Food and Health (400:104)
Lecture 2 - January 24, 2011
ENERGY AND CALORIES
Lecture 2 - January 24, 2011
The Nutrients in Foods
• Nutrients: substances obtained
from food and used in the body
to promote growth,
maintenance, and repair.
• Essential nutrients: nutrients
that must be obtained from food
because the body cannot make
them for itself.
• Nonessential nutrients:
nutrients that the body needs,
but is able to make in sufficient
quantities when needed; do not
need to be obtained from food.
Department of Food Science
Lecture 2 - January 24, 2011
The Nutrients in Foods
• The energy-yielding nutrients:
– Carbohydrate
– Fat
– Protein
• Energy: the capacity to do work, such as moving or
heating something
– Calorie: the unit used to measure energy
• Alcohol also provides calories but it is a not considered a
nutrient because it is not needed to support life
Department of Food Science
Lecture 2 - January 24, 2011
Provide Energy?
-Carbohydrate
-Protein
-Fat
-Vitamins
-Minerals
-Water
Department of Food Science
•
•
•
•
•
•
YES
YES
YES
NO
NO
NO
The energyyielding nutrients
Lecture 2 - January 24, 2011
Energy Input
Energy: the capacity to do work, such as moving
or heating something
Calorie: the unit used to measure energy
– a kilocalorie is a unit of energy
– commonly used to express energy value of
food
Department of Food Science
Lecture 2 - January 24, 2011
Definition of calorie
(in Physics)
calorie: the amount of energy necessary to raise
the temperature of one gram of water by one
degree Celsius
In Nutrition one uses Calorie=kcal (1000 calories)
Department of Food Science
Lecture 2 - January 24, 2011
Department of Food Science
Lecture 2 - January 24, 2011
Calorie Values
Remember this
number…
Calorie value of carbohydrate, fat, and protein…
• If you know the number of grams of carbohydrate, fat, and
protein in a food, you can calculate the number of calories in it.
For example, a deluxe fast-food hamburger contains about 45
grams of carbohydrate, 39 grams of fat and 27 grams of protein
(see above).
Department of Food Science
Lecture 2 - January 24, 2011
Percentage of Total Energy Intake
The percentage of your total energy intake from
carbohydrate, fat, and protein can then be determined by
dividing the number of calories from each energy nutrient
by the total calories, and then multiplying the result by
100.
Department of Food Science
Lecture 2 - January 24, 2011
Calculating Energy Intake
Counting Calories
• If you know the approximate composition of the
foods you eat (% carb, pro, fat), and can
estimate the weight, you can calculate the
number of calories
• Use the food composition tables
• Use a diet analysis program
Department of Food Science
Lecture 2 - January 24, 2011
Calorie Calculation Exercise
Premium Crispy Chicken Ranch BLT Sandwich
Serving Size: 8.6 oz (245 g)
Medium French Fries
Serving Size: 4 oz (114 g)
Coca-Cola® Classic (Medium)
Serving Size: 21 fl. oz
Department of Food Science
Lecture 2 - January 24, 2011
Calorie Calculation Exercise
grams
FAT CARB PRO
Sandwich
(g)
(g)
Honey Wheat Roll
3
48
7
Crispy Chicken
9
13
19
Bacon
7
1
7
Ranch Sauce
2
2
0
Leaf Lettuce
0
0
0
Tomato Slice
0
1
0
16
47
4
0
58
0
Medium French Fries
Department of Food Science
(g)
Medium COKE
Lecture 2 - January 24, 2011
Calorie Calculation Exercise
CALORIES from:
Sandwich
Honey Wheat Roll
Crispy Chicken
Bacon
Ranch Sauce
Leaf Lettuce
Tomato Slice
Medium Fries
Medium COKE
Department of Food Science
FAT CARB PRO
Total
27
81
192
52
28
76
247
209
63
18
0
0
4
8
0
4
28
0
0
0
95
26
0
4
144
188
16
348
0
232
0
232
1161 kcal
Lecture 2 - January 24, 2011
Components of Energy Output
We Need Energy for:
• Basal Metabolism
– BMR = Basal Metabolic Rate
• Physical Activity
• Metabolizing Food
Department of Food Science
Lecture 2 - January 24, 2011
The ABCs of Eating for Health
Adequacy
getting all of the essential nutrients, fiber, and energy
(calories) in amounts sufficient to maintain health
Balance
eating foods rich in one nutrient while not crowding out foods
that are rich in another nutrient
Calorie control
control of energy consumption
Moderation
no unwanted constituent in excess
Variety
different foods, same purposes, different occasions
Department of Food Science
Lecture 2 - January 24, 2011
The ABCs of Eating for Health
Nutrient dense: refers to a food that supplies
large amounts of nutrients relative to the number
of calories it contains.
