Being a Carbon Life Form we need to consume carbon energy - food to sustain ourselves as a living body. We can also can use energy in form of sunlight to sustain the body, that requires a little practice.
As a rule most people eat three times more than what is essential for good health. When we eat any food there are two factors which are most important in consuming it. First is the Nourishing value and the Second is the pleasant sense of taste.
For example if one was given a bowl of shelled peanuts and said you need to eat 40 nuts only as the required refuelling for the body.
In this experiment of eating peanuts to satiate hunger you see how we eat mentally when for good consumption and use of resource we have to consume much less.
If you ate one peanut at a time, and only have the second one after the first was chewed and swallowed well completely, you could take 20 minutes to finish the 40 nuts. You took in some air while eating and also the time base tells your brain you have been eating for 20 mins and starts sending signals of fullness.
On the other hand if you ate 10 nuts at a time and took 30 seconds to chew it you could finish all the nuts in 2 minutes. Also the fullness factor would only come after 20 morsels of 10 nuts each. You end up having 200 nuts to feel full. This is mental eating.
It is the same taste of the peanuts when you eat one peanut or you eat 10 at a time.
In this experiment of eating peanuts to satiate hunger you see how we eat mentally when for good consumption and proper use of resource we can consume much less.
This happens with air also. We breath air with 21% oxygen and exhale with 16% Oxygen. We only absorb 4 % of Oxygen every time the 15 times we breath in a minute.
If we reduce the amount of breaths to 4 times per minute then we would absorb more than 6% oxygen.
We learn that to err on the side of more becomes part of our learning and as such defines our goodness scale to measures all things in life.
We want to feel the fullness in the stomach and that defines - my hunger is satiated.
Any thing less would mean that you were not getting enough food.!
As an example, the food servings given in a Texan diner are so huge if you are not used to it but adequate to the people used to that size of serving.
When I joined the naval training as a cadet officer the daily meals given was considered not enough. I had come from home where a feeling of fulness had to be achieved after eating a meal.
Unknown to me the food serving on the training ship was scientifically calculated to be more that adequate for a growing kid of 17 years.
We can train ourself to only to nourish ourself, just like we refuel a car - no more no less.
This will ensure less processing of food by our digestive system and also reduce the amount of nutrients lost in the excreted waste.
We would do this to ensure good health by avoiding overeating, and collectively, if the entire world agrees, the living planet will have that much less nutrients to process and the associated release of biogas.
Our learning point here is that nourishment by way of food should be what the body requires to operate efficiently- any excess should be avoided.
The portions should be adequately sized and tasting well. We have come to an unhealthy conclusion , taste is important and portioning depends on how much you require to be full. The sense of taste was designed to reject food the taster did not like.
What to eat, when to eat, portion and recipes are not in the scope of this post only the fact eat less and you will be healthier.
It is all your own will, to eat to live or to live to eat.
There are more health issues with over eating and there ever is with under eating.
So you can attach minimum 15 more years to your lifespan if you choose to eat to live.