Mmmmmm - sugar is 99.9, demerara no different to white - T&L's Golden Syrup is 80.5, T&L's black Treacle is 64, Molasses is 56.
You would need a lot less treacle than you would sugar. BUT it isn't as sweet! 1 tabs is 15mls so that's only 10g CHO in the whole bang shoot.
Worth a try Terry - go for it!