Nutrition, Energy Intake, and Body Composition Analysis

Comprehensive practice flashcards covering glycemic index, carbohydrates, fats, body composition measurement techniques, dietary reference values, BMR, and BMI.

What is the Glycemic Index (GI), and how are foods ranked on its scale?

The Glycemic Index describes how quickly a food containing carbohydrates increases blood glucose after eating. Foods are ranked on a scale from $0$ to $100$, with glucose having a score of $100$.

How do high GI foods affect the body, and why are foods like grapes, rice cakes, and jelly beans useful post-exercise?

High GI foods are broken down quickly in the body and cause a rapid rise in blood glucose. Grapes, rice cakes, and jelly beans are useful for optimal recovery because they stimulate insulin release and replenish muscle glycogen stores.

What are the characteristics and physiological benefits of low GI foods?

Low GI foods are broken down more slowly, causing a gradual increase in blood glucose. They help control appetite by keeping you full for longer, promote better glucose control, and maintain a more stable energy level.

Into what components are fats broken down when digested, and what sources provide them?

When digested and absorbed, fats break down into glycerol and fatty acids. Fats are obtained from animal and vegetable sources, and all dietary fats are a mixture of fatty acids.

What are examples of foods rich in saturated, monounsaturated, and polyunsaturated fatty acids?

Saturated: butter, fatty meat, chocolate, coconut oil, full-fat dairy products. Monounsaturated: olive oil, cashews, avocado, peanut oil, peanut butter. Polyunsaturated: salmon (only fish), nuts, rapeseed oil, vegetable oil.

Why might athletes cut back on fat intake during training and competition?

Cutting back on fat intake allows athletes to consume greater proportions of energy from carbohydrates, which maintains glycogen stores to support training and competition.

How much energy is provided per gram of fat?

Fat provides $9\text{ kcal}$ or $37\text{ kJ}$ per gram, making it more than twice as energy-dense as other macronutrients.

What are the primary functions of fats in the human body?

Fats provide a concentrated source of energy (forming the largest potential energy store), protect and cushion vital organs, provide structural material for cells, act as an insulator to maintain body temperature, provide vitamins A, D, E, and K, and add flavor and texture to food.

How are trans fatty acids produced, where are they found, and what health issue are they thought to cause?

Trans fatty acids are produced by the hydrogenation of vegetable oils (turning liquid into solid). They are found in hardened vegetable oils, most margarines, commercial baked foods, and most fried foods. An excess in the diet is thought to raise cholesterol.

What is the Recommended Daily Intake (RDI) of fat for males, females, and athletes?

Fat intake should represent $30\text{--}35\%$ of total calorie intake ($70\text{ g}$ per day for females, $90\text{ g}$ per day for males, with $6\text{--}10\%$ from saturated fats). Athletes in regular intense activity may reduce fat intake to $25\text{--}30\%$ of total energy.

What is the definition of a macronutrient?

A macronutrient is a nutrient required by your body in daily amounts that are greater than a few grams.

How much energy is provided by $1\text{ g}$ of carbohydrate?

$1\text{ g}$ of carbohydrate provides approximately $4\text{ kcal}$ or $17\text{ kJ}$ of energy.

What are simple carbohydrates, and when is the best time to digest them?

Simple carbohydrates consist of 1 or 2 sugar molecules that are digested and absorbed quickly (e.g., fruits, milk/dairy, sweets), causing a rapid increase in blood sugar and insulin. The best time to digest them is pre-event, during an event, or after an event.

What are complex carbohydrates, what are their components, and when is the best time to consume them?

Complex carbohydrates consist of long, linked chains of sugar molecules broken down slowly (e.g., oats, beans, vegetables, whole grains). They include starch (primary energy storage in plants), glycogen (stored in human muscles and liver), and dietary fibers like cellulose. The best time to digest them is pre-event, specifically hours before.

What is the Recommended Daily Allowance (RDA) of carbohydrates for the general population versus a marathon runner?

Around $50\%\text{--}60\%$ of total energy intake should be carbohydrates for the general population, whereas a marathon runner might need $65\%\text{--}70\%$.

What body composition test is illustrated in this diagram?

Bioelectrical Impedance Analysis (BIA), which estimates body composition by sending a safe, weak electrical current through the body.

What method of body composition measurement is shown in this picture, and how does body fat affect the measurement?

Hydrodensitometry. It works because body fat floats in water; an obese individual will measure a lower body density because high body fat floats, while an underweight individual will have a higher body density because less body fat floats.

What are the positives and negatives of using Bioelectrical Impedance Analysis (BIA)?

Positives: cheap, very quick, non-invasive, easy to administer. Negatives: not always accurate, and subjects must be fully hydrated when tested.

What tool is shown in this image, and how is it used in body composition testing?

Callipers. They are used in skinfold analysis to measure the thickness of fat at specific sites on your body.

What are Estimated Average Requirements (EAR) and Reference Nutrient Intakes (RNI)?

EAR is an estimate of average energy or nutrient requirements needed by a group ($50\%$ require less, $50\%$ require more). RNI is the amount of a nutrient that is enough to ensure the needs of nearly all ($97.5\%$) of a group are met.

What are Lower Reference Nutrient Intake (LRNI) and Safe Intake?

LRNI is the amount of a nutrient that meets the standards for only $2.5\%$ of people in a group who have low requirements. Safe Intake is used when there is insufficient evidence to set an EAR, RNI, or LRNI, representing an amount judged enough for almost everyone but below levels causing undesirable effects.

What is Basal Metabolic Rate (BMR), and what is the formula to calculate it for males?

BMR is the minimum number of calories needed everyday if stayed at rest. For males: $\text{BMR} = 66.5 + (13.75 \times \text{weight in kg}) + (5 \times \text{height in cm}) - (6.76 \times \text{age in years})$.

What is the formula to calculate Basal Metabolic Rate (BMR) for females?

For females: $\text{BMR} = 655.1 + (9.56 \times \text{weight in kg}) + (1.85 \times \text{height in cm}) - (4.68 \times \text{age in years})$.

How is Body Mass Index (BMI) calculated, and what are its standard weight classifications?

Calculated as $\text{BMI} = \frac{\text{weight (kg)}}{\text{height}^2 (\text{m}^2)}$. Classifications: Less than $18.50$ = Underweight, $18.50\text{--}24.99$ = Healthy weight, $25.00\text{--}29.99$ = Overweight, $30$ or more = Obese.

What are the potential limitations of using Body Mass Index (BMI)?

BMI is solely based on a person's height and weight, so it does not account for muscle mass, bone density, overall body composition, or racial and sex differences between individuals.