It's not for everyone, and certainly has its detractors, but I got a lot of success from a "paleo" style approach to my food choices (note I don't say i was on a diet). December last year, I was 102kg (171cm tall), pre diabetes, high cholesterol, hypothyroid, high PSA, despite eating what I thought of as "healthy" foods, rode a bike to work most days and went for 5km jogs twice a week.
Then my doctor told me I was going to get worse and it would be bad. So I read a heap of literature, web sites, blogs, research papers, books, etc and spoke to a few people in the know. A key book I read was "Primal Body, Primal Mind" by Nora Gedgaudas, which really explained to me how my metabolism works and how nutrition works in modern humans. This led me to cut down most sugar and carbs out of my diet (no potatoes, rice, pasta, bread, wheat, flour, grains, legumes, etc) and eat more good fat (avocado, olive oil, coconut, animal fats, etc), moderate protein and heaps of veges. I still drink the same amount of beer (hey - it's not a religion!) and have awesome breakfasts (yesterday I had bacon and eggs, mushrooms, tomato, avocado, all cooked in duck fat!).
Exercise wise, I swapped the long runs for very short bursts of high intensity interval training (3 x 30 secs each on a rowing machine and stationary bike - yes literally only 3 mins of exercise with 1 min break in between bursts) twice a week, with a bit of core strength to fix my back and a few free-weights for bone density. Still ride to work about 3-4 days a week. I stick to all the above most of the week and have the occasional blow-out (gotta love a few Thursday night IPAs, a packet of chips followed by a couple of whiskys :kooi: )
Now I am 76kg, all my health markers have returned to normal, my body fat percentage has gone from 34% to 22% and I feel better, sleep better, look better and have dropped clothes size from XL to M.
Like i said, it won't suit everyone, but once you research the reasons you are unhealthy and understand how your body will respond to certain changes, i found it doesn't take an iron will, just consistency and perseverance.
Cheers - Snow