Reach and maintain ~12% bodyfat with some muscle, without strict monitoring of calorie intake, or giving up entire food groups, or taking PEDs, at 42/43 yrs old*
*Conventional wisdom states that this isn't possible but I have an approach I'm experimenting with, so let's see.
I'm about that now, and I'm 46, turning 47 next month. This is what I did to get to the lowest body fat % I've (probably) ever been:
-upped my cardio. I do at least 1hr of med/high intensity cardio a day. I hate running, and the elliptical fucked my knee a few months back, so I ride the bike. Winter here and cold as fuck, so the stationary bike is my jam right now. (Boring as fuck though)
-cut out most liquid calories. Pretty much only drink coffee and water now. I do enjoy the occasional alcoholic beverage. But pop/soda, all juices etc have been cut right out.
-more protein. I upped my protein intake with shakes and bars. As supplements only, not to replace good whole foods.
-smaller more frequent meals. I eat at least 4~6 times a day.
-lots of vegetables. I try to eat raw vegetables before I eat my main meal. They're (obviously) high in vitamins and minerals, and they're negative calories for the most part. They make you feel fuller, but you take in less calories than the amount of energy required to digest them.
-cut my amount of food I eat. I didn't change the foods I eat, I eat pretty healthy for the most part, but just the size of the portions. Basically 1/2 ~2/3 of what I would have eaten before.
-I upped my weight training. For about a year there I was doing mostly body weight exercises, without a lot of weights. Now I'm doing a 4 day cycle. 3 days of weights, 1 day of just cardio and core. I do core and cardio every day as well.
-a cheat day. I usually have a cheat day once a week. A day to not workout, and/or eat whatever I want that day. Gives you something to look forward to, instead of being so strict that you end up binging.
Anyway, that was how I lost ~25 lbs from the end of July to the end of October, and got down to the lowest body fat % I've ever been.
Good luck man.