only 1lb loss

I was very dissapointed at SW last night as I only lost 1lb making my total loss 3 stone & 9oz. I had been expecting more as I had been on the scales at the gym and they had said 13 stone exactly so I was expecting at large loss. Mandy was still very proud of me as I am the only one who has lost every week, never stayed the same or even put on - so really I should be pleased.

This is one of my smallest losses so far and I am not sure why.

1) my body has got used to the diet and am I starting to plataeu out?
2) Did I eat too much last week - purposly - but did it backfire?
3) Is it that sugary fibre drink loading me with too many calories?
4) I had lots of green days last week - perhaps I had too many carbohydrates?
5) starting to exercise can slow weight loss down

It could be any or all of the above, so what am I going to do about it?

1) not give up - keep going and stay on plan.
2) stop the sugary fibre drink.
3) have lots more red days
4) drink more fluids
5) keep exercising