How To Stay Lean & Fit

I have always believed that you need to nourish yourself continuously, and ensure waste generated is also disposed continuously. 
I have by a simple diagram depicted what I wanted to say.

On the left half is a depiction of two steel tubes held together by a rubber balloon open at both ends.

Assume we need 1 pail of water daily, we regulate the in-flow to ensure there is no inflation pressure on the balloon and at the end of the day the pail is full.

Should we shut the exit and decide to collect the water once a day, then the inflation pressure gets reflected and the balloon swells. The balloon returns to normal when the valve is opened. This constant expansion - contraction also wrinkles the balloon. 
This can all be avoided if we regulate the inflow and do not regulate the outflow.
The Human body is like the steel tube shown above with the stomach similar to the balloon.
If we need 100 calories a day, the easy way is to divide it by the 16 waking hours, which means we need 6.25 calories every hour. No ballooning of the stomach, no wrinkling of the skin.