Age Affects Men's Nutrition

Metabolic rates decrease as age increases, and physical activity also decreases with aging, thus, energy needs tend to be reduced with aging," says Flakoll. "However, good quality protein and vitamin and mineral needs continue to be very important."

It is important for diets to be more nutrient dense as men age, Flakoll notes. Quality nutrients are important to maintain men's immune function and overall health, as well as preventing bone loss, eyesight loss, and muscle loss, he says, adding that "prevention of oxidative damage and maintenance of tissue health via antioxidative vitamins and minerals become more important as men age."

Agnew and Marin agree, saying, as we age, lean muscle mass is gradually replaced by fat. As the body composition shifts towards more body fat, calorie requirements decline. That's why if you keep your same eating pattern in your 40s as you did in your 20s, you will most likely gain weight.

They added that exercise must be part of the regimen to help maintain lean muscle mass. Part of the reason we may see less lean muscle mass among older men, may be because there is also a decrease in the number of men who do weight training as they age. Exercise can help maintain muscle mass and help maintain a "fast" metabolism as we age.

And although there are many supplements out there that promise to help men as they age, Heber says he's seen little convincing evidence.

"The benefits of hormone or pre-hormone supplements has not been proven in the literature," he says. "Certainly, it may seem to make sense to use these types of hormones to make up for deficits as men age. However, publications of good clinical trials that provide valid assessments of risks and benefits are lacking in peer-reviewed journals."