10 simple ideas that have worked for me, so far.
Sleep. I shoot for 8 hours a night. Bed at 10pm, usually rising by 6am. Cool, dark room. Limit screens immediately before going to sleep. If you're on a mac, use Night Mode or f.lux. Occasional meditation. [Lights Out]
Limit Sugar, Eat Plants. I avoid all sugary drinks (and artificial sweeteners), and limit fruit. Ideally, every meal should include some vegetables or greens.
Eat Healthy Fats/Avoid Vegetable Oils. I don't eat vegetable oils. I tend to cook with butter. I get other fats from avocado, eggs and steak. [Peter Attia]
Fast for 16-18 hours per day. Learned from Martin Berkhan. He is the guru of Intermittent Fasting. This approach has given me more focus in the morning, reduced my caloric intake, and made diet adherence much easier. I typically stop eating at 7pm and break the fast at 12pm the next day. During the fasting window, I only have black coffee. [Brad Pilon, Jason Fung]
Lift Heavy Things. Two days a week I lift weights. I stay in the 5-8 rep range and rest as much as I need between sets. One day a week I do an hour of highly variable cardio. There are lots of good programs out there, this is just what I do. [Starting Strength]
(Safe) Starches. I try to eat some starch with every meal (rice or potatoes). In the past, I avoided all carbs and was chronically hungry. Now that hunger is not an issue, I have avoided the binging that plagued my previous very low carb (VLC) approach. Shoot to remain under 150g/day. [Perfect Health Diet]
No Snacking. This one is perhaps more controversial, but I have found that after following a clean diet, I still wanted less body fat. Lowering calories on non-workout days helped with that goal in a big way. One trick is to stop snacking. Eating even a single bite of food starts the craving (ie digestion) process. I find if I stick to 2 meals a day and some dark chocolate (>72%) or a glass of wine at night, I eat less and eat healthier. When I want to get leaner, I eliminate the chocolate and alcohol.
Supplement Wisely. There are too many to consider, but here are some basics.
Vitamin D (2,000 IU) [Council on Vitamin D]
Vitamin C (500mg)
Stress: More and more I have been realizing the power of stress to impact health. I’ve been working to meditate daily, but you can also check out 4-7-8 breathing of the work of Wim Hof if you want other approaches.
I should note one last thing. Be patient. Meaningful change takes time. Trust the process and stick with it. Give these ideas 2-3 months and see what happens. A week or two is not enough to see big differences. Let go of expectation and pressure. Just enjoy the ride. The new you will emerge. Feel free to give it a go and let me know what works (or didn't work) for you as diet is personal.
The above list is currently what I find useful, but diet is an ongoing experiment for me. I will revise this over time as I learn more.