I do cold exposure, minimal duration (5 min/day) high intensity interval training (HIIT), time restricted feeding (tRF), and mild calorie restriction (fewer calories than an average American of my height, age, and gender) with an emphasis on foods that have been shown in reputable studies to boost immune function (mushrooms/alliums/cruciferous veges) and heavy daily consumption of so called "superfoods" (flax seed, chia seed, nuts, beets, greens, berries, beans, turmeric, natto, apples, pomegranates, etc) as well as pre and probiotics. I like to keep my BMI between 21-22 with good muscle tone. I eat a low protein plant based whole food diet.
Muscle mass is an important predictor of longevity (more important than BMI in non-obese people), and there are many studies and meta analysis on ideal BMI, almost none of which point to very low (<20) BMIs as beneficial for longevity. Muscle is also important for "cold exposure" benefits. My LDL has been tested 14% lower than the lowest reading from the "Fontana CR group" and matches that of native hunter gatherers. My BMI is on the high end of the Fontana CR group, and blood pressure on the low end range of the Fontana CR group:
My fasting glucose has been measured 27% lower than the lowest reading from the Fontana CR group (only due to cold exposure practice, which I now feel is essential for maximum longevity). It has gotten so low that I bought a second, different brand of meter just to confirm the readings:
Other measures that I attribute to a healthy diet and lifestyle including cold exposure include: My heart rate variability exceeds that of many children and elite olympians, not to mention the Fontana CR group. My sleep is profoundly deep and restorative.
I believe content of diet is extremely important for optimizing biomarkers of health. I eat a plant based whole food diet with 30-35% of calories from fat (plant based, non-saturated fat) and only around 10% from protein (again plant based protein which is important for keeping IGF-1 low). Ground flax seed, chia seed, turmeric + pepper, inulin FOS, and mixed nuts + walnuts are all essential daily items for me in addition to a wide variety of cruciferous veges, alliums, mushrooms, beets, beans, black rice, purple & orange potatoes, and berries of all types. I do simple/minimal HIIT exercise daily for muscle maintenance and cardio clearing. The supplements I take are Inulin/FOS, Creatine, B12, D, K2, iodine, and vegan DHA. No protein supplements are needed.
At one point in time I was tracking every calorie, did this for a year. The analysis was helpful initially, but then I found it to be a worthless waste of time. I picked a BMI that I felt was optimal for health and longevity based on published research (for me, I determined around 21 was ideal, but may increase that as I age). I weigh myself every morning, if I'm over my target, I eat a little less that day, if I'm under, I eat a little more, that's all there is to it. Cold exposure (CE) practice requires consuming extra calories, but you don't have to think too hard about it, your body tells you when you need more calories, but if you aren't listening, the scale will tell you ;) Body weight exercises, especially pull ups and hanging crunches are excellent for maintaining muscle mass, running up and down stairs with a 40 lb. weight vest is also one of my favorites. This is what I look like after a 5 minute workout (empty stomach):
(but I pretty much ONLY look like this after a workout, on an empty stomach, and flexing, which means almost never, haha, the rest of the time I look pretty "normal" for a lean, healthy person, and look like I have a beer gut after eating a large, high fiber, plant based meal - which I do every day).