Hi Tamsyn,
No need for embarrassment, as plenty of us have plenty to lose!
I was also over the 100kg mark and have been following the 5:2 Med style and losing fairly steadily. I am 26 kg down with another 17.5 kg to go. But I just want to get rid of those kilos now so I have resolved to do the BSD eight week diet and this is also my first day on that.
With the chicken breasts here in NZ some are monstrous, so I cut those in half and freeze for later use. I think somewhere on this forum I may have see a comment about people not needing to eat more than 100g of meat every few days. Someone can correct me on that if I remember it wrongly.
With the variation in calories, it may be the marbling of fat in the meat varies or the cut may have more, such as a porterhouse vs fillet steak, so use them as a guide and just try to stay close to the 800 where possible.