I'd say the thing that interests me most about health and fitness is the positive transformative effect it can have on our lives.
Speaking from personal experience, I was 92kg, borderline diabetic and lacking confidence.
After about 18 months, a strict diet and 3 times a week at the gym I lost 20kg.
As a result I felt much better about myself and radically overhauled my lifestyle.
I think I mentioned these days I can run a 10k a couple of times a week - something that would have literally killed the 92kg me.
In terms of my diet, I use MyFitnessPal to track my food, so these days it's really the "If It Fits Your Macros" diet.
With a couple of cheeky bottles of wine on the side :)
But I've done all kinds of different ones - carb rotation, a bit of paleo, etc., but none of the fasting ones.
I don't think that helps with gym work ;)
In terms of exercise, I'd say that weights are my favourite, but at this time of the year (when the sun's out and everyone wants to look decent in shorts and a vest) I tend to throw in some cardio in the form of 5k or 10k.
I don't mind the HIIT but I tend to save that as a last resort if the fat really isn't shifting by June!