Q: how many calories should a 43 year old man eat per day.

A: There is no one answer to this, since it would depend on your weight and physique, physical activity levels, and whether you are trying to lose weight/fat (or possibly build muscle). It can also vary quite a bit depending on your diet -- it's perfectly possible to gain weight on just 2000 daily calories of junk food and lose weight on 2500 daily calories of healthy nutritious meals. For an average man, simply looking to maintain a healthy weight somewhere around 2500 calories daily is a good target.

If you'd like, check out my Fitness Guide and see what it recommends as the diet and total calories depending on your input.