Every contraction your body makes — a step, a lift, a thought — is paid for with a molecule called ATP. And the reserve tank your body keeps for regenerating ATP quickly is creatine. Roughly 95% of it sits inside your skeletal muscle, with a small but critical share in the brain.
Here is the problem: your body has no way to bank a surplus. You turn over a few grams every single day, whether you train or not. What you don't replace, you lose.
Your liver and kidneys make about half of what you need. The rest has to arrive through food — and the food in question is red meat and fish, in volumes most adults over 40 simply do not eat. A pound of raw beef carries roughly 1 to 2 grams. Cooking destroys a meaningful share of that. Vegetarians start lower still.
Which means the majority of adults are walking around with muscle and brain stores that are chronically partially empty — at exactly the age when the tissue starts to erode by 1% a year.
So before you decide the tiredness is your job, the soreness is your age, and the fog is your phone, check yourself against these seven signs.