MACRONUTRIENTS

During digestion, foods that contain carbohydrates are converted into glucose.                Most of this glucose is sent into your bloodstream, causing a rise in blood glucose levels. 

GLUCOSE: comes from the Greek word for "sweet." It's a type of sugar you get from foods you eat, and your body uses it for energy.

Glycogenesis, the formation of glycogen, the primary carbohydrate stored in the liver and muscle cells of animals, from glucose and is stimulated by the hormone INSULIN. (ANABOLIC RXN)

Glycogenesis takes place when blood glucose levels are sufficiently high to allow excess glucose to be stored in liver and muscle cells. 

Glycogenolysis is the break down of glycogen into glucose-1-phosphate and glycogen. (CATABOLIC RXN)

Glucogenolysis in the absence of carbohydrate (during fast), liver glycogen is an important source of glucose to meet the tissue needs for 10-18 hours. (ANABOLIC RXN)

During prolonged fasting, liver glycogen stores are depleted, and glucose is formed by gluconeogenesis. (Gluco- : glucose, neo-: new, genesis: make or create).

CARBOHYDRATE STRUCTURE

MONOSACCHARIDES- one molecule

DISACCHARIDES- 2 monosaccharides

COMPLEX CARBOHYDRATES: more than 2 sugar molecules

WHEN YOU EAT, SUGAR GOES INTO YOUR BLOOD:

There are two types of diabetes:

• In type 1 diabetes, your body doesn't have enough insulin. The immune system attacks and destroys cells of the pancreas, where insulin is made.
• In type 2 diabetes, the cells don't respond to insulin like they should. So the pancreas needs to make more and more insulin to move glucose into the cells. Eventually, the pancreas is damaged and can't make enough insulin to meet the body's needs.

Without enough insulin, glucose can't move into the cells. The blood glucose level stays high. A level over 200 mg/dl 2 hours after a meal or over 125 mg/dl fasting is high blood glucose, called hyperglycemia.

What is Glucagon and how does it work?

Glucagon works to counterbalance the actions of insulin. It is a hormone formed in the pancreas which promotes the breakdown of glycogen to glucose in the liver.

After you have eaten the glucose levels in your blood decrease, triggering your pancreas to produce glucagon. 

• This hormone signals your liver and muscle cells to change the stored glycogen back into glucose. 
• These cells then release the glucose into your bloodstream so your other cells can use it for energy.

This whole feedback loop with insulin and glucagon is constantly in motion. 

It keeps your blood sugar levels from dipping too low, ensuring that your body has a steady supply of energy.

Too much blood sugar can cause damage to organs, blood vessels, and nerves. Your body also needs insulin in order to use sugar for energy.

Eleven million Canadians are living with diabetes or prediabetes. Chances are, diabetes affects you or someone you know.

NOTE ABOUT CARBOHYDRATES & PROTEIN 

Going without eating carbs for an extended amount of time or CUTTING CARBS will deplete your GLYCOGEN STORES. 

Your body NEEDS FUEL so it will grab protein from your diet (if available), skeletal muscles and organs and convert its amino acids into glucose (gluconeogenesis) for energy and to maintain normal blood glucose levels. 

This can cause muscle loss, problems with immunity and other functions of proteins in the body. This is why you will see people who restrict their 'diets' lose muscle mass instead of the desired adipose tissue.

PROTEINS

PROTEINS:

Their building blocks are nitrogen-containing molecules called AMINO ACIDS. There are 20 different types of amino acids that can be combined to make a protein. Proteins are polymers, meaning they are large molecules made up of many smaller molecules. 

The small molecules that make up proteins are called amino acids.

Proteins have a wide range of functions in the body which can be summarized in four functional groups: 

• Structural muscles, bones, skin, cells
• Transport/communication plasma proteins, hormones, receptors, neurotransmitters
• Protective antibodies, mucus, anti-inflammatory proteins 
• Enzymatic digestion, metabolic pathways, O2 and CO2 transport

PROTEINS ARE BUILDING BLOCKS!

Provides your body with 4 kcals per gram

Proteins help keep fluids and acids in balance; they transport oxygen to your cells; act as antibodies, enzymes, and hormones; and feed vitamins and minerals to your cells. They work as the maintenance crew on tissues such as blood vessels. Other proteins take your body's energy and use it contract your muscles and divide cells.

The proteins that facilitate chemical reactions are called enzymes (proenzymes in their inactive state). Proteins also carry messages throughout the body. Hormones such as insulin, for example, regulate blood glucose levels.

Protein molecules also form the antibodies that fight infection due to virus or bacteria. At the same time, they help your body maintain proper fluid balance between its three fluid compartments:

• Intracellular, or within the cells
• Intravascular, or within the blood
• Extracellular, or outside the cells 
  

Unlike fat and carbohydrate there is no storage capacity for protein in the body. 

