As you'll find if you mix up the diesel and unleaded pumps, cars don't work with the wrong fuel.
We kind of know this, just as we're aware that babies aren't likely to take to spare ribs, and should remember that you must never, ever give dogs macadamia nuts.
So why, if we're this astute when it comes to the nutritional needs of cars, babies and dogs, do we seem to ignore that having a healthy diet is crucial to our own physical and mental wellbeing?
Why do we sometimes think it's fine to shovel down junk without expecting to see an associated decline in our health and all-round happiness?
Of course there's a lot of psychology surrounding what we eat and why. It can get complicated.
But one thing that generally holds true is the principle adhered to by computer experts, among others: garbage in, garbage out.
You'll have choices today about what you eat. Try to make as many sensible ones as possible.
Your mind and body will thank you, even if your willpower gets a bit challenged.