Nutrition Taking care of your body by eating well and maintaining

a balanced diet is very important in order to keep fit, have more energy and be healthy.

Males generally have higher energy needs than females mainly because of differences in body size.

We need food to make energy (cellular respiration and the production of ATP). We also need food for the nutrients in order to grow, develop and rebuild cells

Vocab… Nutrient: any substance that has a useful function when

taken up by body cells. Joule: the unit used to measure energy. We still use the unit the calorie to measure energy in foods.

Calorie is actually a measurement of heat needed to increase the temperature of water by 1C.

All foods can be grouped into organic (produced by living things: carbohydrates, fats, proteins, vitamins) and inorganic (come from rock, soil, sea: minerals and water)

Chemical Reactions Your body performs many different

chemical reactions to stay alive. All of these grouped together are called your metabolism.

The breakdown of materials is called catabolism

The building of small molecules into larger ones is called anabolism

Metabolic Rate The rate at which the body converts stored

energy into working energy. Everybody’s metabolic rate is different

because it depends on a number of factors:Body size: larger burns more energyPhysical activity: more active, burn more

energyAge: decreases with ageHereditary factors: some have naturally higher.

Basal Metabolic Rate Is the amount of energy you would use per day if you

stayed in bed all day, with your body only performing vital processes.

BMR is accurately calculated by measuring the amount of oxygen used, but we can estimate using a formula:

Female BMR = [655 + (9.6 x mass in kg) + (1.8 x height in cm) - (4.7 x age in years)] x 4.18

Male BMR = [66 + (13.7 x mass in kg) + (5.0 x height in cm) - (6.8 x age in years)] x 4.18

BMR is measured in KJ (kilojoules)

Macronutrients Macronutrients are consumed in large amounts daily:

Carbohydrates: made of carbon, hydrogen and oxygen. major source of energy starch, sugar, cellulose provide glucose sources: cereals, breads, pasta, potatoes, rice, fruits, vegetables when too many carbs are taken in, stored as glycogen in liver and muscle cells, or as fat 3 main types: monosaccharides (simple sugars), disaccharides (lactose, sucrose), and

polysaccharides (starch, cellulose) Should make up 55% of your diet if healthy.

Carbohydrates

Macronutrients Continued Proteins: provide structure in the body

Some are enzymes, some are hormones, some act as cell surface markers that are targets for specific hormones, provide channels in the membrane of cells for transport.

Differ in size and shape and function Built from amino acids (joined together by peptide bonds)

We have 20 different amino acids and our body can make 12 of them, so there are another 8 that are essential for us to get from our foods.

Sources of protein: meat, fish, eggs, milk, cheese, beans, nuts, and lentils.

We need 60g of protein each day or 10%-30% of your energy requirement from protein.

Protein

Macronutrients Continued Fats: (or lipids) are a part of a balanced diet, in moderate

amounts. Lipids are used in various ways: Phopholipid bilayer in the cell membrane Cholesterol in the cell membrane Surround vital organs and joints protective cushion Surround nerves for fast signals Layer just underneath the skin provides insulation Concentrated source of energy Some are hormones (sex hormones) Linoleic, linolenic, and arachidonic are essential nutrients because

the body needs them and cannot make them from other substances

Fats and oils are made of 3 fatty acids bonded to a glycerol molecule to make a triglyceride

If fatty acid chains have multiple bonds, they are called unsaturated (oils)

If fatty acid chains have all single bonds, they are saturated fats (meat, butter)

Triglyceride

Micronutrients Micronutrients are vitamins and minerals that are taken in small

quantities. Vitamins are organic compounds that are vital to life.

Contain atoms of carbon, hydrogen, oxygen, nitrogen and some other elements.

Most vitamins act as coenzymes that join onto other enzymes to make sure reactions take place properly.

Can be divided into two types: Fat-soluble vitamins Water-soluble vitamins

Micronutrients Continued Minerals: important inorganic molecules.

Examples: iron (hemoglobin), calcium (nerve and muscle cells, bones and teeth, sodium (muscle, nerve cells), potassium (nerves, heart), and iodine (thyroid).

Water: not an energy source, but we cannot live without it. most of the weight of our bodies is from water plasma (blood) is more than 90% water sweat cools your body every time we breath out, some moisture is lost to the air, so it must be

replaced.

Fibre… Roughage is another important part of a complete diet. It

has no nutritional value, but aids in good digestion (dietary fibre)

Animals that eat a lot of plants, like rabbits, are able to break down the cellulose into a useful form due to the special bacterial flora in their large intestine.

Anorexia nervosa and bulimia Two different medical conditions that are categorized as

eating disorders. Exercise excessively or abuse laxatives. Bulimia is characterized by periods of binge eating, fasting,

and self-induced vomiting. Treatment is a very slow process of a combination of medical

and psychiatric interventions

Overeating

Obesity is sometimes caused by genetic factors Usually caused by inappropriate diet and inactivity. Percentage of overweight people is increasing in

Canada due to fast food and other sugary/high-fat foods.

Being overweight increases the risk of heart disease, respiratory problems, adult onset diabetes, cancer, high blood pressure, joint problems.