lesson 14.1 thebasics of...

Lesson 14.1

© 2015 Thompson Educational Publishing, Inc. 1

THE BASICS OF SPORT NUTRITION

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TOPICS COVERED IN THIS LESSON

• (a) Macronutrients and Micronutrients

• (b) Dietary Fats: The Good and the Bad

Nutrients


The foods we eat are made up of differentcomponents that we call nutrients. These nutrientsare divided into two categories:

• Macronutrients make up the largest part of the food we eat

and supply us with the energy we need for daily life and forphysical exercise.

• Micronutrients are found in small amounts in food. They

include vitamins and minerals, which help in energy transfer

and tissue synthesis.

Carbohydrates, Proteins, and Fats

Macronutrients are the human body’s direct sources of energy: carbohydrates, proteins, andfats. Macronutrients supply us with the energywe need for daily life and for physical exercise.

• Carbohydrates—4Calories per gram

(kilocalories)

• Protein—4 Calories per

gram (kilocalories)

• Fat—9 Calories per

gram (kilocalories)


Vitamins and Minerals


Micronutrients act as co-agents in the bioenergetic process. They do not provide energy themselves but rather play an indispensable role in helping the body’s metabolic processes along.

• Vitamins help to regulate metabolic reactions in

the body, in contrast to other dietary components

(e.g., fats, carbohydrates, and proteins), which are

utilized in the reactions.

• Minerals (such as iron) are inorganic substances

needed by the body for good health. Besides

helping the body get energy from macronutrients, minerals help produce bones, proteins, and blood.

Classifying Carbohydrates (“Carbs”)


Carbohydrates are divided into two maintypes: simple (sugars) and complex(starches).

• Simple carbohydrates are digested and

absorbed much more rapidly than complex

carbohydrates and can cause large swings in

our blood sugar levels. Foods that contain

simple carbohydrates include table sugar, soft

drinks, fruit juices, honey, processed foods,

and junk foods.

• Complex carbohydrates are digested and

absorbed more slowly than simple

carbohydrates. As an added benefit, foods

containing complex carbohydrates often containmany of the vitamins, minerals, proteins, and

fibre that our bodies need.

The Glycemic Index


The blood sugar (or blood glucose) level refers to the concentration of glucose (sugar) presentin the blood. The body tightly regulates bloodglucose levels.

• The glycemic index is a measure that we can

use to help us understand how foods will affect

our blood sugar when we eat them.

• This index indicates the rate of carbohydrate

digestion and its effects on blood glucose levels.

“Empty Calories”

Refined sugars provide calories, but lack vitamins, minerals, and fibre. For this reason, they are often called “empty calories.”

• The extra calories are converted to fat and stored

in the body as fat tissue.

• Complex carbohydrates, such as fruits, grains, andvegetables, are considerably better for us.


Proteins: Essential “Building Blocks”


Proteins are molecules that make up a large portion of our body and they are involved in virtually all of our body’s cellular functions.They are essential nutrients and the building blocks of body tissue.

• The average adult body consists of 10 to 12 kg of

proteins, which are mostly found in our muscles.

• Proteins are directly involved in the fundamental

chemical processes of life and they play important

roles in how our bodies move and function.

• Proteins can also serve as a fuel source

(4 kilocalories per gram).

Amino Acids


Proteins are species-specific and organ-specific(i.e., within a single organism, muscle proteinsdiffer from those of the brain or liver).

When we eat foods that contain proteins, the body digests them and breaks them down into individual amino acids or small clusters of amino acids known as peptides.

• Amino acids are the building blocks of proteins.Twenty different amino acids are used to create

the more than 50,000 proteins found in the body.

• Nine of these amino acids must be supplied by thefoods we eat—these are “essential amino acids.”

Our bodies can produce the other 11 amino acids—

these are “non-essential amino acids.”

Daily Protein Requirements

Daily protein requirements differ from individualto individual, depending on the energy demandsplaced on each person’s body.


Dietary Fat: The Good and the Bad

Dietary fat is important for our overall health, but some types of fat should be limited.

There are four types of fat, in two broad groups:

• Unsaturated Fats:

Mono-unsaturated

and polyunsaturatedfats (the so-called

“good” fats), and

• Saturated Fats:

Saturated and trans

fats (the “bad” fats).


The Unhealthiest Fat of All

Nutritionists all agree that the worst type of dietary fat is the kind known as trans fat.

• Trans fat results from

a process called “hydrogenation.”

• This process turns

oils into solids. It alsomakes healthy vegetable

oils behave more like

saturated fats.

• On food label ingredient

lists, this manufactured

substance is often listed, somewhat

innocuously, as “partially

hydrogenated oil.”


