J. F. BROCK 
Obesity. This term is used in the sense of increase in the 
amount of adipose tissue relative to lean body-mass and parti- 
cularly skeletal muscle mass. It is often, but not necessarily, 
associated with overweight—the term does not necessarily 
connote obesity. 
The adverse effects of overweight on mortality are adequately 
documented by insurance statistics. It must be admitted that 
statistical proof that the direct association between mortality 
and overweight is due to obesity 1s not conclusive; this gap in 
knowledge is due to the practical difficulty of measuring obesity 
in exact figures. But few critical observers would deny the 
high degree of probability which is generally assumed. Obesity 
is also reasonably assumed to be responsible for much morbidity 
from osteoarthritis and musculo-skeletal deformities, bronchitis 
and emphysema, diabetes mellitus and hypertension. The 
statistics of the Metropolitan Life Insurance Company of the 
U.S.A. have shown that for a man of 45, an increase of 25 
pounds above standard weight reduces his life expectancy by 
25 per cent *. 
The causes of obesity are multiple and complex. Inability to 
control appetite and so match caloric intake to energy expen- 
diture is the major practical factor. Here sophistication of 
foods is a major cause. Natural vegetable foods mostly contain 
enough cellulose residue to give the stomach a comfortable 
sense of repletion before calories have been consumed in excess. 
The consumption of sugar and refined carbohydrates is without 
this built-in restraint. The culinary art and twentieth-century 
food technology, including food advertisements, have set 
endless traps of sight, taste and smell to break down the 
restraint of appetite. Animal selection and scientific feeding 
have, through the meat and dairy industries, contributed to 
raising the percentage of fat calories from 15 per cent or less 
in primitive agricultural communities to 45 per cent or more 
among sophisticated population groups. This is conducive to 
over-consumption of calories. 
Constipation. ‘The refining of foods by exclusion, inter alia, of 
much of their natural cellulose has contributed to a widespread 
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