All protein is present with a specific biological function (e.g. as enzymes or structural proteins such as muscle). All protein molecules are constantly being broken down into their constituent amino acids and resynthesized. 

The steady loss of amino acids from the body along with no storage means that a regular daily intake of protein is required to sustain biological function and health. 

The current level of intake recommended for healthy adults is 0.8 grams per kilogram of body mass per day 

What Are Proteins Made Of?

Proteins are polymers, meaning they are large molecules made up of many smaller molecules. The small molecules that make up proteins are called amino acids.

Each amino acid contains a carbon atom, an amino group, a carboxyl group, and a side chain (also known as an R group).

This is the basic structure of an amino acid. On the left is an amine, a nitrogen atom with two hydrogen atoms. 

On the right is a carboxyl, a carbon atom with two oxygen atoms and a hydrogen. 

In the centre is the "R" group, a part of the molecule that is different for every type of amino acid. 

Different Types of Protein Structure

The structure of proteins is directly related to their function and may be primary, secondary, tertiary, or quaternary.

One example of a quaternary protein structure is hemoglobin.                                          Hemoglobin is made up of four polypeptide chains, and is specially adapted to bind oxygen in the blood. REMEMBER THIS ONE FOR GAS EXCHANGE

What Are Essential Amino Acids?

There are two types of amino acids: essential and nonessential. The human body does not produce these proteins, even though they are vital to sustain human life. This means you must get them in the protein found in plant and animal food sources.

The eight essential amino acids are:

• Isoleucine
• Leucine
• Lysine
• Methionine
• Phenylalanine
• Threonine
• Tryptophan
• Valine

What Are Nonessential Amino Acids?

Your body naturally produces the nonessential amino acids. When you enjoy good health, your body's production is enough to maintain homeostasis (that is, a constant state). However, illness and stress, as well as a diet low in the essential amino acids, inhibit your body's ability to produce adequate amounts of nonessential amino acids.

The nonessential amino acids include:

• Alanine
• Arginine
• Asparagine
• Aspartic acid
• Cysteine
• Glutamic acid
• Glutamine
• Glycine
• Proline
• Serine
• Tyrosine

Classes of Protein Structure

The function of a protein depends heavily on its final structure. Tertiary and quaternary proteins are both functional proteins with a 3D structure. However, the type of structure can vary significantly between different proteins. There are two main classes of 3D protein structure: globular proteins and fibrous proteins.

Globular Proteins

Globular proteins are usually round and ball-shaped. They usually have metabolic functions, for example, they may be enzymes or antibodies. Hemoglobin is an example of a globular protein.

Fibrous Proteins

Fibrous proteins are long and narrow and usually have a structural function. Examples of fibrous proteins include collagen (found in bones, muscle, and skin) and keratin (the material that makes up hair, nails, and feathers).

Proteins are only functional so long as they keep their 3D structure.                                          If they are unfolded and lose their shape, they will no longer be functional. 

This may happen if the protein is put under stress, for example by heating, changes in pH, dehydration, or vigorous shaking. The protein may be able to return to its original shape once the denaturing agent is removed but, in some cases, denaturation is permanent.

LIPIDS

FATS:

Fats are NOT WATER SOLUABLE. Fat digestion is a complex process that takes time and requires a functioning liver, pancreas, stomach, and small intestine, as well as numerous digestive enzymes. Dietary fats are essential to give your body energy and to support cell function. They also help protect your organs and help keep your body warm. Fats help your body absorb some nutrients and produce important hormones, too. 

Provides your body with 9 kcals per gram

Your liver produces bile that helps you digest fats and certain vitamins. 

This bile is stored in the gallbladder. These digestive juices are delivered to your small intestine through ducts where it all works together to complete the fat breakdown. 

FATTY ACIDS

When we eat fats in our foods, our bodies break them back down into fatty acids. Fatty acids are the building blocks of our cell membranes, and they are part of every cell in our bodies!

There are the non-essential and essential fats, (omega 3s and omega 6s).                          The body can't produce ESSENTIAL fats. Therefore, we need to get omega 3s or omega 6s from dietary sources. 

Fatty acids are a chain of carbon atoms with hydrogen attached, and a methyl group (CH3) and a carboxyl group (COOH) on each end.

There are different kinds with different structures.  

• Saturated fatty acids (SFA) with the maximal number of hydrogen atoms (four) on each carbon atom. 
• Unsaturated fatty acids where two hydrogen atoms are missing form double bonds between two carbon atoms and become unsaturated. 
• Monounsaturated fatty acids (MUFA) with a single double bond in the chain. 
• Polyunsaturated fatty acids (PUFA) shaped by multiple double bonds. 

