Humans are diurnal creatures and we have evolved to hunt and eat our food in the daylight hours to keep us safe. It wasn't until very recently in our evolution that the concept of a big, complex, late, elaborate dinner began to become the norm. Until the industrial revolution, people were living more in line with their circadian rhythms, but with people working in factories and technologies began to improve, the dynamic of the work and home life began to shift. Today, we eat at all hours of the day and the night! We are on no schedule to regulate our digestion, and we eat way too much!
Ayurveda teaches us about the energies of the day and how to align with them to live a life of longevity. If we refer to the doshic clock, we should be eating or digesting and metabolizing during the time of the day with the most fire, dominated by Pitta dosha. In Ayurveda, metabolism is called Agni, and it is one of the most important concepts of the whole medical system. If we can keep our inner fire, our Agni, our digestion, strong, we can eliminate much of the digestive pain and discomfort that will eventually lead to all types of chronic illness. Ayurveda believes that all disease begins in the digestive system. So keeping this system healthy is our first priority as an Ayurvedic practitioner.
Eating a light, early dinner allows us to begin digestion before we go to bed.. If we can make it into bed around 10pm, our inner fire, Agni, Pitta, heats up and the liver begins to cleanse, scrub and eliminate those things left over from the day's meals and previous days meals that do not serve us. This includes food we haven't fully digested and toxins that have accumulated from outside factors or from pesticides and chemicals in our food. This is a free, mini-detox that we get every night!!!!!
The body cannot go into this deep cleaning mode if it is still digesting it's dinner, especially if it was a big hard to digest meal. This is also why we want to eat as lightly as we can so that it is easy to digest (think plants) and the body is free to do its work while we sleep. With a full belly, the breath is more shallow, which leads to less oxygen in your blood. Which equals less life force energy (prana) and less oxygen in your blood (less energy). This work is so vital to our bodies, our health and our everyday experiences. It is giving the body these periods of rest and digest where it can clean is what will play a big role in eliminating inflammation from the body. Inflammation is the root cause of chronic disease which has become an epidemic in our culture.
Our bodies are made to handle inflammation, the problem is when we are constantly doing things that create inflammation, our body is forced to be constantly handling the inflammation. This takes vital resources away from the other cleansing processes that are supposed to be going on while we sleep (the mini-detoxes included). Due to this constant demand of the body to handle low chronic inflammation, there an effect that accumulates over time. If the constant inflammation get bigger than the body can manage it will lead to illness.. its a compound effect on the body.
In summary, keep to a light, early dinner. Eat as much as you need to satisfy you during lunch. Allow your body to do its work each evening. This will lead to a positive compound effect over time that will change your health dramatically.