The Basic Constituents of Food
Table of the Three Basic Macronutrients: Fat, Carbohydrate & Protein
We humans eat a lot of things that can be called nutrients, but there are three
basic chemical types of food that account for the vast majority of our calorie
intake and they are fat, carbohydrate and protein. These are called
"macronutrients" because unlike say, iron, we need very large amounts of them
and because, in addition to satisfying specific nutritional needs, macronutrients
are our main fuels and it is by metabolizing them that we can capture and store
the energy we need to stay alive.
For purposes of weight control, several important facts stand out. First, fat is
far and away the "richest" macronutrient, supplying more than twice as many
calories per unit mass than the others. Second, fat is the most easily
assimilated macronutrient and therefore has the lowest "thermic effect". Protein
has, by far, the highest thermic effect. Thus fat is a caloric "double whammy"
being both calorie-dense and easily digested. Protein on the other hand, has far
fewer calories per gram and nearly 30% of those calories are lost to heat during
digestion. Carbohydrate falls in the middle. It is easy to see why fat reduction is
likely a very important part of a good weight control plan.
On the other hand, fat also satisfies hunger the most and tends to have the
greatest "staying power" after eating, contributing to a feeling of fullness that
last many hours thanks in part to fat's tendency to delay gastric (stomach)
emptying time. Protein is also good at satisfying hunger as are many high-fiber
complex carbohydrates, but sugar is another matter. Sugar tends to satisfty
immediate hunger, but the effect is short lived because of insulin produced by
the pancreas in reaction to sugar.
Which Macronutrient is Worst For Weight?
Fat is generally the macronutrient to limit the most in weight-control, but sugar
is a close second. On the other hand, we need a certain amount of fat to
supply us with "essential fatty acids" that cannot be made by the body so it is
unwise to reduce daily fat intake below about twenty grams. Sugar can be
safely elimated entirely, but many people find this rather hard to accomplish and
it is probably unneccessary so long as sugar intake is kept low.
Which Macronutrient is Best for Weight?
Actually this is a rather silly question (sorry) since any calorie source, when
consumed to excess, will lead to fat storage, but let's tackle it anyway. It might
be tempting to think that a super high protein diet is best for weight loss, and
this might in fact be true except that it is harmful to the kidney to consume too
In the end, what macronutrient information informs us of is that a low-fat,
moderate protein, high carbohydrate diet is likely to be the best bet for most of
us. A key to making this sort of diet effective is to consume carbohdrates that
are low on the "glycemic index". This then is our next topic.
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