At a recent seminar I attended on auto-immune conditions, the lecturer spoke briefly about endotoxicity associated with eating.
Endotoxins are toxic byproducts produced within the body and eating and digesting is one source of these toxins. These toxins can damage and age cells in the same way as exotoxins - toxins from external sources such as pollution, drugs, alcohol etc.
Whilst we need to eat to live, food can also be detrimental to health, invoking an insulin response, some allergic responses, inflammation and this endotixicity.
You've probably felt this affect anytime you've eaten a particularly large meal or a meal that was particularly unhealthy. Feeling foggy headed, tired, headachy, almost as if you're hungover are classic symptoms. Even healthy foods can have an endotoxic effect, just on a much smaller scale.
The answer obviously isn't to stop eating but it's worth bearing in mind that over-eating and eating when you're not hungry is creating unnecessary endotoxins in your body.
This is also a reason not to constantly graze as this will produce a continous stream of these endotoxins without giving your body a break - whilst rushing your meals isn't desirable it can also be harmful to drag them out too long. Eating a meal should generally start and finish within an hour and main meals should be 4-5 hours apart to give your body at least 18 hours in 24 when you're not eating and preferably just drinking water to help detoxify.