Energy Balance, Wellness, and Human Nutrition

Energy Expenditure and Basal Metabolism

Total Daily Energy Expenditure (TDEE): The total amount of energy an individual uses in a day, composed of several distinct factors: - Basal Metabolism (BMR): Energy expended to maintain the body’s resting functions (e.g., breathing, circulation). This accounts for the largest portion of daily energy use. - BMR Rate for Women: $0.9\,kcal/kg$ per hour. - BMR Rate for Men: $1.0\,kcal/kg$ per hour. - BMR Contribution: Typically accounts for $50-70\%$ of TDEE. - Thermic Effect of Exercise (TEE): Energy spent during intentional and unintentional movement. It accounts for $-20-35\%$ of TDEE. - Physical Activity: Planned exercise sessions. - Adaptive Thermogenesis: Energy used by the body to adjust to environmental changes or physiological stress. - Nonexercise Activity Thermogenesis (NEAT): Energy used for activities other than sleeping, eating, or sports-like exercise (e.g., fidgeting, walking to class, standing). - Thermic Effect of Food (TEF): The energy required to digest, absorb, transport, store, and metabolize nutrients. It accounts for approximately $10\%$ of TDEE.

Regulation of Eating Behavior

Appetite vs. Hunger: While hunger is a physiological drive to eat, appetite is a psychological desire often triggered by sensory cues.
Brain Regulation Centers (Hypothalamus): - Hunger Center: Located in the Lateral hypothalamus. - Satiety Center: Located in the Ventromedial nucleus.
Specific Nuclei of the Hypothalamus: - Preoptic nucleus - Anterior hypothalamic area - Supra-optic nucleus - Paraventricular nucleus - Lateral hypothalamic area - Dorsal hypothalamic area - Posterior hypothalamic area - Dorsomedial nucleus - Ventromedial nucleus - Mammillary body
The Satiety Process: - Stomach Signals: Stretch-sensitive neurons detect mechanical expansion when the stomach is full. - Hormonal Messengers: CCK, Peptide YY (PYY), and Glucagon-like peptide-1 (GLP-1) signal fullness. - Leptin: A hormone produced by adipose tissue that provides long-term regulation of fat stores and suppresses appetite. - Cerebral Cortex Influence: Conscious thinking takes place here and can override physiological hunger or satiety signals (e.g., eating when full due to the flavor of food or knowing a meal was just eaten).

Satiety and Hunger Hormones

Leptin Functions: - Decreases glucose-stimulated insulin secretion. - Inhibits Neuropeptide Y (NPY). - Regulates appetite and helps control metabolism and energy homeostasis. - Contributes to high blood pressure and increased heart rate. - Regulates the synthesis of thyroid hormones and the menstrual cycle. - Activates immune cells and regulates bone mass.
Hunger Stimulants: - Ghrelin: Secreted from the stomach when empty to stimulate hunger. - Neuropeptide Y (NPY): Produced in the hypothalamus; powerful hunger stimulant. - Cortisol: Produced in the adrenal cortex; stimulates appetite.
Effect of Hormones and Neuropeptides on Appetite (Table 10.4): - Amylin (Pancreas): Inhibits. - Cholecystokinin (CCK) (GI Tract): Inhibits. - Glucagon (Pancreas): Inhibits. - Glucagon-like peptide 1 (GLP-1) (GI Tract): Inhibits. - Insulin (Pancreas): Inhibits. - Leptin (Adipose tissue): Inhibits. - Obestatin (GI Tract): Inhibits. - Oxyntomodulin (GI Tract): Inhibits. - Pancreatic Polypeptide (Pancreas): Inhibits. - Peptide YY (PYY) (GI Tract): Inhibits. - Proopiomelanocortin Derivatives (Pituitary): Inhibits. - Agouti Related Peptide (Brain): Stimulates. - Thyroxine (T4) / Triiodothyronine (T3) (Thyroid): Stimulates.

