It is really a difficult question to answer. The quantity of food that we take varies based on mood, what we had eaten on previous meal, what is the nature of present meal, whether the previously taken food is completely digested or not etc. Though there are uncertain factors, there are a few general rules that help to answer – how much food to eat per day.
Based on hunger:
The rule of natural urges of Ayurveda states that – you should eat only when you are completely hungry. You should eat till the hunger is satiated. When you are hungry, it indicates that the digestive enzymes are completely produced to optimum extent. Hence the food that you take will be digested well.
You should eat till the hunger is satiated. While taking food, if you stop feeling hungry, that indicates that the food that you have taken matches with your digestion strength. Hence, it is time to stop eating. If we eat, beyond hunger, then there is extra pressure on digestive enzymes and some part of food may get left undigested. This is the leading cause of indigestion and altered metabolism. This is how ‘Ama’ develops, as per Ayurveda.
Sometimes we get fooled by our mind, of hunger, because we like the food on the table very much. In those tough circumstances, we have to be strong enough to listen to our stomach, carefully, ignoring our mind.
Just before the hunger is totally satiated:
This is what we hear from our parents and grand parents. We should get up from the bed when there is little sleep still left in our eyes, we should stop eating when there is little hunger still left in our tummies. This argument also has some weight. This practice will always make sure never to over-eat. This practice also gives good control over our mind and sense organs.
Time for the food to get digested:
The quantity of food should be such that it gets digested before we take food next time. So, if you are taking only two meals per day, then relatively the quantity of food can be more, so that it keeps you energized throughout the day, till the second meal is taken at night.
If you are accustomed to 4 – 5 meals per day, (which is recommended in diabetics, certain type of gastritis patients etc), the quantity of food should be smaller.
It sounds more like defining the upper limit of food quantity. But it also defines the lower limit as well. Meaning – the food quantity should be not so high that when the next meal time arrives, you are still not hungry and it should not be too low that before next meal time, you already start feeling hungry.
Based on Guru Laghu –
Ayurveda classifies foods into two main categories.
Guru – heavy, those foods that impart heaviness to the body, those, after taking which, you feel heavy, those which take longer time to get digested.
Example: wheat, Fresh wine, black gram, cow pea, lablab bean, mutton, Fish, ash gourd, dates, Jamun fruit, onion, garlic, cow milk, buffalo milk, jaggery, honey, sesame, dairy products, sweet products, fried foods, etc.
Laghu – light, those foods that impart lightness to the body, those, after taking which, you feel light, those which take shorter time to get digested. They are pretty easily digested.
Example: old rice, Green gram, goat milk, camel milk, Chick pea, lentils, grass pea, lemon, old wine, Moringa (drum stick), pomegranate, cumin seeds, hot water, coconut water, butter milk etc.
Foods that are heavy, should be had less in quantity. – About half to one third of stomach.
Foods that are light, can be had more than those with heavy, up to one third of stomach.
How to decide if one third of stomach is filled up or not? – It is left to your own observation. It is that point of time while you take food, that you no more feel comfortable.
Time of the day: Usual rule is to have good amount of breakfast, moderate amount of lunch and less amount of dinner. Makes sense, because, you will require more calories in the morning, moderate in the afternoon and lesser at night.
So, these are some of the criteria that are explained in Ayurvedic text books. Though most of these are subjective, I hope that with experience and self observation, you can decide on yourself about the right quantity of food.