The higher the level of nutrients and the fewer the
number of calories, the more nutrient dense the
food
Department of Food Science
Lecture 2 - January 24, 2011
Department of Food Science
Lecture 2 - January 24, 2011
Department of Food Science
Lecture 2 - January 24, 2011
Department of Food Science
Lecture 2 - January 24, 2011
Nutrient Recommendations
• Dietary Reference Intakes (DRI): a set of reference values for
energy and nutrients that can be used for planning and assessing
diets for healthy people.
– Established by a committee of nutrition experts selected by
the National Academy of Sciences (NAS)
– Based on latest scientific evidence regarding diet and health
– The first set, called the Recommended Dietary Allowances
(RDA), was first published in 1943; revised ten times
– The series of DRI reports have been published since 1997
Department of Food Science
Lecture 2 - January 24, 2011
Dietary Reference Intakes
• DRIs have been developed for six nutrient groups:
– Calcium, phosphorus, magnesium, vitamin D and
fluoride
– B vitamins and choline
– Vitamin C, vitamin E, selenium and beta-carotene
– Energy and macronutrients
– Electrolytes and water
Department of Food Science
Copyright 2010, John Wiley & Sons, Inc.
Lecture 2 - January 24, 2011
Dietary Reference Intakes
• DRIs are designed for planning and assessing diets
of healthy people.
• Amounts recommended by DRIs are meant to
promote good health and reduce incidence of chronic
disease.
• The DRIs are not necessarily to be consumed every
day but should be consumed on most days, as an
average intake.
Department of Food Science
Copyright 2010, John Wiley & Sons, Inc.
Lecture 2 - January 24, 2011
Dietary Reference Intakes
(DRIs)
For micro- and macro-nutrients include:
-Estimated Average Requirement (EAR), used to
evaluate nutrient intake of populations
-Adequate Intakes (AI) recommend specific
amounts of nutrients for individuals
-RDAs (Recommended Daily Allowances)also
recommend specific amounts of nutrients for
individuals
-Tolerable Upper Intake Limit (UL) helps with the
prevention of nutrient toxicities
Department of Food Science
Lecture 2 - January 24, 2011
Reference Value Definitions
• Estimated Average Requirement (EAR)
– a daily nutrient intake value that is estimated to meet
the requirements of half the healthy individuals in a lifestage group (and same gender)
– intake at which the risk of inadequacy is 0.5 (50 percent)
to an individual
• Recommended Daily Allowance (RDA)
– the average daily intake level that is sufficient to meet
the nutrient requirement of nearly all (97-98%) healthy
individuals in a particular life stage and gender group
– the intake at which the risk of inadequacy is very small—
only 0.02 to 0.03 (2 to 3 percent)
Department of Food Science
Lecture 2 - January 24, 2011
Reference Value Definitions (cont.)
• Adequate intakes (AIs)
– Are not based on EAR values. Are used when there is
insufficient scientific evidences to set an EAR and
calculate the RDA
– It average nutrient intake by a healthy population. In
order to set an AI a criterion of adequacy must be
established.
• Tolerable Upper Limit (UL)
– highest level of a daily nutrient that is likely to pose no
risk of adverse health effects to almost all healthy
individuals
Department of Food Science
Lecture 2 - January 24, 2011
Reference Value Definitions (cont.)
• Tolerable upper intake level (UL): it is not
intended to be a recommended level of intake.
– The need for setting UL is the result of more
and more people using large doses of nutrient
supplements and the increasing availability of
fortified foods.
Department of Food Science
Lecture 2 - January 24, 2011
Setting DRIs
Risk of
Effects Due to
Deficiency
Risk of
Effects Due to
Toxicity
Consumed Amount
Department of Food Science
http://books.nap.edu/execsumm_pdf/6015.pdf
Lecture 2 - January 24, 2011
Setting DRIs
EAR:
50% risk of
inadequacy
RDA:
2-3% risk
of inadequacy
UL:
Upper Limit with no
risk of inadequacy
or adverse effects
Between RDA and UL:
Risk of inadequacy and of
excess are both close to 0
Department of Food Science
http://books.nap.edu/execsumm_pdf/6015.pdf
Lecture 2 - January 24, 2011
Setting DRIs
Goal for Daily
Intake of Individuals
Department of Food Science
http://books.nap.edu/execsumm_pdf/6015.pdf
Lecture 2 - January 24, 2011
The DRIs make two types of energy intake
recommendations:
• Estimated energy requirement: (EER): the average calorie
intake that is predicted to maintain energy balance in a
healthy adult of a defined age, gender, weight, height, and
level of physical activity, consistent with good health.
• Acceptable macronutrient distribution range (AMDR): a
range of intakes for a particular energy source
(carbohydrates, fat, protein) that is associated with a reduced
risk of chronic disease while providing adequate intakes of
essential nutrients. AMDR have also been set for specific
amino acids and fatty acids.