Body Weight and Composition Assessment

Body Mass Index (BMI): - Metric Formula: $BMI = \frac{\text{Weight (kg)}}{\text{Height}^2\, (m)}$ - Imperial Formula: $BMI = \frac{\text{Weight (lbs)}}{\text{Height}^2\, (in)} \times 703$
Methods for Measuring Body Fat Content: - Underwater Weighing (Hydrodensitometry): Based on Archimedes’ principle; calculates body density. SE: $-2-3\%$ . Cost: $\$40-60$ . - Air Displacement (BodPod): Measures air displacement. SE: $-2-3\%$ . Cost: $\$40-60$ . - DEXA (Dual Energy X-ray Absorptiometry): X-ray technique at two energy levels; images fat and bone mass. SE: $-1-2\%$ . Cost: $\$100-300$ . - Skinfold Thickness: Measures subcutaneous fat folds. SE: $-3-4\%$ . Cost: $\$10-20$ . - Bioelectrical Impedance Analysis (BIA): Measures resistance to electrical current. SE: $-3-4\%$ . Cost: $\$30-40$ . - Anthropometry: Measures body segment girths. - Computed Tomography (CT) and MRI: Scans for deep abdominal fat; accurate but expensive.

Body Fat Distribution and Adipose Physiology

Types of Fat: - Essential Fat: Necessary for health ( $3\%$ in men; $12\%$ in women). - Stored Fat: - Subcutaneous Fat: Fat stored directly under the skin. - Visceral Fat: Fat stored deep in the abdominal cavity around organs. High levels are linked to chronic disease.
Upper Body Obesity Definitions: Assessed by waist circumference. - Males: >40\,inches - Females: >35\,inches - Health Risks: Cardiovascular disease, Hypertension, Type 2 diabetes.
Adipose Tissue Types: - White Adipose Tissue (WAT): Single large lipid droplet (Triacylglycerol); stores energy. - Brown Adipose Tissue (BAT): Multiple small droplets; high mitochondria count; contains Uncoupling protein 1 (UCP 1) for thermogenesis (burning energy to create heat).
Energy Dynamics: - $1\,lb$ of body fat is approximately equal to $3500\,kcal$ . - Safe weight change: $2\,lbs$ per week (requires a deficit or surplus of $7000\,kcal$ per week or $1000\,kcal/day$ ).

Diet Philosophies and Content

Macronutrient Comparisons (Table 11.4): - Weight Watchers: 1,450 kcal; $56\%$ Carb / $24\%$ Fat / $20\%$ Protein. - Atkins: 1,520 kcal; $11\%$ Carb / $60\%$ Fat / $29\%$ Protein. - Zone: 1,660 kcal; $40\%$ Carb / $30\%$ Fat / $30\%$ Protein. - Ornish: 1,520 kcal; $77\%$ Carb / $6\%$ Fat / $17\%$ Protein.
Paleo: Philosophy of eating like Paleolithic humans. - Restrictions: Processed foods, dairy, grains, sugar, legumes, processed oils, salt, alcohol, coffee. - Cons: High saturated fat, low calcium/Vitamin D.
Keto: Focus on fat-burning through carbohydrate restriction. - Cons: Constipation, kidney stones, stunted growth in children.
Intermittent Fasting: No calories for $16\,hours/day$ to lower insulin levels and liberate fat stores.

Eating Disorders and Specific Conditions

Major Disorders: Anorexia nervosa, Bulimia nervosa, Binge-eating disorder.
Specialized Conditions: - Muscle Dysmorphia (Bigorexia): Obsession with muscle mass. - Orthorexia: Obsession with healthy eating. - Pregorexia: Disordered eating during pregnancy. - Prader-Willi Syndrome: Genetic disorder causing insatiable hunger. - Pica: Consumption of non-food items, including: - Geophagia (Soil/clay), Acuphagia (Sharp objects), Hematophagia (Blood), Trichophagia (Hair), Urophagia (Urine), Xylophagia (Wood), Dermatophagia (Skin), Hyalophagia (Glass), Coprophagia (Feces).

Wellness Pillars (The Big 6)

1. Sleep: Target $7-9\,hours$ ; wake/sleep at the same time ( $\pm 1\,hour$ ). Use sunlight in morning/afternoon and keep rooms dark/cool ( $65^{\circ}F$ ).
2. Light/Dark: Morning sunlight exposure for $10-20\,mins$ . Light inhibits melatonin; cortisol peaks in the morning during wakefulness. - Caffeine and Adenosine: Caffeine is structurally similar to adenosine (a sedative). It competes for adenosine receptors, preventing fatigue signals.
3. Movement: - Zone 2 Cardio: $180-220\,mins$ per week. - Resistance Training: $6-10\,sets$ per muscle group.
4. Nutrition: Focus on unprocessed/minimally processed foods.
5. Social Connection: Foster positive connections and limit energy-taxing interactions.
6. Stress Control: - Physiological Sigh: Mechanism to manage real-time stress ( $2\times$ inhale followed by a long exhale). - Stress Tolerance: Increased through meditation and cold exposure.