Cant - try taking a high strength vitamin C tablet - a 1000mg one (most of the soluble/fizzy ones are high strength - but just check the ingredients).
Or, a strong, black coffee.
Lots of water - try drinking hot water.
Some exercise - a brisk walk or a run.
Lots of fat.
Are you actually eating enough green veg? You should be getting most of your carbs in the form of veg/salad, to help with this issue.
If all else fails, I can 'recommend' Thornton's sugar-free (diabetic) toffees and chocolate bars. But be warned - if you buy a bag of toffee, don't eat them all in one go! (Been there, got the t-shirt - as well as a pulled muscle from the diarrhoea that followed
)