Unsaturated fats

Unsaturated fats, which are liquid at room temperature, are considered beneficial fats because they can improve blood cholesterol levels, ease inflammation, stabilize heart rhythms, and play a number of other beneficial roles. Unsaturated fats are predominantly found in foods from plants, such as vegetable oils, nuts, and seeds.

There are two types of "good" unsaturated fats:

1. Monounsaturated fats are found in high concentrations in:

• • Olive, peanut, and canola oils
  • Avocados
  • Nuts such as almonds, hazelnuts, and pecans
  • Seeds such as pumpkin and sesame seeds

2. Polyunsaturated fats are found in high concentrations in

• • Sunflower, corn, soybean, and flaxseed oils
  • Walnuts
  • Flax seeds
  • Fish
  • Canola oil - though higher in monounsaturated fat, it's also a good source of polyunsaturated fat.

Saturated Fats

All foods containing fat have a mix of specific types of fats. Even healthy foods like chicken and nuts have small amounts of saturated fat, though much less than the amounts found in beef, cheese, and ice cream. Saturated fat is mainly found in animal foods, but a few plant foods are also high in saturated fats, such as coconut, coconut oil, palm oil, and palm kernel oil.

• The Dietary Guidelines for Americans recommends getting less than 10 percent of calories each day from saturated fat.
• The American Heart Association goes even further, recommending limiting saturated fat to no more than 7 percent of calories.
• Cutting back on saturated fat will likely have no benefit, however, if people replace saturated fat with refined carbohydrates. Eating refined carbohydrates in place of saturated fat does lower "bad" LDL cholesterol, but it also lowers the "good" HDL cholesterol and increases triglycerides. The net effect is as bad for the heart as eating too much saturated fat.

In the North America, the biggest sources of saturated fat in the diet are:

• Pizza and cheese
• Whole and reduced fat milk, butter and dairy desserts
• Meat products (sausage, bacon, beef, hamburgers)
• Cookies and other grain-based desserts
• A variety of mixed fast food dishes

Trans Fats

Trans fatty acids, more commonly called trans fats. Trans fatty acids are not found naturally in foods, but instead are a result of an industrial process called hydrogenation. Trans fatty acids are formed when manufacturers turn liquid oils into solid fats. Vegetable oils are converted to solid fats simply by adding hydrogen atoms.                                                                          Example shortening and hard margarine

• Partially hydrogenating vegetable oils makes them more stable and less likely to become rancid. This process also converts the oil into a solid, which makes them function as margarine or shortening.

• Partially hydrogenated oils can withstand repeated heating without breaking down, making them ideal for frying fast foods.
• For these reasons, partially hydrogenated oils became a mainstay in restaurants and the food industry - for frying, baked goods, and processed snack foods and margarine.

Partially hydrogenated oil is not the only source of trans fats in our diets. Trans fats are also naturally found in beef fat and dairy fat in small amounts.

Trans fats are the worst type of fat for the heart, blood vessels, and rest of the body because they:

• Raise bad LDL and lower good HDL
• Create inflammation - a reaction related to immunity - which has been implicated in heart disease, stroke, diabetes, and other chronic conditions
• Contribute to insulin resistance
• Can have harmful health effects even in small amounts - for each additional 2 percent of calories from trans fat consumed daily, the risk of coronary heart disease increases by 23 percent

HarvardChanSPH-https://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/fats-and-cholesterol/types-of-fat/

  

Triglycerides and Cholesterol both belong to the "fat family" 

Triglycerides are the most common type of fat in the body.  This is stored in the body's fat cells. When you eat more calories than you need, the body stores those calories in the form of triglycerides, which can be used later by the body for energy. 

Cholesterol

Cholesterol is a fatty substance found in your blood. and is produced naturally in the liver. Everyone has cholesterol. 

We need it to stay healthy because every cell in our body uses it. Some of this cholesterol comes from the food we eat Cholesterol comes from the food you eat, and your liver makes more. It won't dissolve in blood, so proteins carry it where it needs to go. These carriers are called lipoproteins. 

GOOD CHOLESTEROL HDL

HDL takes cholesterol that you don't need back to the liver. The liver breaks it down so it can be passed out of your body.  

HDL is increased through EXERCISE

LDL is the bad cholesterol and it becomes attached to artery walls, which promotes atherosclerosis (narrowing of arteries and cardiovascular disease), which is then manifested as high blood pressure, heart disease and strokes.

Ways of lowering LDL is by exercise and diet modification

VLDL contains more triglycerides. LDL contains more cholesterol. VLDL and LDL are both considered types of "bad" cholesterol. 

You can have a normal level of HDL and non-HDL cholesterol but still have a high triglyceride level.

The intake of 100 grams of fat provides 4000kJ; about three times more than carbohydrates and proteins! 

 Fats CANNOT be used to produce energy Anaerobically