For determining the diet I follow, I need to know what my body needs every day to maintain the current weight. How many calories total, and how much of each macro nutrient?

It all starts at calculating my basal metabolic rate (BMR), and for that I use the formula described by Roza and Shizgal (which is a modern update of the widely used Harris-Benedict formula), for men:

BMR (kcal/day) = ((13.397 * weight in kg) + (4.799 * length in cm) – (5.677 * age in years)) + 88,362

For me, at the moment I write this (47 years and 86 kg) this amounts to:

((13.397 * 86) + (4.799 * 190) – (5.677 * 47)) + 88,362 = approx. 1885 kcal/day

To arrive at my required daily caloric intake, this figure needs to be multiplied by the physical activity level (PAL) factor. At this time, with an injured back and thus little or no activity, this factor is 1.2:

Maintenance level: 1.2 * 1885 = 2262 kcal/day

Now for the macro nutrients:

• Protein: about 2.2 grams per kg body weight (1 gram per lbs): 190 grams (760 kcal)
• Fat: about 30% of the total caloric intake: 678 kcal (75 grams)
• Carbs: what’s left: 2262 – (760 + 678) = 824 kcal (206 grams)

You’ll find that following a diet like this, with a relatively high component of protein, is not too hard if you diligently use tools like a kitchen scale and myfitnesspal.