BMI is very good and if it wasn't for the Diabetes I don't need to lose any weight at all So may be I will the try the 5:2
See how it goes but take it easy and let your body adjust.
I am also finding exercise is very important: walking, press ups, squats etc. Just embarking on resistance training (weights) to build up muscle mass again after weight loss; my twinges say rather too enthusiastically!!