Fat storage as a disease causing process has received much publicity.
Whenever food is abundant, humans and other animals overeat and get fat. What is
biological purpose of fat. What are the benefits of fat storage?
Dietary fats are a heterogeneous mixture consisting of about 93%
triglycerides, 6% phospholipids and lesser amounts of sphingomyelins,
glycolipids, cholesterol, and phytosterols. Excess intake of animal fats has
been associated with several major diseases: atherosclerosis, which leads to
heart attacks and strokes, cancers of the colon and breast, and obesity. Fat is
energy dense, supplying 9 Kcal/gram. Dietary fat surplus is stored as body fat,
and high fat intakes are associated with obesity, except in Eskimos who continue
to follow traditional patterns of sustained hard work in extreme cold weather.
Current recommendations for fat intake are shrinking progressively from 35% of
total calories to 20%. Typical American diets contain as much as 42% fat, a
surplus. Our needs are supplied by 15-25 grams of fat per day, 1-2% of total
calories for adults and 3% for infants. Fat intakes close to minimal need may be
desirable, especially for those at risk of fat-related disease. The Alpha
Nutrition goal for fat intake is 10-14 % of daily calories, with 70% as
polyunsaturated vegetable oil. Fat is usually fully digested, with less than 5%
remaining unabsorbed and excreted in the feces. If fat digestion is impaired by
pancreatic enzyme deficiency, an oily diarrhea results, with foamy, floating
stools (steatorrhea). Ingested fat mostly consists of triglycerides. The
molecules, glycerol, acts like a rack to which three fatty acids (FA) attach.
Fat Storage Benefits
Fat storage does have several purposes and offers benefits. Everyone stores
some white fat to provide insulation and body shape. Our facial contours are
constructed from fat. The shape of women’s bodies differ from men’s bodies
because of carefully designed fat deposits in the breast, abdomen and buttocks.
Extra fat is a good insulator and keeps you warm. Extra fat is buoyant and helps
you float in water. Marine mammals are all fat because they swim in cold water.
Eskimos are fat so that they can survive cold winters when food is scarce. Brown
fat is a source of heat; calories are burned in brown fat to warm the body.
Children hear stories about prudent animals who prepare for the future and do
well and imprudent animals who only live for the present and perish. The child
knows that squirrels store nuts for the winter and bees survive the winter by
eating the honey they made during the summer. Bears get fat in the summer so
that they can hibernate during the winter. The challenge of a seasonal food
supply is expressed in acquisitive behavior, gaining weight and hoarding food.
Most humans seem to have an odd mixture of prudent and imprudent behaviors and
only a small number appear to be good at long-term planning. Humans are better
at consuming on the run and adapt to changing conditions.
Humans are relatively tolerant of short-term food deprivation and take
advantage of surplus by feasting and celebrating. The party aspect of human
behavior links us strongly with carnivorous predators who gorge when they have
made a kill and then rest.
Anxiety about the future vanishes when you are full and returns as a viable
concept when your hunger returns. Predators are not always successful in the
hunt and have to endure periods of deprivation or even starvation. Humans like
other mammals store fat to supply energy when food becomes scarce. The more fat
you store, the longer you can survive starvation. In other words, there is a
built in tendency to binge eat and gain weight when food is abundant.
If you accept that the overweight condition is caused by the lack of famine,
absence of hibernation and/or the failure to schedule sustained athletic
training, you are better prepared to lose weight. All overweight people would
become slimmer people if they ate less food.
All overweight people would become slimmer if they hibernated over the winter
and did not eat food for 4 months. All overweight people would become lean
people if they as trained hard and long as an endurance cyclist. Long-distance
athletes are the leanest people in town because sustained exertion causes muscle
cells to use fat as fuel. If you train long enough and hard enough, most of your
stored body fat is burned as fuel.