken down more oestrogen is released and this can mess lots of ladies cycles up , I had the implant the first time I did a VLCD and bled for 5 months continuously .. so it could well just be hormone changes . However VLCDs are also well known for making you super fertile .. so definately worth doing another HPT in a week or so if still no sign .. you can get negative tests if you are drinking a lot of water , so make sure you do it first thing in the morning xx