Carbs are the enemy. Past teenage years, heavy intake of carbs leads to problems like low testosterone, increased body fat, and even more dangerous complications like insulin resistance.
High protein diets are the best antidote for aging metabolism. Unfortunately, the US market has been flooded with a dangerous predominance of protein sourced from soy. Soy protein is frankly crap. Like high fructose corn syrup, it's incredibly inexpensive and found everywhere.
Men who eat a lot of soy have lower sperm count, low libido, decrease in testosterone, and even more disturbing physical issues.
Product photos below are links to high-protein meal supplements that are not soy based.