Diet and Eating

In this season of eating and over-eating, I find myself once again amused by all of the self-help offerings on dieting and eating healthy.  As a somewhat analytical person, I find it difficult to give much credence to most of the advice. 

Many people say that diet is a simple matter of intake versus metabolic work.  If you consume X calories and the work that your body does is less than X, then you will gain weight.  If the work is more than X you will lose weight.  I have seen these types of calculations done based on the amount of exercise one does each day.  I don't buy it!

As an engineer, I think in terms of conservation of mass and energy.  Food is mass, but it is also stored energy.  Food and drink are consumed.  A certain part of this food and drink is excreted, either as urine or feces.  The amount of this excretion can vary dramatically from day to day or over longer periods.  Moreover, the amount of energy that is extracted from our food as it goes through our digestive tract may be up or down regulated based on the body's needs. The energy content of this excretion would be important in any calculation of net energy or caloric gains/losses.  Has anyone measured this?

The body also converts part of the food and drink into energy.  The energy used by the body might be characterized as typical daily metabolism and work (which may vary considerably or may be fairly consistent – does anyone really know?) as well as extra work that may be associated with exercise, stress, climate conditions and other external phenomena.

Some of the consumed food and drink may be converted to other forms of stored energy and deposited somewhere in the body.  And conversely, some of the stored energy in the body may be converted into energy to accomplish the work of the body. The control functions for these mechanisms are probably poorly understood, yet they are essential to a full understanding of the process.

Thus, there are many parameters in the diet equation – intake, excretion, exercise rates, various forms of metabolism and their rates, conversion rates and efficiencies, etc.  These parameters may vary dramatically from person to person and from week to week.   

Some of these parameters may be affected by the body’s desire to maintain an equilibrium state.  For example, I have been on several cruises where I have eaten massive quantities of rich foods.  Doing a basic energy equation of the type promoted by many diet experts would indicate that I should be gaining weight rapidly during the 10 days or so of that cruise. 

But my experience is that I gain no weight at all!  I do notice that my excretion seems to be at a markedly increased level, if I may be so indiscreet!  Can it be that my body is trying to maintain its current ‘form’?  I have no doubt that if I were to continue that type of culinary indulgence I would soon begin to gain weight, but I am not eager to run that experiment!

I suspect that the body has a certain inertia in terms of its weight and size.  As evidenced by the challenges facing dieters, it appears that the body fights change even when it is not in an ideally healthy state.  The good news is that this helps us avoid ballooning every time we go through a rough patch with food, but  the bad news is that if you are fat it may be more daunting to convince your body to stay trim even when you are successfully cutting your calories.  But in the end, if you eat less calories than you burn (assuming you can calculate these amounts correctly!), the law of conservation of energy will eventually favor your discipline with a good result!