Nutrition D.3: Energy Balance and Body Composition

Question 1

D.3.1. Define the term basal metabolic rate (BMR).

Answer 1

Minimum energy requirement for maintainance of biological activity in the body

Question 2

D.3.2. State the components of daily energy expenditure.

Answer 2

1. Thermic effect of feeding (TEF)
2. Thermic effect of physical activity
3. BMR (Basal metabolic rate)

Question 3

D.3.3 Explain the relationship between energy expenditure and intake.

Answer 3

An imbalance between intake and expenditure leads to weight gain or loss.

• intake > expenditure = net gain in body mass (weight gain)
• expenditure > intake = net loss in body mass (weight loss)

Question 4

D.3.4. Discuss the association between body composition and athletic performance.

Answer 4

• Endurance athletes are small and lean
• Strength athletes are more muscular with higher fat mass.
• This suggests there is optimal body morphology for success in different types of effort

Question 5

D.3.5. Discuss dietary practices employed by athletes to manipulate body composition

Answer 5

1. Gaining muscle mass (increasing FFM)
2. Losing fat mass (decreasing FM)
3. Dehydration

Question 6

What is fat mass (FM)?

Answer 6

The mass of all lipids in the body which can be extracted

Question 7

What is fat free mass (FFM)?

Answer 7

The mass of all remaining tissues and materials which do not include fat mass

Question 8

What is thermic effect of food (TEF)?

Answer 8

Energy needed to process food – the energy needed to digest food and to absorb, transport and store the nutrients derived from it

Question 9

What is thermic effect of physical activity?

Answer 9

Muscle-driven movement which increases energy expenditure

Question 10

What is energy balance?

Answer 10

Energy balance is the relationship between energy intake and energy expenditure, usually stable in healthy adults.

Question 11

How can FM and FFM be measured? (important !!)

Answer 11

1. Skinfold caliper measures
2. Bioelectrical impedance
3. Underwater weighing
4. Dual x-ray absorptiometry (DEXA)

Question 12

Healthy weight loss strategies for athletes (important !!)

Answer 12

• Gradual weight loss - no more than 1 lb/week, 2 lb/week in mature athlete
• Weight loss is losing excess body fat, not muscle mass
• Calorie intake > BMR
• Maintain euhydration
• Preferable to lose weight in off-season
• Diet is well balanced and consists:
• Carbs: 6 - 10g/kg
• Protein: 0.85 - 1.7g/kg
• Fat: 1g/kg

Question 13

Healthy weight gains strategies for athletes (important !!)

Answer 13

• Gradual weight gain
• Weight gain as muscle mass:
• Boys = 0.5 - 1.0 lb / week
• Girls = 0.25 - 0.75 lb / week
• If maintaining body weight and eating recommended daily amount of protein:
• Eat 300 - 500 kcal above BMR
• Consume 1.5 - 1.8g protein/kg
• Strength train
• Get adequate sleep

Question 14

Ways to gain muscle mass (FFM)

Answer 14

• Strength training programs can cause muscle hypertrophy
• Athlete must train correctly, but also be in a positive balance = calorie surplus, including and adequate protein intake
• This may increase muscle strength but tradeoff is an increase in body mass

Question 15

Ways to lose fat mass (FM)

Answer 15

• Lower energy intake
• Increase energy expenditure

For example: Increase physical activity, becoming more active

Question 16

What is dehydration?

Answer 16

• In sports that require “weigh-ins” (boxing), athletes may limit food and fluids to qualify for a lower weight class.
• Aim is to attempt to gain a weight advantage over an opponent
• Tradeoff is dehydration and low energy stores

Question 17

What are the typical levels of FM and FFM? (important !!)

Answer 17

• Typical levels vary with gender, age, genetics, diet and level of physical activity
• Women tend to have higher FM than men
• If FM is either too low (<5% for men, <12% for women), or too high then health is threatened