Why the body gives way in your fifties: three things that were actually measured

The blood work is fine, the blood pressure is where it should be, the doctor says there is nothing wrong. And you know it is not the same as before: the stairs take longer, a bag of cement is heavier than it was five years ago, and after one bad week you need two to get back to normal.

It feels as though this happened suddenly, almost overnight. It did not. Three things here have actually been measured, and all three begin long before you notice them.

Deep sleep leaves quietly, and early

A night is not the same from beginning to end. Part of it you sleep lightly and part of it deeply - deep sleep being the kind you are hard to wake from, the kind in which the body repairs itself.

Scientists followed 149 healthy men aged sixteen to eighty-three and measured how much of the night each of them spent in that deep sleep. In the youngest, those up to twenty-five, it was almost a fifth of the night. In men between thirty-six and fifty, barely three percent was left.

So deep sleep is not lost in old age but much earlier, and growth hormone, the substance that patches up overnight what the day used up, falls along with it. Which is why eight hours of sleep at fifty is not the same as eight hours at twenty: you sleep just as long, but not as deeply.

Strength goes quickly and comes back slowly

Eleven healthy people, average age sixty-seven, agreed to spend ten days in bed, and that was enough for their legs to weaken, for them to lose the speed with which they could push off, and for their stamina to drop.

Now picture an ordinary bout of pneumonia, a knee operation or a cast on your leg - it is the same thing, only nobody is measuring. And the difference between a young body and an older one is not in how much is lost but in the fact that a young body gets it back on its own, while an older one has to rebuild it on purpose, and slowly.

Muscle hears the same call less well with age

When you eat something with protein in it - meat, eggs, cheese, beans - a substance called leucine rises in your blood and acts as a switch, telling the muscle it is time to build.

A group of scientists went through 29 studies to see how much that switch is really worth. They did not agree on everything, but they did on one thing: an older body needs more protein at once than a young one before the switch will flip at all.

How much? The international PROT-AGE expert group recommends that a healthy person over sixty-five take one to 1.2 grams of protein per kilogram of body weight a day, and more for those with an illness, up to 1.5 grams. For someone of eighty kilograms that is between eighty and a hundred grams a day.

How it is spread matters just as much. The recommendation is 25 to 30 grams per meal, across three meals, because one large dinner does not make up for two thin meals before it. Toast, fruit and coffee comes to barely ten grams - enough to register in a young body, not in an older one.

What can be done about it

All three pull in the same direction, and it is the one the authors of these studies give themselves: protein spread across three meals rather than all in the evening, legs that get loaded regularly and do not sit still for too long, and sleep that is not cut short - because the deepest kind, the kind that actually repairs the body, is growing scarcer with age anyway.

And one more thing, for honesty’s sake. The video that prompted this piece gives five reasons and there are three here - for those three we opened and read the studies, and for the other two we found nothing to back them up. Better three that have been checked against the science than five that sound good.