Energy Balance, Body Composition, and Activity

Energy Balance, Body Composition and Physical Activity

• Energy Balance means that a person's weight remains stable over time.
• A healthy body weight is age, sex, and height appropriate, maintained without constant dieting, acceptable to the individual, and promotes good eating habits and allows regular physical activity.
• Energy intake equals energy expenditure in energy balance.
• Energy intake is the energy (kcal) from foods and beverages.
• Energy expenditure is the energy (kcal) used at rest and during activity.

Energy Intake Requirements

• Total Energy Expenditure is the Estimated Energy Requirement (kcal/day).
• Men's EER = 662 - (9.53 × age [y]) + PA × {(15.91 × weight [kg]) + (539.6 × height [m])}.
• Women's EER = 354 - (6.91 × age [y]) + PA × {(9.36 × weight [kg]) + (726 × height [m])}.

Energy Output

• Energy Output depends on basal metabolism, physical activities, and the thermic effect of food.
• Basal metabolism maintains life when a person is at complete digestive, physical, and emotional rest.
• Resting functions of the body, such as respiration and circulation, are fueled by basal metabolism.
• Basal metabolism supports the body's constant work, accounting for 50-65% of daily energy expenditure.
• Basal metabolic rate (BMR) indicates the rate at which a person expends energy.
• BMR varies from person to person and it is slowest when asleep.
• BMR is measured when awake but still, in comfortable temperature after rest and a 12-14 hour fast.
• BMR is impacted by age, height, growth, body composition, fever, stresses, temperature, fasting/starvation, malnutrition, hormones, smoking, caffeine, and sleep.
• Being a main contributor to BMR, the more lean tissue, the higher the BMR, which is why males usually have a higher BMR than females. The more fat tissue, the lower the BMR.
• Physical activity refers to voluntary movement of skeletal muscles, supporting systems above basal metabolism.
• Physical activity accounts for 30-50% of daily energy expenditure
• It is the most variable part of energy output
• Physical activity depends on duration, frequency, and intensity, and when you are active, the more frequent and more intense the activity, the more kcalories expended.
• Thermic effect of food estimates the energy required to process food, such as digestion, absorption, transport, metabolizing, and storage of nutrients.
• Cells become active when food is ingested, which require cellular activity which produces heat
• The thermic effect of food is proportional to the energy content of mixed meal (~10%). For example, if someone eats a 850 kcal dinner, about 85 kcal are spent for digestion, absorption and metabolism of the dinner.

Measuring Basal Metabolic Rate

• Direct calorimetry measure the amount of heat the body releases. 1 kcal = amount of energy (heat) required to raise 1 kg (1 L) of water by 1°C at sea level.
• Indirect Calorimetry estimates energy expenditure based on O₂ consumption and CO₂ release. It is less expensive and more accessible.
• Basal Metabolic Rate can be measured indirectly by measuring oxygen and carbon dioxide levels.
• BMR can also be measured using blood work to measure thyroid function tests (the thyroid regulates basal metabolic rate)
• The Harris-Benedict Equation enables mathematical estimation of formulas,

Estimating Energy Expenditure

• Energy Expenditure can depend on sex, growth, age, physical activity and body composition and body size. It also varies between individuals.

Energy Imbalance

• In Energy Imbalance, Weight Gain = Calories that are consumed exceed those that are expendatured
• In Energy Imbalance, Weight Loss = Calories that are expended exceed those that are consumed
• Underweight is having too little body fat to maintain health.
• Overweight is having a moderate amount of excess body fat.
• Obesity is having an excess of body fat that adversely affects health.

Evaluating Body Weight

• Person's actual weight is not the only factor to consider
• Determining if a person's body weight is healthy should include the Body Mass Index (BMI), body composition, and pattern of fat distribution of it.
• Body Mass Index (BMI) expresses the ratio of a person's weight to the square of their height.
• BMI = weight (kg) / height (m)²
• BMI helps define Underweight, overweight, and obese
• A healthy weight falls between BMI of 18.5-24.9
• Health risks increase as BMI falls below 18.5 & over 24.9
• BMI does not identify which weight is fat and how it is located
• Overweight has a BMI between 25 and 29.9
• Obesity occurs when a BMI greater than 30 and includes clinically obese people
• Underweight occurs when a BMI is below 18.5
• Certain limitations exists with BMI, including those under the age of 18 years, those are pregnant or nursing, over age 65 years, certain ethnic and racial groups and those high in muscle mass
• Fat/Body composition provides an assessment of lean body mass and percent body fat (different methods to access it)

Methods of Measuring Body Fat

• Dual energy X-ray absorptiometry (DEXA) estimates lean tissue, bone, mineral, and fat mass
• Hydrostatic (underwater) weighing can also be used for determination of body density
• Determination of body density
• Measurement of body density
• Bod Pod system measures body fat
• Estimate body density based on subcutaneous fat
• Bioelectrical impedance analysis (BIA) can also be used to measure total body water and fatness.

