A.2 Energy in Human Diets

IB Assessment Statement

• Compare the energy content per 100g of carbohydrate, fat, and protein.

Energy Content in Food

• Fats contain more than twice as much energy per 100 grams than carbohydrates and proteins

• Carbohydrates: 1,760 kJ per 100 g• Proteins: 1,720 kJ per 100 g• Fats: 4,000 kJ per 100 g

IB ASSESSMENT STATEMENT

• Compare the main dietary sources of energy in different ethnic groups.

Diet & Ethnicity

• Dietary energy can come from a range of sources (carbohydrates, proteins or fats), but for the bulk of the population, the primary source is crops cereals & grains.

• Most populations will supplement this with meat (primarily cattle in Western nations, chicken and fish in Eastern cultures)

• Independent island nations may rely on fish as their main dietary source of energy

Diet & Ethnicity

Diet & Ethnicity

IB Assessment Statement

• Explain the possible health consequences of diets rich in carbohydrates, fats, proteins.

Carbohydrates• Carbohydrates are broken

down into monosaccharide subunits for transport in the blood (blood sugar levels)

• A sustained high intake of carbohydrates may lead to the development of diabetes, as the liver becomes less sensitive to insulin

• Individuals with diabetes may experience more frequent urination (polyuria), increased thirst and dizziness

Protein• Excessive intake over a long period

of time may cause kidney problems– Deaminating (removing amine group)

proteins creates urea, and the kidneys will need to work overtime to flush out excess toxins, leading to damage over time.

• In eliminating our bodies of excess protein our kidneys use calcium, thus, if our kidneys can not find enough calcium they will leach it out of our bones, making our bone weaker.

Fats• Excessive fat intake is strongly

correlated to an increase in blood pressure, atherosclerosis and the incidence of coronary heart disease (CHD)

• Atheromas (fatty deposits) develop in the arteries and significantly reduce the diameter of the lumen of the artery wall needed for pulse flow

• This may lead to the formation of clots in the artery, and if this occurs in the coronary arteries it may lead to a heart attack and damage over time

IB Assessment Statement

• Outline the function of the appetite control center in the brain

A.2.4 Outline the function of the appetite control centre of the brain

• Appetite is controlled by hormones (leptin, insulin, CCK) produced in the pancreas, small intestine and adipose (fat) tissue

• These send messages to the appetite control center of the brain (hypothalamus), causing a person to feel that they have eaten enough (satiety)

• The release of hormones can be triggered in a number of ways:– Stretch receptors in the stomach lining may become activated

when the stomach is full– Adipose tissue may release hormones (leptin) in response to fat

storage

Ghrelin is released from cells in the GI Tract and there are receptors for ghrelin in the brain when you have not eaten in a while, and signals for you to feel hungry.

PYY 3-36 is released by the GI tract when you have eaten food .

Leptin is released from Fat tissue in body and signals for your body to not eat or signals for your body to feel satiated (full). It inhibits appetite.

VideosReading Food Labels:

– https://www.youtube.com/watch?v=yd9XnyNGXGsLow carb diet better than low fat diet

– https://www.youtube.com/watch?v=MX_eKKYvrqUUnderstand cholesterol and your heart

– https://www.youtube.com/watch?v=hjv5OnbcjE8Cardiovascular disease

– http://medmovie.com/library_id/3255/topic/ahaw_0070a/– http://medmovie.com/library_id/3255/topic/ahaw_0072a/

Obesity & Hunger are part of the same problem – Ted Talk– http://www.ted.com/talks/ellen_gustafson_obesity_hunger_1_global_food_issue?language=en

Obesity– https://www.youtube.com/watch?v=_X-5mk3BcfM (J. Olivier USA school lunches)– https://www.youtube.com/watch?v=LBko_3wT44Q (comedy)

Anorexia– https://www.youtube.com/watch?v=VS2mfWDryPE