It's something that most people rarely do, these days. Before the "wireless" (ie, RADIO to all those without peculiar interest in history), any lone person doing a quiet task had minimal auditory distractions: city noises, fire crackling, water cascading, children vocalizing, animals ... doing what they do, other people about their business. Today, i know a lot of people who leave their televisions on all the time they're at home even when they're not paying attention to them. Many people out for a walk or jog are insulated from the real world by a pair of headphones. Unless an acute disruption happens which breaks through their noise-of-choice, they're not likely to notice a more subtle sound.
The same goes for "listening" to the body. People eat meals in company with others, be it family, fellow restaurant patrons, friends, etc; they chow down then get back to work, usually not paying attention to the quiet little responses of their bodies, to what they just ingested. If there's an "acute disruption" in the response of their digestive systems they'll notice, but might not with the more infinitessimal feedback.
I suspect that this is why so many people never notice that wheat or dairy or additives have a deleterious effect on them, until suddenly they experience reflux or ... something worse.
It would probably save a lot of expense and suffering if everyone who has ANY kind of health issue would keep a food diary, and consult it whenever an upset occurs. By noting coincidental malaise with the ingestion of certain foods (frequently consumed a day or two before), more people would get a clue that their dietary choices are problematic. You wouldn't see the constant denial that culturally-approved ingredients have a dark side.
In many cases, eating ANY of certain foods is the "eating too much" that self-appointed experts warn us against. Any wheat is too much for a celiac. Any booze is too much for an alcoholic.
After eating a perfectly-innocent paleo-approved breakfast this morning, i started feeling cold and edgy. SOMETHING in that breakfast didn't sit right. If i had been running around instead of doing my morning reading i would never have noticed.
There's nothing making more than a hum in this room, though there's a low murmur of a video on down the hall (J has been enjoying watching vintage television on Netflix recently). A winter Sunday in my neighborhood is usually pretty quiet too, though the muffled swish of tires rolling down our street comes quite regularly. My keyboard gives out only tiny clicks as i type. If my stomach gurgles or my joints pop, i hear it.
We have to pay close attention if we want to know our bodies' true responses to what we consume. That old chestnut, "listening to your body" is ONLY valid if we interpret its feedback correctly. We know it can be fooled by the addictive properties of certain foodstuffs, but it can also hint to us that our intake of important minerals is too low.
It can tell us that what we're eating is demanding too much response from organ systems -- too much carb for a struggling thyroid, for instance, or too much fructose-and-omega-six for the liver. It can tell us that leftover meat is taxing our ability to cope with histamines/tyramines. We can discover that normal quantities of healthyfruitsandvegetables for others are altogether excessive for us.
BUT YOU HAVE TO LISTEN. You won't notice that eating wheat-products gives you gas (as it does for my daughter) unless you have awareness that this doesn't happen when you eat rice. If you're getting a hit of dopamine from playing that video game, you won't perceive that ingesting certain foods results in depressive symptoms. If you're vicariously concerned for your favorite character in your favorite thriller, you won't notice that the "flutter" in your gut actually came from the four ounces of cheese you just ate.
Self-awareness is how we perceive that some foods make us feel good and others make us feel lousy. In the day before numbers-driven medicine, symptoms were how doctors knew there was a problem! But if you don't notice the subtler symptoms, you won't realize you really have a problem till that problem is acute -- at which time it COULD be too late.