Ideals regarding Body Fat

• Enough to meet basic needs. This depends on the individual.
• 13 to 21 percent for men
• 23 to 31 percent for women

Evaluating Body Weight

• Fat distribution pattern is another factor to note
• Pear-shaped bodies are a lower body with fat accumulation in subcutaneous layer
• Apple-shaped bodies are an upper body with fat accumulation in the visceral laye
• The recommended waist-to-hip ratio is >0.9 for males and >0.8 for females

Gaining or Losing Weight

• Whether a person gains or loses weight depends on: Energy balance, genetic factors and physiological factors. Energy balance depends on energy intake vs. energy expenditure.
• Genetic factors (25%), non-genetic factors (75%).
• Different ideas explain the impact of genetics on body fat, which is called Thrifty Gene Theory and Set-point Theory.
• Set-point theory proposes body weight that is physiologically regulated.
• Physiological Factors are impact weight and can be Hunger and satiety, and Proteins Hormones such as leptin and ghrelin.
• Hormone leptin is produced predominantly by fat cells in proportion to stored fat, and gain in body fat stimulates production of leptin. Fat loss decreases leptin production and decreases energy expenditure.
• Ghrelin is a Protein/hormone that is synthesized and secreted primarily by stomach cells that can promote positive energy balance by stimulating desire to eat. Blood levels of ghrelin typically rise before and fall after a meal.
• Behavioural Factors can impact weight including appetite, which is when appetite can be defined as a psychological desire to eat
• Social Factors include family or cultural traditions, holidays and celebrations, easy access to high-fat foods.
• If you need to change/meet appropriate body weights then strategize around two goals: 1. change body weight by 5-10% over 6 month period and . maintain changed body weight over a period of years.

Diet for Healthy Body Weight

• Effective weight loss includes following recommended servings and portion sizes and eating smaller, more frequent meals.
• Diet for weight loss should include eat before you become extremely hungry
• Diet for weight loss should include eat more fresh and less processed foods and drink adequate water

Effective weight loss

• Foods with a low energy density and a high nutrient density (e.g. fruits and vegetables) is an important aspect of an effective diet. It's important to choose whole grains and fiber-rich vegetables when dieting as well as choose fats sensibly and including enough unsaturated oils
• Limit intake of added sugars and alcohol and drink adequate water. Replacing energy-dense beverages with water could save a person up to 15 pounds a year. Fad Diets should also be considered.
• Unlike FAD diets many do offer safe and effective plan for weight loss with legitimate research
• Nutrients are key for short term weight loss such as in a success diet plan

Diets for Weight Gain

• Effective weight gain should include for example: eating 500 to 1,000 extra kcal/day and maintaining a balanced diet. eat frequently throughout the day (at least 3 meals a day and snacks in between)
• Healthy people should choose energy-dense foods most often
• Drink calorific drinkse. avoiding tobacco products which depress appetite and increase BMR

Health Behaviour

• -application of behavioral modification techniques for those who are becoming aware of eating/lifestyle behaviours. This involves, making small changes and Adopting new ways of thinking

Physical Activity

• Physical activity, exercise, & physical fitness can be combined such as in leisurely physical activity.
• Exercise would be described as purposeful, planned physical activity
• Physical fitness depends on physical activity, or exercise

Benefits of Regular Physical Activity

• Improves body composition , bone density, and immune system and reduces the risk of chronic disease

Physical Fitness Program

• The ability to meet routine physical demands and the characteristics that enable the body to perform physical activity
• Physical Fitness should have a diet designed with nutrition and physical activity
• Physical fitness includes cardiorespiratory fitness, musculoskeletal fitness, flexibility and body composition and can build endurance, flexibility and Strength
• A sound physical fitness program should meet personal goals and be fun.
• It should also warm up and cool down and includes variety and variety- includes variety and consistency- includes variety and consistency

Overload Principle

• A sound physical fitness program should appropriately overloads the body which is determined by a FIT principle and includes Frequency the intensity of maximal heart rate
• Time (duration) of activity should accumulate all at once

Fuel for Physical Activity

• Adenosine triphosphate (ATP), the energy carrying molecule in the body
• First muscles only store enough ATP for 1 - 3 seconds of activity. The more creatine phosphate is released, the more energy is stored between seconds of maximal physical effort
• Therefore after creatine phosphate, carbohydrates and lipids are the next source of energy for the production of ATP. Therefore, proteins are not used extensively as fuel source for physical activity
• While performing the activity, messenger molecules (the hormone epinephrine) flow into the bloodstream to signal the liver and fat cells to release their stored nutrients, primarily glucose and fatty acids

Dietary Intake for Optimal Physical Performance

• High-carbohydrate diet • About 8 grams carbohydrate per kilogram of body weight
• Athletes perform at a greater capacity when dietary intake contains 20-35% of protein and fat.
• A proper diet requires both iron, calcium, zinc, and adequate fluid intake to support body demands through the physical activity level