Lesson 14.1 THE BASICS OF SPORT NUTRITION ~ ~ ~ TOPICS COVERED IN THIS LESSON (a) Macronutrients and Micronutrients (b) Dietary Fats: The Good and the Bad 2015 Thompson Educational Publishing, Inc. 1
Nutrients The foods we eat are made up of different components that we call nutrients. These nutrients are 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 for physical exercise. Micronutrients are found in small amounts in food. They include vitamins and minerals, which help in energy transfer and tissue synthesis. 2015 Thompson Educational Publishing, Inc. 2
Carbohydrates, Proteins, and Fats Macronutrients are the human body s direct sources of energy: carbohydrates, proteins, and fats. Macronutrients supply us with the energy we need for daily life and for physical exercise. Carbohydrates 4 Calories per gram (kilocalories) Protein 4 Calories per gram (kilocalories) Fat 9 Calories per gram (kilocalories) 2015 Thompson Educational Publishing, Inc. 3
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. 2015 Thompson Educational Publishing, Inc. 4
Classifying Carbohydrates ( Carbs ) Carbohydrates are divided into two main types: 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 contain many of the vitamins, minerals, proteins, and fibre that our bodies need. 2015 Thompson Educational Publishing, Inc. 5
The Glycemic Index The blood sugar (or blood glucose) level refers to the concentration of glucose (sugar) present in the blood. The body tightly regulates blood glucose 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. 2015 Thompson Educational Publishing, Inc. 6
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, and vegetables, are considerably better for us. 2015 Thompson Educational Publishing, Inc. 7
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). 2015 Thompson Educational Publishing, Inc. 8
Amino Acids Proteins are species-specific and organ-specific (i.e., within a single organism, muscle proteins differ 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 the foods we eat these are essential amino acids. Our bodies can produce the other 11 amino acids these are non-essential amino acids. 2015 Thompson Educational Publishing, Inc. 10
Daily Protein Requirements Daily protein requirements differ from individual to individual, depending on the energy demands placed on each person s body. 2015 Thompson Educational Publishing, Inc. 10
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 polyunsaturated fats (the so-called good fats), and Saturated Fats: Saturated and trans fats (the bad fats). 2015 Thompson Educational Publishing, Inc. 11
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 also makes 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. 2015 Thompson Educational Publishing, Inc. 12
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. 2015 Thompson Educational Publishing, Inc. 13
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). 2015 Thompson Educational Publishing, Inc. 14
Promoting Canadians Nutritional Health The federal department responsible for helping Canadians maintain and improve their health is Health Canada. Canada s first food guide, the Official Food Rules, was introduced 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. 2015 Thompson Educational Publishing, Inc. 15
Canada s Food Guide The food intake pattern recommended in the most recent Canada s Food Guide is based on current nutritional science. 2015 Thompson Educational Publishing, Inc. 20
Preventing Nutrient Deficiencies Since 1938, Health Canada has provided recommendations 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. 2015 Thompson Educational Publishing, Inc. 17
Be Wary of Nutrient Content Claims Manufacturers are permitted to use nutrient content claims, such as those below, to attract attention 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 energy is contained in the food item. 2015 Thompson Educational Publishing, Inc. 18
Nutrition Facts Tables on Food Products A Nutrition Facts table appears in a standard format on food product labels. The Nutrition Facts table is intended to present nutritional information in basically the same format 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. 2015 Thompson Educational Publishing, Inc. 19
A Nutrition Facts Table s Standard Format 2015 Thompson Educational Publishing, Inc. 20
The Portion (Serving) Size of a Food Item 2015 Thompson Educational Publishing, Inc. 21
Total Calories and 13 Core Nutrients 2015 Thompson Educational Publishing, Inc. 22
The Actual Amounts of Nutrients 2015 Thompson Educational Publishing, Inc. 23
What Exactly is % Daily Value? The % Daily Value column of the Nutrition Facts table is based on the recommended intakes for each 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. 2015 Thompson Educational Publishing, Inc. 24
% Daily Value on a Sample Product Label 2015 Thompson Educational Publishing, Inc. 25
Serving Size Matters When reading labels, be especially vigilant when it comes to 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 the serving size is, so that you can better understand the nutritional information on the label. 2015 Thompson Educational Publishing, Inc. 30
