Yes, yes, it is true. It does take 20 minutes for your brain to register what is in your tummy. Do most people take those 20 minutes before heading for seconds. Nope!
Why is it important to take at least 20 minutes (or more) to eat? Your tummy is the size of your fist. Not as big as you thought? So, if you are going to put food into that small space, it is really important to eat slow and also pick quality food.
We, as a country, eat the same way we do everything else, way too fast. We eat standing up, in front of the microwave, driving in our car, talking on our phone, and we rarely eat sitting down. All this "fast" eating = fast weight gain and fast onset of other health problems.
My challenge to you, during your next meal, set a timer. If it takes less than 20 minutes to eat your major meal, you're not taking the appropriate time your body needs. Next time, smell your food before you take a bite, chew your food (more than once or twice), taste the flavors of what your eating, and enjoy it for at least 20 minutes. Chances are, you will be satisfied after one helping, not go back to seconds and appreciate 20 minutes of not having to multitask.