Ok. The first section of this Nutrition for dummies I looked at a rough overview of food. Now I'm going to break it down a little to look at the 3 Macro Nutrients ie the main body of our diet:
Protein
Fat, and
Carbohydrate.
We'll take them in that order, no particular reason, just cause!
Protein:
What it does - Protein is essential for a number of bodily functions, such as -
- it makes up many of the tissues in the body,
- it is essential for growth and repair
- it makes up many of the hormones (chemical messengers) as well as enzymes and antibodies
- Causes the release of the hormone Glucagon, which releases energy
What it is - Proteins are made up of chains of amino acids, and can be divided into complete or incomplete proteins depending on how many of the 8 essential amino acids they contain.
There are 20 amino acids, 8 of which are essential. Essential, in this context, means they are vital for health and cannot be synthesised from other foods. They are -
- Leucine
- Isoleucine
- Lysine
- Methionine
- Phenylalanine
- Threonine
- Tryptophan
- Valine
Non essential amino acids can be made up of combinations of other AAs that are plentiful and although incomplete proteins are lacking in 1 or more essential AAs, it is not always the same one that is missing. So by combining incomplete proteins in the correct combination, all the essential AAs can be consumed. Which is good news for any veggies out there, as most of the complete proteins are dead animal based! Soya beans and their products are complete proteins. Enjoy...
Protein requirements - Proteins are broken down into their component amino acids which make their way into the blood pool, and used as necessary. Since there is no long term storage area for protein that isn't in use, it must be consumed regularly in the correct amounts. Excess may be converted and stored as fat, but this doesn't happen as easily as for carbs and fat.
The average recommended protein intake is around 0.8g per kilogram of bodyweight.
Endurance athletes need between 1.2 and 1.4g/kg as energy production from protein rises from 5% at rest to around 15% after 1 hour, and although protein can't be used directly as fuel, conversion can occur when glucose stores are low.
Strength training requires around 1.4 - 1.8g/kg, and for muscle hypertrophy up to g/kg is recommended. (Timing is also important here, research shows that protein and carbs consumed within 30-60mins of training stimulates the release of insulin and growth hormone).
Fats
Fat is misunderstood. The general idea kicking about is that fat is bad. Fat is a killer. Don't eat fat.
Not true. Whilst excess fat is unhealthy,particularly saturated fat, fat is essential for your survival. Fats provide you with the highest energy vale of the 3 macro nutrients, 9kcals/g. It also:
- protects the organs
- helps with thermoregulation
- insulates the nerve cells (thereby allowing electrical impulses to pass between them)
- Allows the uptake and storage of fats soluble vitamins (A,D,E and K)
- Provides energy production
- aids in growth development and tissue repair (the cell membrane of every cell is a double layer of fat)
- and, in women, the storage and modification of reproductive hormones, particularly oestrogen.
This last point is important as in severe cases of low body fat %, ie anorexia, the reproductive cycle can cease all together. Also, as oestrogen promotes bone density and strength, a reduction in levels can have an affect on bone health.
How fat is made up - Fat is made up of carbon and hydrogen atoms and can be either saturated or unsaturated, depending on the formation of its carbon bonds. If each of the carbon atoms is holding as many hydrogen atoms as it can, it is said to be saturated. If, however, there is one or more carbon to carbon double bonds, these carbon atoms can't link to as many hydrogen atoms and therefore are unsaturated.
Saturated fats are generally found in animal products such butter, cream and the fatty layer that covers meat but also some non animal sources such as coconut and palm oil. Of all the fats, saturated are by far the most dangerous. The most notable effect of a diet high in saturated fat is an increased risk of chronic heart disease. This condition often leads to heart attacks and is by far the biggest killer in the United Kingdom. It appears to do this by increasing levels of low density lipoproteins ("bad" cholesterol) in the blood stream.
Because of the way they are built, saturated, mono-unsaturated and polyunsaturated fats all have different effects in the body. The most interesting difference is that unsaturated fats have no effect on cholesterol levels.
The easiest way to tell the difference between saturated and unsaturated fats is too look at them. Saturated animal fats, such as lard and butter are usually solid at room temperature. Unsaturated fats (monounsaturated and polyunsaturated), such as sunflower oil and olive oil, are usually liquid at room temperature.
Cholesterol is something for another post...
And finally, carbs...
The main role of carbohydrates in the body is the production of energy. Although most cells use a combination of fat and carbohydrates, the brain is only able to use carbohydrates. This is one reason people find it hard to cope on low carbohydrate diets, i.e. below 30% of calories consumed coming from carbohydrates.
All carbohydrates are formed from sugar molecules. How these sugars are linked and what types of sugars they are made up from will effect their taste, texture and effects on our bodies.
Carbohydrates can be divided into two groups: ·
SIMPLE carbohydrates (sugars), ie fruits, jams, sweets, and
COMPLEX carbohydrates (starches), ie bread, potato, pasta
Another form of carbohydrate is fibre, the indigestible parts of starch found in - vegetables, fruits (canned,fresh or dried) and grains.
Refined carbohydrates have had many of their original properties removed and manufactured elements added such as colourings and preservatives. This makes them a good source of energy, but lacking in dietary fibre, vitamins and minerals and produces a faster insulin response. In other words, they taste good but generally suck.
Refined carbohydrates include:
- White bread, rice and pasta
- Cakes bisuits and pastries
- CHO content in processed food
Unrefined carbohydrates have had little alterations made to them. They are natural products with little or no interventions. This makes them a good source of energy but also a good source of dietary fibre, vitamins and minerals and they give a slower, sustained insulin response. Unrefined carbohydrates include:Wholemeal and whole grain products
- Fresh and frozen vegetables
As with proteins, to be used in the body, carbohydrates must be broken into single molecules, such as glucose, fructose or galactose.
When glucose enters the blood stream, one of three things generally happens:
1. It can travel around in the blood providing energy to any cells that need it, hence the name, blood sugar.
2. If blood sugar levels are high enough, glucose can be converted to glycogen, which is stored in the muscles and liver. The body can store an average of 500g of glycogen at any one time. About 400g in the muscles and 100g in the liver.
3. If both blood sugar and glycogen levels are high, glucose can be converted and stored as body fat. The bad news is that fat cells have an almost limitless storage capacity, they can swell to 1000 times their size and then, if need be, divide in two!
From here I could go on and on and on about the many other factors involved in nutrition. As I've already mentioned, cholesterol is for another day, as is insulin response to food, glucagon, cortisol and the various other hormonal responses to what you eat and how it affects you.
This was just an overview of the basics. If you want to know more, here are some great rresources for you to check out...
Precision nutrition - Dr John Berardi goes in depth into every aspect of nutrition
Leigh Peele - Leigh has a load of great content based on in depth research
Mark Bittman - Columnist for the Ny Times, some of it is U.S. based but all interesting stuff.
Alan Aragon - Alans' Research Review has a load of great info, it is subscription based, but his free articles are great too.
Hope everyone has a great week, whats left of it!
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