Staving off Heart Disease


Diets high in saturated fats have been linked to heart disease and vascular disease, leading to increased risk of heart attacks and strokes.

• Diets rich in unsaturated fats are not believed to

increase the risk of heart and vascular disease,

as there appears to be less fat deposited in the coronary arteries.

• Nutrition experts now recommend that we replace

saturated fats (and trans fats) in our diet with mono- and polyunsaturated fats.

Lesson 14.1


SUMMARY

• Nutrients are divided into two categories:

macronutrients (carbohydrates, protein, and fats)

and micronutrients (vitamins and minerals).

• Carbohydrates are also divided into two main

types: simple (sugars) and complex (starches).

• Refined sugars provide calories, but lack vitamins, minerals, and fibre.

• Proteins are directly involved in the fundamental

chemical processes of life.

• There are four types of fat, in two broad groups:

mono-unsaturated and polyunsaturated fats (the

so-called unsaturated “good” fats) and saturated

and trans fats (the saturated “bad” fats).

Promoting Canadians’ Nutritional Health

The federal departmentresponsible for helping Canadians maintain and improve their health isHealth Canada.

• Canada’s first food guide,

the Official Food Rules, wasintroduced to the public in July

1942.

• Since 1942, the food guide has been transformed many times,

yet has never wavered from its

original purpose of guiding food selection and promoting the

nutritional health of Canadians.

Photo: Canada Food Guide, 1949 Version.


Canada’s Food Guide

The food intake pattern recommended in themost recent Canada’s Food Guide is based oncurrent nutritional science.


Preventing Nutrient Deficiencies


Since 1938, Health Canada has providedrecommendations as to how much of each nutrient we need to take in every day to stay healthy.

• Dietary Reference Intakes (DRIs) are based

on the amount of nutrients needed to prevent

deficiencies.

• A nutrient deficiency develops when we do not

get enough nutrients for proper growth and good

health—for example, people can develop a disease called scurvy if they do not get enough vitamin C.

Be Wary of Nutrient Content Claims


Manufacturers are permitted to use nutrient content claims, such as those below, to attractattention to their products.

• Fat-free foods. Often foods that are fat free

contain a large number of calories due to increased amounts of sugars and carbohydrates

added to improve the flavour.

• Low-fat foods. Low-fat foods often contain a high

simple sugar content. The result is that people may

not actually be consuming less energy, which is

what determines weight gain (in the absence of exercise).

• Light foods. Consumers must read food labels

carefully to understand exactly how much energyis contained in the food item.

Nutrition Facts Tables on Food Products


A Nutrition Facts table appears in a standardformat on food product labels.

• The Nutrition Facts table is intended to present

nutritional information in basically the sameformat from one product to another.

• The main (core) ingredients are listed in the table.

• The same 13 core nutrients are always listed in the same order.

A Nutrition Facts Table’s Standard Format


The Portion (Serving) Size of a Food Item


Total Calories and 13 Core Nutrients


The Actual Amounts of Nutrients


What Exactly is “% Daily Value”?


The % Daily Value column of the Nutrition Factstable is based on the recommended intakes foreach nutrient each day.

• The value in this column indicates the percentage

of your daily recommended intake that you will

receive from this portion size.

• You can use the % Daily Value information in this

column to identify the strengths and weaknesses

of a particular food product and whether it is suitable for you.

• Note that the % Daily Value is based on an

(average) 2000 Calorie per day diet, and so may vary from individual to individual.

% Daily Value on a Sample Product Label


Serving Size Matters


When reading labels, be especially vigilant when it comesto serving sizes.

• Serving sizes are determined by the food manufacturer and are

sometimes very small compared to what people normally

consume.

• Therefore, make sure you read the label carefully to see how big theserving size is, so that you can better understand the nutritional

information on the label.

Lesson 14.2


SUMMARY

• Health Canada’s Dietary Reference Intakes (DRIs)

are based on the amount of nutrients needed to

prevent deficiencies.

• The same 13 core nutrients are always listed in

the same order on Nutrition Facts tables.

• Manufacturers are permitted to use nutrient content claims on food packaging, so it is

important to know what such claims mean.

• The % Daily Value column of the Nutrition Facts

table is based on the recommended intakes for

each nutrient each day.

• When reading labels, be especially vigilant when it

comes to serving sizes.

Energy Balance and Body Weight


The principle underlying eating well in order to maintain a healthy body weight is one of balance.

• Stated simply, the energy (food) we take in each

day should closely match the effort (energy

output) we expend.

• To some extent, this balance is specific to the

individual at any given point in time.

