balanced diet Flashcards
food pyramid
- fats / oils, salt/sugar: eating too much may result in health problems
- dairy products: 2 glasses a day
- fish, meat, eggs, beans: 4-6 portions (one is the size of a ping pong ball)
- vegetables: at least 1.5 bowls of cooked vegetables a day
- fruits: at least 2 medium sized fruits a day (apple / orange)
- grains: 4-6 bowls a day
- fluids: 6-8 glasses a day
how is the energy value of food determined
mainly determined by the amounts of carbs / lipids / proteins
energy value of food substances
carbs: 17 kJ/g
lipids: 39 kJ/g
proteins: 18kJ/g
what should a balanced diet include
6 main types of food substances in the right amounts and proportions
comparing energy value of different snacks exp: iv / dv / cv
IV: type of snack
DV: energy value of snack (measured by the increase in temperature of water)
CV: mass of snack / volume of water
comparing energy value of different snacks exp: procedure
- fill a boiling tube with x cm3 of water
- use 2 stands and clamps to hold the thermometer extending into the boiling tube and the boiling tube
- measure and record temp of water
- measure and record the mass of the snack
- out the snack on a burning spoon and heat it in a bunsen flame
- when the snack starts to burn, quickly put the spoon under the boiling tube
- when the snack is completely burned, record the temp of the water in the table below
- repeat steps 4-7 with different snacks
comparing energy value of different snacks exp: sources of error
• heat loss to surroundings (heat energy from burning food may escape to surroundings
• incomplete combustion (some food may not burn completely -> not all energy is released)
• distance from bunsen flame -> heat loss
• heat absorption by the boiling tube
overall: low efficiency in heat transfer -> smaller increase in temp of water -> energy if food sample will be underestimated
comparing energy value of different snacks exp: improvements
• food samples can be crushed to increase the total surface area of the snack exposed to oxygen -> promotes combustion of snack, ensures complete combustion
• use a calorimeter to reduce heat loss to surroundings
• fix the distance between the burning food sample and the test tube
• insulate the test tube (eg. w wool) to reduce heat loss to surroundings
comparing energy value of different snacks exp: limitations
variation in water volume due to evaporation -> volume of water decreases over time leading to a higher increase in temp
what is overeating
taking in more energy than we need -> energy will not be used up, excess energy stored in body as fats -> increase in body mass (when energy input > energy output)
harms of obesity
being obese / overweight increases the risks of many health problems eg. high blood pressure / cardiovascular diseases / diabetes
harms of being underweight + diseases / disorders
being underweight may lead to health problems eg. poor growth, weak muscles and bones, and a weak immune system (may also suffer from deficiency diseases if our diet lacks certain food substances for a long time)
anorexia (eating disorder; leading to serious health problems and even death)
why does sleeping require energy
(breathing / cell growth + repair)
the more active we are, the more energy we require
why do males need more energy than females
as they have more muscles -> need more energy for muscle contraction
why does age group 15-18 need more energy
the most physically active / in final stages of growth -> need higher daily energy requirement
why does a breastfeeding mother need more energy
to create breastmilk with high energy and nutrient content
formula for BMI
body mass (kg) / height^2 (m^2)
for what people does BMI not apply to
doesn’t include muscular ppl (as muscles weigh more than fans) / elderly / pregnant women (extra weight)
bmi numbers
<18.5 underweight
18.5-22.9 normal
23.0-24.9 overweight
=>25.0 obese
what does the daily energy requirement of a person depends on
• age (children / teenagers need more energy as they are more active and are growing rapidly)
• gender
• activity level / occupation (ppl who do more physical work require more energy)
how may a vegetarian diet help ppl lose weight
diet mainly consists of vegetables -> rich in dietary fibre
consume large amount of dietary fibre:
• produce a sense of fullness easier -> lowers intake of food
• stimulate peristalsis -> less time for absorption of food
• decrease the surface area of ingested foods for enzymes to act on for digestion
• surface area of digested foods for absorption along the small intestine
energy inputs decrease -> may be lower than energy output
stored fat in the body will be broken down to release energy -> lose weight
how may a vegetarian diet NOT help ppl lose weight
• potatoes/grains/sweet potatoes are examples of vegetables that are rich in carbohydrates/ deep fried vegetables like potato chips are rich in fats
• carbs and fats contain a high energy content
• consuming a lot of such food can result in high energy input
• moreover, energy output does not change by consuming a vegetarian diet -> energy input may be =to or not< than energy output
no stored fats in the body are broken down to release energy, so there is no weight loss
