One that stuck out at me this week was the phrase, "If you aren't hungry enough to eat and apple, then you're not hungry"
On the surface, this makes sense. If you are hungry, you will eat anything right? Yes, if you are starving. But if you are not starving, you have options. Either you are not really THAT hungry and you can walk away. Or you can have a drink of water. Or you can eat. But if you want to eat shouldn't you be willing to eat a healthy apple (or banana or pear or carrot?)
There are all sorts of "Hungry." Our bodies are run by chemical reactions. We need certain vitamins, minerals, macro nutrients, enzymes etc. If you are lacking in protein, then an apple will not satisfy your hunger. If your body needs magnesium, then it might legitimately need chocolate - not an apple. Or if you haven't eaten enough fat, then you might be craving cheese for a reason - again, not an apple.
So it's not so easy to sort out. If you haven't eaten all day and are really, really hungry, than an apple would be great... and probably a bunch of other stuff too!
If you are not "hungry" but bored, then almost everything but the sugariest junk should be unappealing. In this case, the mantra makes sense.
But most of the time - when you read a fitness/health mantra - dig deeper. There is more to it than a simple phrase!