Analysis of Weight Loss, Weight Gain and
Energy
Obesity Comments
Obese people often tell stories of progressive lifelong weight gain, whereas
few talk of a progressive lifelong increase in food intake.
Other common statements of the obese persons (especially women) which
may be difficult to explain are: 1) that there are many other persons
(especially men) of the same age and height who eat much more than them
and still are much thinner than they are; 2) that they do not lose weight
even staying on a diet; 3) that, after losing weight on a diet, when they
go back to the previous food intake they stabilize at a higher weight
than the previous one.
Weight Gain - Thermodynamics
Like any other natural entity, human body must obey physical laws, in
this case represented by the first principle of thermodynamics, according
to which energy cannot be created nor destroyed, but only transformed.
Consequently, all excess energy introduced must necessarily modify the
internal energy of the system, being retransformed in potential chemical
energy. And, since our main energy store is fat, an energy intake greater
than energy expenditure unavoidably causes an increase of adipose tissue,
which is always accompanied by an increase of lean body mass, and thus
an increase of body weight.
Weight Loss - Energy Expenditure
The weight gained or lost by a person with normal body weight is composed
of two-thirds adipose tissue and one-third lean body mass, which consume
about 5 and 40 Cal/kg/day, respectively. One kilogram of such weight consumes
then about 17 Cal/day. Therefore, if a normal weight person increases
or decreases permanently his/her energy intake by 100 Cal/day, his/her
body weight will eventually increase or decrease by about 6 kilograms,
which produce an energy expenditure equal to the variation of energy intake.
Considering that 100 Calories represent more or less the energy content
of a cappuccino, the corresponding weight change appears decidedly greater
than what is commonly believed.
Source: International Federation for the
Surgery of Obesity. Nicola Scopinaro, M.D.Professor of Surgery (Honorary
President of IFSO) , University of Genoa Medical School. www.obesity-online.com
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