I fast for 24 hours every week so autophagy can set in, my nutritionist who put me onto it said I could drink black tea or black coffee and also suggested keeping a jug of water in the fridge filled to the brim with cucumber slices in. I drank the latter in the summer and as I don't like black tea, black coffee at this time of year. Every other day of the week I have two eating windows the first from 1200 to 1300 and last 1700 to 1800. Outside of those hours I eat nothing but drink coffee with cream as there is less sugar in double cream than in semi skimmed milk.