The Energy Equation


This basic “energy in, energy out” relationship can be expressed in the form of a simple equation:

Energy storage = Energy intake – Energy output

• In other words, the amount of excess energy

stored by our body is the difference between the amount of energy taken in and the amount of

energy expended.

The Energy Equation


What is a Food Calorie?


A calorie is the amount of energy needed toraise the temperature of 1 gram of pure water by 1°C.

• In a dietary context, what we call a calorie (or

a food calorie) is, in fact, a kilocalorie (1000

calories).

• Calories are a measure of the amount of energy

that food will produce as it is processed by the

body.

Energy Nutrients and Calories


The three energy nutrients in food supply calories in different amounts:

• 1 gram of carbohydrate provides 4 calories

• 1 gram of protein provides 4 calories

• 1 gram of fat provides 9 calories

Daily Caloric Need


The concept of daily caloric need refers to the amount of calories each of us needs in order to maintain an “energy balance” and, thus, our current body weight.

Our daily caloric need is shaped by:

• Basal metabolic rate (the amount of energy we

need to keep our bodies functioning)

• The calories needed to fuel activity, according toour specific activity level; and

• The energy needed to digest, absorb, transport,

and store the food we ingest.

How Many Calories Are Enough, But Not Too Many?


Each person’s energy needs are different.

• A football lineman needs to take in more calories

than an inactive person; a young person, more

calories than an older person, and so on.

• Nutritionists generally recommend that we get 45

to 65 percent of our calories from carbohydrates,

10 to 35 percent from protein, and 20 to 35

percent from fat.

• However, again, proportions can vary. Top-level

athletes’ energy needs can vary significantly from

those of an active person, depending on the needs

of their sport.

Sustaining Bodily Functions


The energy that needs to be consumed in order to sustain essential bodily functions is knownas one’s metabolic rate (MR).

• Bodily functions include such things as heartbeat,

breathing, nervous system activity, active

transport, and secretion.

• Age, gender, weight, lean muscle mass, and

general level of physical fitness affect your

metabolic rate.

Basal and Resting Metabolic Rate


Two terms are used, sometimes interchangeably, to refer to metabolic rate.

• Basal metabolic rate (BMR) is the term used

when MR is measured using rigorous (laboratory)

conditions, typically 12 to 14 hours after the last

meal, with the individual completely at rest (but not asleep), and a background temperature of 26

to 30°C.

• Resting metabolic rate (RMR) is the term used

to refer to an estimate of metabolic rate under less

rigorous conditions.

The Harris-Benedict Equation


The Harris-Benedict equation, dating back to 1918, is still widely used to arrive at areasonably accurate estimate of RMR. Theformula varies slightly for males and females:

• MalesRMR = 66.5 + (5 x H) + (12.7 x W) - (6.8 x A)

• FemalesRMR = 66.5 + (1.9 x H) + (9.5 x W) - (4.7 x A)

In this equation, W equals a person’s weight in kilograms; H equals height in centimetres; and A equals age in years. The result can then be multiplied by an “activity factor” to arrive at one’s daily caloric need.

A Quick Method for Calculating Daily Caloric Need


There is an easier way to calculate daily caloric need: First, roughly estimate your RMR—adult males can multiply their weight in kilograms by24.2; adult females can multiply their weightin kilograms by 22.0. This RMR figure can then be multiplied by an “activity factor” to estimateyour daily caloric need requirements. Forexample:

• A person who is relatively sedentary could

multiply his or her RMR by a factor of 1.4.

• A person who is relatively active could multiply his

or her RMR by a factor of 1.6.

• A person who is highly active could multiply RMR

by a factor of 1.8.

Health Canada’s Daily RecommendedCalorie Intake at Varying Activity Levels


Lesson 14.3


SUMMARY

• In a dietary context, what we call a calorie (food

calorie) is, in fact, a kilocalorie (1000 calories).

• The three energy nutrients in food supply caloriesin different amounts:

• 1 gram of carbohydrate provides 4 calories

• 1 gram of protein provides 4 calories

• 1 gram of fat provides 9 calories

• Daily caloric need (DCN) is the amount of calorieswe need to maintain an “energy balance.”

• The Harris-Benedict equation, dating back to 1918,

can provide an accurate estimate of resting

metabolic rate. From this, one can estimate one’s

daily caloric need, based on one’s level of activity.

Body Mass Index (BMI)


BMI is widely used to assess the extent to which individuals are underweight oroverweight. It is calculated as the ratio of a person’s weight to the square of his or her height:

BMI = WEIGHT (KG) / HEIGHT (M2)

Generally:

• People with a BMI of 25 to 30 are considered to be

overweight.

