I’m happy that I can put what I've been learning in class to
some good use by helping you with your desire to eat healthy. Whether you have tried managing your diet before or not, I'd like to help you derive satisfactory results. Both peer pressure and poor nutrition results can lead people to give up. Many people have an intolerance
for soy, dairy, or wheat, so we will leave it out. I hope to
explain the concept of metabolism and how your body utilizes what you eat, and
I’ll make some recommendations for ingredients to use in your meal planning so you can maintain a healthy weight.
Let’s start by explaining the concept of nutrition. We have all heard the phrase
“balanced diet,” but what does that really mean? According to Princeton
University, a balanced diet is one “that contains adequate amounts of all the
necessary nutrients required for healthy growth and activity, (Princeton, 2013).”
Nutrients are the essential substances we get from our food, and can be
described in three categories: macronutrients, which are carbohydrates, lipids,
and proteins; micronutrients, which are vitamins and minerals; and water, which
is able to dissolve solutes in the body (Haas, 1992). Your body needs all of
these things, and each is used differently.
How the body converts this fuel into energy is defined by
the concept of metabolism. “Energy
metabolism includes all the reactions by which the body obtains and expends
energy from food, (Whitney, 2011).” Although we are only discussing nutrition right
now and not exercise, it is important to consider the concept of metabolism
when designing a diet plan. We need to ensure that your diet contains the
correct quantity and balance of nutrients to sustain your body’s systems for
optimum health, but we also want to encourage your body to use its stored
energy (fat). There are two types of metabolic reactions. Anabolic reactions
are those in which simple compounds are used as building blocks to form larger,
more complex compounds, while catabolic reactions are those in which body
compounds are broken down to release the energy in their chemical bonds
(Whitney, 2011). These reactions take place primarily in your liver.
The amount of energy derived from a nutrient is expressed by
the term calorie. Many people are
confused by the concept of calories, but keep in mind that calories only
represent the amount of energy in the food, not the quality of nutrition. A
food could be high- or low-calorie
with a high- or low-quantity of
nutrients. The goal of balanced nutrition is to get enough nutrients without
eating too many calories (USDA, 2011). We can do this by eating foods that are nutrient-dense: this means they are high
in nutrients without being high in calories. If you do not consume the correct
balance of nutrients in your diet, then your body will signal you to continue
consuming, regardless of how much you actually eat. Additionally, if you
consume more nutrients than your body can use, your body stores the excess as
fat. Vitamins, minerals, and water do not contain any calories. However,
protein and carbohydrates each contain 4 calories per gram and lipids contain 9
calories per gram; it is on these macronutrients that we will focus, because
they make the “gasoline” that fuels the metabolism of your body. Each of these are converted into AcetylCoA
for energy (Whitney, 2011).
It is important to mention that losing weight is not as
simple as just cutting calories. Your body needs calories (remember, calories
are a measurement of energy, or fuel) to survive, and prolonged energy
restriction will effect negative consequences. To burn fat, we want to increase
your metabolism (the rate at which your body burns calories). One way to do
this is by building muscle. If you do not eat enough calories, your body will
actually slow down your metabolism in order to conserve energy for basic
necessary functions. Additionally, in a calorie-deficit situation, your body
will look to eliminate the most calorie-intensive tissue to maintain, which is
muscle. Therefore, if you restrict your intake of calories too much, your body
will conserve fat and burn muscle, which is the opposite effect you are trying
to achieve!
Additionally, overly restricting calories has a deleterious
effect on hormones and neurotransmitters in the body and brain. Your body slows
down production of thyroid hormones, testosterone, leptin, and serotonin, among
others. Serotonin is a neurotransmitter that regulates mood as well as appetite
and sleep. When you don’t eat enough, serotonin levels drop; this causes mood
swings and feelings of depression or even anger. "Changes in brain
chemistry that can affect your mood occur when you restrict calories,"
says Gary Wenk, PhD, in Your Brain on Food (Wenk, 2010). These unpleasant
feelings can contribute to emotional eating that can sabotage a healthy diet.
Decreasing thyroid levels also contribute to the slowing down of you
rmetabolism. When testosterone levels drop, it becomes difficult for the body to
maintain or grow muscle. Leptin is a hormone released from adipose (fat) tissue;
if leptin levels are too low, the brain receives the “I’m hungry” message to
consume more fuel (Marieb, 2010; Drent, 2007). All of these effects will hamper
your efforts to lose weight. Therefore, while the amount of calories you eat is important, focusing on the quality
of nutrients you are eating and not just on the number of calories will help
you achieve your goals.
So let’s discuss exactly how many calories you should be
eating, of what they should consist, and how they will react in your
metabolism. The USDA has set up daily nutrient recommendations based on the
Dietary Reference Intakes (DRIs) by age and gender (USDA, 2006) that will
define exactly how many grams of each nutrient you need to eat. Look at the interactive DRI to find out your recommended consumption based on your
age, height, weight, and gender: Interactive DRI (Enter your information and select "daily calorie needs".