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. 2015 Thompson Educational Publishing, Inc. 27
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. 2015 Thompson Educational Publishing, Inc. 28
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. 2015 Thompson Educational Publishing, Inc. 29
The Energy Equation 2015 Thompson Educational Publishing, Inc. 30
What is a Food Calorie? A calorie is the amount of energy needed to raise 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. 2015 Thompson Educational Publishing, Inc. 31
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 2015 Thompson Educational Publishing, Inc. 32
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 to our specific activity level; and The energy needed to digest, absorb, transport, and store the food we ingest. 2015 Thompson Educational Publishing, Inc. 40
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. 2015 Thompson Educational Publishing, Inc. 34
Sustaining Bodily Functions The energy that needs to be consumed in order to sustain essential bodily functions is known as 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. 2015 Thompson Educational Publishing, Inc. 35
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. 2015 Thompson Educational Publishing, Inc. 36
The Harris-Benedict Equation The Harris-Benedict equation, dating back to 1918, is still widely used to arrive at a reasonably accurate estimate of RMR. The formula varies slightly for males and females: Males RMR = 66.5 + (5 x H) + (12.7 x W) - (6.8 x A) Females RMR = 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. 2015 Thompson Educational Publishing, Inc. 37
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 by 24.2; adult females can multiply their weight in kilograms by 22.0. This RMR figure can then be multiplied by an activity factor to estimate your daily caloric need requirements. For example: 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. 2015 Thompson Educational Publishing, Inc. 38
Health Canada s Daily Recommended Calorie Intake at Varying Activity Levels 2015 Thompson Educational Publishing, Inc. 39
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 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 (DCN) is the amount of calories we 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. 2015 Thompson Educational Publishing, Inc. 40
Body Mass Index (BMI) BMI is widely used to assess the extent to which individuals are underweight or overweight. 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 are considered obese. Individuals with a BMI of 18.5 or lower are considered to be underweight. 2015 Thompson Educational Publishing, Inc. 41
What s Flawed About the BMI Index? BMI is used worldwide to estimate body weight and to make comparisons across population groups. 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. 2015 Thompson Educational Publishing, Inc. 42
The Effect of Exercise on Fat Loss and 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. 2015 Thompson Educational Publishing, Inc. 43
Should Being Underweight Be A 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 not generally seen as a health risk comparable to being overweight or obese. Nevertheless, for some people, being underweight can definitely be a serious health concern. Chart Source: Canadian Health Measures Survey, 2012-2013. 2015 Thompson Educational Publishing, Inc. 44
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 combined approach to altering body weight through limiting caloric intake and increasing physical activity. Exercise, some experts believe, contributes to a lower set-point level. Exercise also increases the amount of muscle mass, which increases RMR. 2015 Thompson Educational Publishing, Inc. 45
The Vicious Cycle of Dieting 2015 Thompson Educational Publishing, Inc. 46
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 special attention 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 female athlete triad. 2015 Thompson Educational Publishing, Inc. 47
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 may experience 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. 2015 Thompson Educational Publishing, Inc. 48
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 complements the dietary goals related to optimal sport performance. However, like other athletes, vegetarian athletes need to monitor their vitamin and mineral intake and their energy needs. 2015 Thompson Educational Publishing, Inc. 49
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 complex carbohydrates 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 goals of an athlete during competition and training. Post-exercise nutrition. The nutrition goals of this period are to rehydrate, refuel, and help promote adaptations. 2015 Thompson Educational Publishing, Inc. 60
Before, During, and After Exercise Athletes and active individuals need to ensure balanced meals and snacks. 2015 Thompson Educational Publishing, Inc. 51
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. 2015 Thompson Educational Publishing, Inc. 52
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. 2015 Thompson Educational Publishing, Inc. 53