Drinking coffee and tea with milk when fasting?

I have been playing with intermittent fasting for a little while and completed 48hour "fasts" a couple of times and felt really great on it mostly. However, my job can be quite physical and I have experienced a couple of times when I have been a bit shakey and weak having not eaten. I just wondered what people thought about drinking tea and coffee (with milk) when I try a longer fast to give me a little boost. Also the instant coffee at work is rubbish so I always drink it with milk. Black coffee is no problem at home.