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Nutritional Influences on
Muscular Development and Fat Metabolism
by J.E. Grogan
for Show Feeds, Inc.™
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Carbohydrates:
Carbohydrate food stuffs consist primarily of grains,
vegetables, fruits, beans, peas, legumes and also sweeteners such as
cane sugar, honey, molasses and sorghum.
The body
metabolizes carbohydrates by both catabolic and anabolic pathways.
Since glucose is the preferred energy fuel, most carbohydrate
absorbed is used to generate glucose. A small amount of consumed
carbohydrates are anabolized to storage glucose or glycogen found
mostly in muscle cells and the liver. When the level of glucose
entering cells is inadequate for energy needs, fats and then
proteins are broken down to supply those energy requirements.
Implicit
in this biological chain of events is the ability of carbohydrates
at proper dietary levels to protect lean mass (muscle) from being
broken down and to increase the amount of fat that is burned for
energy; thus increasing the lean (muscle) to fat ratio.
Glucose is
broken down in a process known as glycolysis into two pyruvic acid
molecules. The pyruvic acid then is further metabolized by combining
with coenzyme-A to enter in the Krebs' cycle for the production of
ATP - the energy currency of the cell - to do cellular work. The two
major sugar controlling hormones are insulin and glucagon. Insulin's
primary function is to pull glucose from the blood and deliver it to
the cells for the generation of a usable form of energy - ultimately
ATP.
The
primary function of glucagon is to increase blood sugar levels if
they are too low by activating the release of glucose from the
liver's stored glycogen. A balanced relationship between insulin and
glucagon maximizes the generation usable energy from glucose. This
can protect body proteins and can increase the fat burning
processes. Many other hormones exert an influence on glucose levels
and metabolism.
An
important recent consideration in carbohydrate metabolism in
non-ruminants pertaining to fat loss or fat gain revolves around the
glycemic factor or index. The more rapidly a carbohydrate can be
converted to blood sugar (glucose) the faster and with greater
efficiency can this carbohydrate be converted to fat. The reverse is
also true - that the less rapidly a carbohydrate is converted to
blood sugar (glucose) the less likely it is that the carbohydrate
will be converted to fat.
Many
common feed carbohydrates have a high glycemic factor e.g. corn,
wheat, oats, sweet feeds. However balancing and stabilizing these
quick acting carbohydrates with adequate and proper balance of
proteins, fats and carbohydrate stabilizing nutrients can minimize
the storage of excess fat from these high glycemic carbohydrates;
thus the lean to fat ratio can be protected and improved upon.
Proteins:
Dietary proteins are "of first importance" for the maintenance and
integrity of all body tissues and cells. Complete or high biological
value proteins: meats, milk and eggs, maintain and build the body's
strength and lean mass (organs, muscle, bone) optimally. Proteins
are present in all cells and are utilized to make hair, skin,
hooves, hormones, enzymes, structural proteins, muscle, immune
compounds, cell-membranes and internal cellular material. Acid-base
balance is regulated by proteins and two specific proteins, actin
and myosin allow for normal muscular contraction. Proteins are also
involved in the transfer of genetic information. The individual
components or building blocks of protein - amino acids - singularly
or in combination are also involved in energy production, hormonal
balance and a variety of other metabolic regulations.
Proteins
are used rapidly and have a high turnover rate. The state of protein
balance exists in the normal healthy body when the rate of protein
breakdown is equal to the rate of protein replacement.
There are
basically two types of protein (nitrogen) balance, negative nitrogen
balance occurs when tissue is breaking down faster than it can be
replaced. This can cause a drop in muscle mass and a lowering of the
lean to fat ratio. Positive nitrogen balance occurs when the protein
build up occurs at a faster rate than tissue is breaking down. This
can characterize any condition when large amounts of tissue are
being synthesized including an increase in muscle mass or volume.
As
important as the optimal amounts and balance of dietary proteins are
for protecting and building lean mass, (especially in non-ruminants)
an excess of dietary proteins can also be stored as body fat.
Protein
Metabolism:
In protein metabolism, anabolism (or building) is primary and
catabolism (burning) is secondary. In carbohydrate and fat
metabolism the opposite is true - catabolism is primary and
anabolism is secondary. Proteins are primarily tissue building
foods. Carbohydrates and fats are primarily energy supplying foods.
Growth and
development is highly dependent on the endocrine system. This system
consists of several endocrine (ductless) glands that secrete
hormones into the circulatory system. Hormones are chemical
substances that affect a gland (or organ) or, in some cases, all
body tissues.
The
endocrine system is quite dependent on optimal nutritional status to
maximize hormonal production and release. The stabilizing and
balancing of hormonal levels can go a long way toward moving the
metabolic processes in a direction to increase muscle mass and
increase fat catabolism. The primary hormones of interest in this
discussion are the following:
-
Thyroid
Hormone
-
Insulin
-
Growth
Hormone
-
Testosterone
These are
not the only hormones involved in fat and/or muscle metabolism, but
at this time are deemed among the more important.
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