• Those with a BMI score of 30 or more areconsidered obese.

• Individuals with a BMI of 18.5 or lower are

considered to be underweight.

What’s Flawed About the BMI Index?


BMI is used worldwide to estimate body weight and to make comparisons across populationgroups.

• The main reason for this widespread use is that

BMI is easy to measure and to compute.

• However, BMI does not distinguish between muscle mass and fat. Athletic individuals who

may have heavy muscle mass could have a BMI

indicating that they are obese.

• BMI is also not adjusted across population groups.

Factors such as age and gender can make a big

difference.

• Nevertheless, keep in mind that BMI is normally

the calculation used around the world and in

Canada in relation to body weight comparisons.

The Effect of Exercise on Fat Lossand Muscle Gain


For most people, excess body weight impairs performance of physical activity.

• However, rapid and extreme weight loss can have

many detrimental consequences.

• Total energy intake combined with energy

expenditure are the most important things to

consider in adjusting one’s body weight.

• A gradual weight loss program ensures maximum

fat loss along with the preservation of lean muscle

tissue.

Should Being Underweight BeA Cause for Concern?

• The high value that North American society places

on thinness may explain why being “underweight”

(defined as a BMI of less than 18.5) is notgenerally seen as a health risk comparable to

being overweight or obese.

• Nevertheless,for some people,

being underweight

can definitely bea serious health

concern.

Chart Source: Canadian

Health Measures Survey,

2012-2013.


Is There An “Internal” Control Mechanism?


Set-point theory suggests that individuals who are dieting become more obsessed with food as their body tries to regain its “set-point.”Therefore, the theory maintains, dieting can be pointless and frustrating.

• Whether you support this theory or not, it actually

underlines the importance of a combinedapproach to altering body weight through limiting

caloric intake and increasing physical activity.

• Exercise, some experts believe, contributes to alower “set-point” level.

• Exercise also increases the amount of muscle

mass, which increases RMR.

The Vicious Cycle of Dieting


Energy Imbalances and Female Athletes


Failure to supply the body with enough overall calories for daily activities, especially if combined with exercise, creates a negative “energy drain.”

• Female athletes in particular need to pay specialattention to nutrition as well as overall energy

intake in their diets.

• For female athletes, energy imbalances can lead

to a number of serious health conditions.

• One of these conditions is known as the femaleathlete triad.

The Female Athlete Triad


The female athlete triad has three components:

• 1. low energy availability,

• 2. menstrual irregularities, and

• 3. low bone mass.

Athletes suffering from this triad mayexperience problems in any one of these three areas, but all are related to not taking in enough calories in their diets.

Female athletes who do not consume enough calories to match their activity levels invariably jeopardize both their performance and their health.

Nutrition Needs of Vegetarian Athletes


A well-balanced vegetarian diet can support an active lifestyle.

• Vegetarian diets tend to be high in carbohydrates

and low in fat, which naturally complementsthe dietary goals related to optimal sport

performance.

• However, like other athletes, vegetarian athletesneed to monitor their vitamin and mineral intake

and their energy needs.

Timing of Nutritional Intake for Athletes


The timing of nutritional intake is very important.

Pre-exercise nutrition.

• Ideally, this meal will be relatively high in complexcarbohydrates and low in both fat and fibre. The

portion should be small to moderate in size.

During-exercise nutrition.

• Maintenance of hydration is one of the main goalsof an athlete during competition and training.

Post-exercise nutrition.

• The nutrition goals of this period are to rehydrate,

refuel, and help promote adaptations.

Before, During, and After Exercise

Athletes and active individuals need to ensure balanced meals and snacks.


The Risks of Dehydration


Excessive fluid loss (dehydration) can lead to a number of dangerous conditions:

• Muscle cramps. The symptoms include painful

muscle twitches, followed by total muscle cramps.

• Heat exhaustion. Symptoms of this dangerous

condition include a high body temperature; pale, cool, and clammy skin; light-headedness; and

possibly loss of consciousness.

• Heat stroke. A life-threatening condition that

occurs when there is a complete failure of

the body’s heat-regulatory system. Symptoms

include a very high body temperature, headache,

confusion or behavioural change, and possibly a

loss of consciousness.

Lesson 14.4


SUMMARY

• Body Mass Index (BMI) is a measure widely used

to assess the extent to which individuals are

underweight or overweight.

• BMI is easy to measure and to compute, but its

main weakness is that it does not distinguish

between muscle mass and fat.

• For some people, being underweight can definitely

be a serious health concern.

• Female athletes in particular need to pay special

attention to nutrition as well as overall energy

intake in their diets.

• The timing of nutrient and fluid intake is also very

important for persons who are active.

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