Your body is not the same two days in a row

Every 24 hours your body rebuilds itself inside, and the numbers are not metaphors. Five lines to see it:

1. 300 billion new cells a day. Mostly red blood cells and gut lining cells, which live only a few hours. In four months you will have replaced your blood entirely.

2. 25 grams of skin drop off you. That is what a two-euro coin weighs. A large share of house dust is yours.

3. 1.5 litres of saliva, produced by six major glands and hundreds of smaller ones. Without them food would not even come away from the tongue.

4. 200,000 hairs grow 0.3 millimetres. All of them: scalp, arms, eyebrows. A hair cut today will have grown three millimetres within ten days.

5. 8,000 heartbeats an hour, depending on how much you move. That is close to 100,000 in a day, pumping 7,000 litres of blood.

Added up: about 200 grams that arrive and leave without you doing anything. When someone tells you «you are not the same as before», they are literally right, not poetically: if «before» was five years ago, neither your blood nor your skin is made of the same atoms with which you started reading this piece. And if you've made it here in two minutes, your heart has already beaten about one hundred and forty times without asking, and some forty million red blood cells have ended their shift.