For example, my results reccomend 2500 kCal (calories) a day. Based on Harvard’s “Healthy Eating Plate,” which is actually the best dietary recommendation available, we will increase the fiber to 35g since more of your foods will be coming from vegetables than from grains (Harvard, 2011). Let’s break down your plate contents by each macronutrient category.
o
Carbohydrates: 270 - 395 grams; 35 grams total
fiber
o
Lipids: 50 – 90 grams; 1.1 g alpha-linoleic acid
and 12g linoleic acid
Note: Saturated fats and trans-fats as close to 0g as possible.
o
Protein :
91 grams
As we stated earlier, carbohydrates have 4 calories per
gram; this means that 1080-1580 of my 2500 daily calories will be carbohydrates
like fruits, vegetables, and whole grains. Avoid starches like corn and
potatoes, and make sure you read the label on any bread you purchase to ensure
it’s really made from whole grain instead of processed white flour that’s been
“enriched” and dyed brown. Carbohydrates are polysaccharides, which are broken
down during digestion in the mouth, stomach, and small intestine into glucose
and other monosaccharides. Glucose, a six-carbon chain, is absorbed in the
small intestine and stored in the liver for future use in glycolysis. Glycolysis
is also known as anaerobic cellular
respiration, which is a way the body can synthesize energy, known as ATP,
without oxygen. Your body has to use some ATP to make ATP. Glucose is split
into smaller three-carbon compounds (Whitney, 2011). These compounds are able
to release 1ATP during a series of conversions, which also release 1 more ATP before
finally converting to pyruvate. During aerobic
cellular respiration, the body is able to most efficiently create ATP. In
the mitochondria of cells, pyruvate combines with the fatty acids derived from
lipids, the amino acids derived from proteins, and oxygen from respiration to
form ATP (Mareib, 2010). This is referred to as the Krebs cycle or the TCA
cycle. The by-products of this metabolism are water, which you excrete in
urine; carbon dioxide, which you exhale; and 32 ATP, which your body uses for
energy.
Your body gets 9 calories per gram from lipids; they are an
important source of fuel but not nutrient-dense. While they do not contribute
vitamins or minerals, the body has a vital need for unsaturated or
polyunsaturated lipids such as omega 3 fatty acids, linoleic acid, and alpha-linoleic acid. According
to the University of Maryland, “Alpha-linolenic acid is a kind of omega-3 fatty
acid found in plants. It is similar to the omega-3 fatty acids that are in fish
oil, called eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA),”
(Ehrlich, 2011). The body is able to convert alpha-linolenic acid into EPA and
DHA, which is especially important to note for vegetarian diets. Flaxseed oil, canola,
and walnut oils are good sources of alpha-linolenic acid, and linoleic acid is
easily obtained from olive oil, canola oil, and safflower oil. Ensure you
consume these essential fats for your 450-810 fat calories. In the liver, these
fats will be broken down into glycerol and fatty acids. During the process of
fatty acid oxidation, fatty chains (triglycerides, phospholipids, and
cholesterol), which typically have 16 or 18 carbons, are broken down 2 carbons
at a time into actylCoA for the TCA/Krebs energy cycle.
Proteins, with their 4 calories per gram, have been referred
to as “building blocks” because, literally, 50% of the dry weight of every cell
in the body is made of protein (Carter, 2004). The importance of protein is
that it contains amino acids, which, as you now know, are important in
metabolism. All amino acids feature a central carbon atom with a hydrogen atom,
an amino group, and an acid group; however, the type of “side chain” each has
for its fourth bond on the carbon atom is what differentiates them (Whitney,
2011). There are many different types of amino acids, but some of them must be
provided by the diet because they body cannot synthesize them. These are termed
“essential” amino acids. Most of these are available in animal proteins; some
vegetarians are deficit in the essential amino acid lysine and therefore take
supplements. The best sources for the essential amino acids in plant sources
are almonds, avocados, lentils, peanuts, mushrooms, whole grains, spinach,
green beans, and bananas (Geotextiles, 2013). Tryptophan, one of the
essentials, is also found in chocolate! If you are consuming a balanced,
nutrient-dense diet that contains enough essential amino acid-containing
protein, it is not necessary to take supplements, and you should use caution
and consult with a physician before taking any supplements. You may be surprised at how little protein you actually need...the myth of protein is part of why Americans have such a problem with obesity, cholesterol, heart disease, and kidney disease.
I have tried to explain a lot of complex biological
processes in a simplified way so that you can really understand your body’s
needs. I have avoided making specific meal plans because I think that it is
more beneficial for you to understand how the body works and in what foods you can find the elements it
needs. You can combine this knowledge with the Healthy Eating Plate
recommendations to plan your own meals day-to-day. I am always available should
you have further questions. I encourage you to consider adding 20 to 30 minutes
of exercise to your routine three times a week. This will enable you to build
more muscle and thus burn more fat. However, if you should substantially
increase your activity, we may need to revisit your caloric needs to ensure
proper nutrition. Please write to me if you need more help or resources.















