There is a well thought out reason for everything our Rishis prescribed to us. In India most of the fasts are in the monsoon season, July to November. This was so that people mostly eat meals only once a day and in general eat a lot lighter because our body’s digestive power is much weaker in the Monsoon and you are vulnerable to illnesses.
So by fasting you are both limiting your exposure to spoiled foods and not straining your system. Also, people tend to stay home much more and not go out as much during this time. So, accordingly, your body needs less fuel and eating less is healthy and balanced. Fasting in general increases one’s discipline and self-control, gives your body a chance to recover from the strain of metabolizing everything we shovel in it on a daily basis and renew its digestive powers on a lighter workload.
Unlike modern day fasting menus that are more sumptuous and vast in choice and quantity than everyday meals, we are traditionally meant to eat purer, simpler and less food when we fast to accomplish the goals of this day of discipline.