This goal has the following fine print specified by joi:
My base metabolic rate has been measured at 2062 kcal per day. This is assuming I just lie in bed. For total kcal burned that plus my Apple Watch activity tracker should be reasonably accurate. For total kcal consumed, my Confessional app (confess.joisig.com) is reasonably accurate. Here I track, always day after the fact, the net calories burned minus active kcal.
Initial setting is 1800 kcal net, which is 262 kcal under my base metabolic rate which should mean about 3.8 weeks to lose 1 kg, so a fairly achievable deficit I hope - and then I can develop from there.