I'm in my mid-20s and have always been in decent shape. But, about a year ago, I hit a wall and started to go bald from the temples rapidly. Probably one of the biggest breaks in my life as I implemented the following:
ImmortalHair The guy's a genius and fellow trader (doesn't even attempt to make money off of it)...
The Warrior Diet & The Anti-Estrogen Diet by Ori Hofmekler.
Since:
My hair quit falling out and regrew almost totally.
-I'm in better shape now than when I was a teenage athlete (only biking about 50 miles/week).
-Increased libido
-Almost no body fat
-Better focus, increased mental clarity
-Haven't been remotely sick even once since I began the above.
If you want to drastically improve your life do the following:
-Eat a low [glycemic] GI / GL diet.
-Eat mostly vegetables and meet. Dairy OK.
-Get organic and grass fed meat when at all possible.
-Watch out for estrogen compounds that are in god damn everything from tap water to laundry detergent to beer and are highly absorbable through the skin.
Before I did it I would have said BS, and been skeptical as hell. Now, I know it to be true.
So baldness is most certainly not a purely genetic thing as people like to tout. I am very confident it is mostly related to modern diet. And you can do something about it without turning yourself into a woman (Propecia [never touch it!]).
As an example, in my early 20s I worked on an incident management team; guys who would travel around the country and deal with disasters. 90%+ of these guys were bald and/or fat. It wasn't their genetics, it was the constant bombardment of horrible processed/fast foods. Stress, 14 hour work days, but mostly the spiking of their blood sugar over and over to keep going. Be skeptic if you want, but look up insulin resistance, syndrome x, diabetes, heart disease and hairloss -> very high correlations, if you refuse what I see as causation.
Also calories are an irrelevant unit for human diet. I could eat 6,000 calories of meat, dairy and vegetables and be thinner than someone who eats 2,000 calories of Wheat Thins and works out more. Those caloric restriction mouse diet studies increased life span likely due to the lowered insulin activity.