lbs lost but no inches

I've been following an eating plan of cutting out sugar where ever possible and cutting right down on refined carbs (white bread etc). I've managed to lose 5lbs in 3 weeks which is great as only really have a few lbs left to lose and I'm feeling better for it.

After jumping on the scales this morning and jumping off happy I thought I'd grab the tape measure. I haven't lost a single inch or even half an inch from my waist, hips or bust.

Where on earth have those 5lbs gone from? Bit worried that I'm losing muscle, can't think what else it could be. If it was water I should still see some inch loss I would have thought.

I've still been exercising though it's been so hot here the last week or so that I haven't done as much as normal but wouldn't have thought I should be losing muscle that quickly.

I have been eating plenty of food too.

Any ideas anyone????