Overview
This lecture covers fundamental nutrition concepts for exercise science, including nutrients, macronutrient guidelines, energy balance, body composition, and the professional scope of nutrition advice.
Scope of Practice for Fitness Professionals
- Fitness professionals cannot prescribe individualized meal plans; that's limited to registered dietitians.
- You can discuss general nutrition, macronutrients, and offer basic food suggestions based on public guidelines.
- Nutrition scope varies by state; know your legal limits.
Classes of Nutrients & Macronutrients
- Six classes of nutrients: carbohydrates, fats, proteins, water, vitamins, and minerals.
- Macronutrients: carbohydrates, fats, and proteins; provide energy and are required in large amounts.
- Carbohydrates: 4 kcal/gram; should make up 45-65% of diet; main energy source.
- Proteins: 4 kcal/gram; RDA is 0.8g/kg; important for muscle and cellular function.
- Fats: 9 kcal/gram; should be 20-35% of diet; include saturated, unsaturated, and trans fats.
Body Composition and Obesity
- Obesity: excessive fat, especially around the torso, increases risk for diseases like diabetes and cancer.
- BMI: only considers height and weight; BMI 25–29.9 = overweight, ≥30 = obese.
- BMI does not distinguish between fat and lean mass; less accurate for athletes.
- Android (apple) shape = higher risk; gynoid (pear) shape = lower risk.
Factors Affecting Nutrition & Obesity
- Socioeconomic status, education, culture, environment, and screen time impact dietary habits.
- Food deserts and limited access to healthy food contribute to obesity.
Dietary Guidelines & Label Reading
- Follow Dietary Guidelines for Americans: focus on variety, nutrient density, limit added sugars/fats.
- Food labels now show serving size, calories, macronutrients, added sugars, and key vitamins/minerals.
Special Considerations for Athletes
- Endurance athletes: 8–10g carbs/kg/day; strength athletes: 5–6g carbs/kg/day and 1.4–1.7g protein/kg/day.
- Try fueling strategies (e.g., gels) before events to avoid GI issues.
Water, Micronutrients & Supplements
- Water is essential for physiological processes; loss >2% body weight impairs performance.
- Recommended daily water: 2.7L (women), 3.7L (men), but needs vary.
- Micronutrients (vitamins/minerals) are vital for health; best obtained from food, not supplements.
- Supplements are not well-regulated.
Energy Balance & Weight Management
- Energy expenditure = resting metabolism + activity + thermic effect of food.
- Safe weight loss: 1–2 lbs/week (~3500–7000 kcal deficit/week).
- Resistance training increases resting metabolic rate.
- Adherence and feeling full are key factors in sustainable weight loss.
Body Composition Assessment
- Methods: skinfolds, BodPod, DEXA, underwater weighing.
- Fat mass vs. fat-free mass (lean mass: muscle, bone, water, organs).
Key Terms & Definitions
- Registered Dietitian — Licensed professional qualified to provide individualized nutrition advice.
- Macronutrients — Nutrients needed in large amounts: carbs, fats, proteins.
- BMI (Body Mass Index) — Weight (kg) / height (m²), used to classify overweight/obesity.
- Glycemic Index — A measure of how quickly a carbohydrate raises blood sugar.
- Nutrient Density — Amount of nutrients per calorie in food.
- Energy Density — Calories per unit weight of food.
- Basal/Resting Metabolic Rate (BMR/RMR) — Calories used at rest for basic body functions.
- Thermic Effect of Food — Energy used to digest and process food.
- Fat-free Mass — All body mass that is not fat (includes muscle, bone, organs).
- Android/Gynoid — Android: fat around abdomen; Gynoid: fat around hips/thighs.
Action Items / Next Steps
- Review myplate.gov and dietaryguidelines.gov for recommended macronutrient distributions.
- Practice calculating BMI and RMR using provided formulas.
- Read required textbook chapters on nutrition fundamentals and body composition.
- Prepare questions about scope of practice and nutrition calculations for next class.