Nutrition D.3 Flashcards
D.3.1 Define the term basal metabolic rate (BMR).
Minimum energy requirement for maintainance of biological activity in the body
D.3.2 State the components of daily energy expenditure.
- Thermic effect of feeding (TEF)
- Thermic effect of physical activity
- BMR (Basal metabolic rate)
D.3.3 Explain the relationship between energy expenditure and intake.
- Disturbing the energy balance between expenditure and intake causes either a net gain in body mass or a net loss in body mass
intake > expenditure = net gain in body mass (weight gain)
expenditure > intake = net loss in body mass (weight loss)
D.3.4. Discuss the association between body composition and athletic performance.
- Endurance athletes tends to be small and slender while strength and power athletes tend to be more muscular and have higher FM
- This suggests there is optimal body morphology for success in different types of effort
D.3.5. Discuss dietary practices employed by athletes to manipulate body composition
Body mass and body composition can be influenced, to some degree, by a combination of training and dietary behaviors:
- Gaining muscle mass (increasing FFM)
- Losing fat mass (decreasing FM)
- Dehydration
What is fat mass (FM)?
The mass of all lipids in the body which can be extracted
What is fat free mass (FFM)?
The mass of all remaining tissues and materials which do not include fat mass
What is thermic effect of food (TEF)?
Energy needed to process food – the energy needed to digest food and to absorb, transport and store the nutrients derived from it
What is thermic effect of physical activity?
Muscle-driven movement which increases energy expenditure
What is energy balance?
Energy intake and energy ependiture tend to be closely balanced in healthy adult humans, so this relationship is refered to as energy balance
How can FM and FFM be measured?
- Skinfold caliper measures
- Bioelectrical impedance
- Underwater weighing
- Dual x-ray absorptiometry (DEXA)
Healthy weight loss strategies for athletes
- 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 must meet energy costs of living, growth, sports activities (intake kcal > 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
Healthy weight gains strategies for athletes
- 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
Ways to gain muscle mass (FFM)
- 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
Ways to lose fat mass (FM)
- Lower energy intake
- Increase energy expenditure
For example: Increase physical activity, becoming more active
What is dehydration?
- In sports that require “weigh-ins” (boxing), some competitors will restrict food and fluid intake to achieve a body mass in order to compete in a weight class below their normal day-to-day body mass
- The aim is to attempt to gain a weight advantage over an opponent
- Tradeoff is dehydration and low energy stores
What are the typical levels of FM and FFM?
- 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