Department of Food Science
Lecture 2 - January 24, 2011
Recommended intake ranges
for energy nutrients
• Carbs
45 to 65% of total calories
• Fats
20 to 35% of total calories
• Proteins 10 to 35% of total calories
Department of Food Science
Lecture 2 - January 24, 2011
Why DRIs are improved over RDAs alone
• Reduction of risk of chronic disease is included in
recommendation, rather than just absence of signs of
deficiency
• Concepts of probability and risk used for determinations
• UL established where data for adverse effects exist
• Foods with composition containing ‘nutrient’ with possible
health benefit were reviewed and potential reference
intakes established
Department of Food Science
Lecture 2 - January 24, 2011
The Correct View of the DRI
Department of Food Science
Lecture 2 - January 24, 2011
Calories and Energy Balance – NOT
higher order math
Calories IN = Calories OUT
Calories IN > Calories OUT
Calories IN < Calories OUT
Maintain Weight
GAIN Weight
LOSE Weight
To maintain a desirable weight, energy
intakes should not exceed energy needs.
Department of Food Science
Lecture 2 - January 24, 2011
It’s all about Calorie Balance
• If you eat more calories than your body uses, they
will be stored as fat
• One pound (0.45 kg) of body fat is equal to
3,500 kcal
– In theory, losing one pound requires a deficit of 3,500
Calories
Eating 500 fewer Calories per day - or
expending 500 more Calories - would
result in losing one pound per week
Department of Food Science
Lecture 2 - January 24, 2011
REPEAT: Calorie Balance
Simple Math
No Loss or gain of weight occurs when:
Number of Calories Consumed EQUALS Number of
Calories Expended
1 POUND = 3500 Calories
If you eat 500 calories MORE than you expend, every
day for an entire week, you WILL gain
1 pound = 0.5 kg
Department of Food Science
Lecture 2 - January 24, 2011
Input &
Output
Example
A day in the life…
Intake:
3,400 kcal
Output:
3,005 kcal
650
50
270
100
Dressing/
50
Washing
Sitting in Class
Walking
to
Eating Breakfast 20 min.
180 min.
Campus
20 min.
20 min.
250
25
150
Walking on
Campus
30 min.
Snack
10 min.
At the Gym
40 min.
100
Library/Study
180 min.
75
Walking Home
Eating Dinner
20 min.
30 min.
180
105
25
Coffee Break
10 min.
700
395
1200
280
210
200
75
Walking to-from
Eating Lunch Campus
30 min.
30 min.
65
55
Check email
30 min.
390
400
50
Hanging out
490 Undress/Shower 260
with Date
Eating Snack
30 min
Emailing/Texting 120 min
20 min
Department of Food Science Sleep 71/2
Studying
120 min
hours
IMBALANCE:
395 kcal
Driving to-from
Date
30 min.
Dancing
40 min.
Lecture 2 - January 24, 2011
Weight Management
• To maintain body weight in a healthy range, balance
calories from foods and beverages with calories
expended
• To prevent gradual weight gain over time, make small
decreases in food and beverage calories and increase
physical activity
Department of Food Science
Lecture 2 - January 24, 2011
Energy Expenditure
• Calorie expenditure depends on:
– Weight of person
– Type of activity
• Length of activity
• Speed of activity
• Metabolic rate
From: Ainsworth, BE, et. al. 1993. Compendium of physical activities:
classification
ofFood
energy
costs of human physical activities. Medicine
Department of
Science
and Science in Sports and Exercise. 25 (1): 71-80.
Lecture 2 - January 24, 2011
How much exercise to offset breakfast?
1
Bagel with Cream Cheese
Coffee with Cream
125 pound (45kg woman)
=
309 Calories
32 Minutes Running a
10 Minute Mile=1.6 km
2
Dunkin Donuts Muffin
=
490 Calories
25 Minutes Swimming Laps
25 Minutes Cycling @ 15 mi/hr
Department of Food Science
Lecture 2 - January 24, 2011
How much exercise to cancel out lunch?
Turkey Sandwich
12 oz. Soda
1
1 oz. Potato Chips
125 pound (45kg woman)
=
585 Calories
9 Miles Walking Briskly
@13 min/mile
2
2 Slices of Cheese Pizza
=
366 Calories
1 Hour of Downhill Skiing
Department of Food Science
Lecture 2 - January 24, 2011
Dietary Guidelines for Americans
• The Dietary Guidelines for Americans is a set of diet and
lifestyle recommendations designed to promote health and
reduce chronic disease risks.
• Unlike the DRIs, which provide recommendations for
specific amounts of nutrients and food components, they
suggest overall diet and lifestyle that will promote health.
• 23 recommendations in 9 categories for all healthy
Americans 2 years+
• Get more nutrients in fewer calories, improve balance
between food intake and exercise, limit dietary
components that contribute to chronic diseases, keep
food safe
Department of Food Science
Copyright 2010, John Wiley & Sons, Inc.