Estimating Energy Expenditure and Activity Factors

Estimating Energy Expenditure

• Metabolic measuring systems detect changes in oxygen consumption, carbon dioxide production, or heat to estimate metabolism.
• Prediction equations using age, activity level, and weight, are simpler estimation methods.
• Over-the-counter devices often measure carbon dioxide production to estimate calorie burn.
• Complex research equipment, like whole-room calorimeters, detect gas exchange and heat changes.
• Prediction equations are a practical way to estimate calorie needs, though accuracy varies.
• The prediction equation can be used by males and females over the age of 19 by using values for age, physical activity factor, weight (in kilograms), and height (in meters).

Physical Activity Factors

• A physical activity factor is required if using the prediction equation; higher factors indicate higher activity levels.
• For example, an active male would use a factor of 1.25 in the equation.

Weight Management and Metabolic Health

• Health should be the primary focus of weight management, not unrealistic body ideals from the media.
• Obesity is a risk factor for chronic diseases; a range of healthy body weights exist.
• Metabolic health is characterized by normal blood pressure, glucose, and lipids, plus adequate physical activity.
• Important aspects of health include nutritious food and avoiding excess calories, especially from added sugars.
• Added sugars can promote inflammation and abnormal blood lipids, even without weight gain.
• Adequate micronutrient intake is vital, as many in the U.S. fall short, because micronutrients support metabolism.

Sustainable Weight Loss Tips

• Sustainable plans increase the likelihood of long-term weight management success.
• Avoid fad diets that require subscriptions, eliminate food groups, or focus on single foods.
• Adopt smaller portion sizes, consume more vegetables and dietary fiber, and consume lean protein sources.
• Sustainable weight loss requires time and patience; avoid making too many rapid changes at once.
• Making fewer changes at once leads to longer term success.
• Regular physical activity, including enjoyable activities like dancing and strength training, is key.

Dietary Habits and Long-Term Weight Loss

• Gradual weight loss indicates sustainable lifestyle changes.
• Eating breakfast, including lean protein and fiber, promotes fullness and kickstarts the metabolism.
• Only 5% of people in the U.S. meet dietary fiber recommendations.
• Increase fiber intake gradually to allow the gastrointestinal tract to adjust.
• Weekly weight tracking and stress control are habits promoting long-term weight loss.
• Apps and food diaries help track calorie and nutrient intake.

Metabolic Health vs. Weight

• Metabolic health should be seen as an overall indicator of health and not weight status.
• Metabolic health includes normal blood lipids, glucose, pressure, and waist circumference.
• About 25% of Americans with normal BMIs are metabolically unhealthy.
• Some individuals categorized as obese based on BMI are metabolically healthy.

Body Mass Index (BMI)

• BMI is a weight-to-height ratio, but it's not a direct indicator of body fat percentage.
• BMI is a useful tool to indicate potential health risks, when other measures are evaluated.
• BMI ranges: healthy (18.5-24.9), underweight (under 18.5), obese (30 or higher).
• BMI calculation using pounds and inches: weight (lbs) / [height (in)]2 x 703.
• Research shows higher mortality risks for BMIs below 18.5 and above 30.

Diagnosing Overweight and Obesity

• Diagnosis is done by using BMI alongside other measures of body fat distribution of body composition.
• Body fat distribution impacts health risk, with abdominal fat posing a higher risk.
• Carrying weight around the abdomen is a risk factor for cardiovascular disease and insulin resistance.
• Excess visceral fat, stored in the abdominal cavity around organs, increases inflammatory messengers.
• Increased inflammatory messengers are linked to type 2 diabetes and cardiovascular diseases.
• Fat stored below the abdomen carries less risk for insulin resistance and cardiovascular issues.

Hormonal Effects of Adipose Tissue

• Excess adipose tissue secretes hormones like estrogen, increasing breast cancer risk in postmenopausal women.
• Excess estrogen impacts fertility in childbearing years.
• Excess visceral fat in men decreases sperm production.
• Excess adipose tissue lowers fertility in women of childbearing age due to hormonal effects on menstrual cycles and ovulation.

Central Obesity and Waist Circumference

• Central obesity, or Android obesity, is more common in postmenopausal women due to hormonal changes.
• Men experience andropause, a gradual decline in testosterone, causing similar symptoms to menopause.
• Central obesity carries a higher risk for heart disease.
• BMI and waist circumference measurements can asses cardiovascular risk.
• Measure waist circumference above the pelvic bone (iliac crest).
• High-risk waist circumference: women > 35 inches, men > 40 inches.

Measuring Body Fat Percentage

• Skinfold calipers are a way to estimate body fat percentage by pinching skin and subcutaneous fat.
• Bioelectrical impedance (BIA) devices estimate body fat by sending electrical currents through the body.
• BIA devices measure resistance against the sent electrical current to estimate fat.
• More accurate BIA devices have contact points for bare feet and hands.
• BIA devices have a margin of error of 3-4%, which can be unacceptable for some.
• BIA devices can overestimate or underestimate body fat based on hydration levels; hydration status must be normal.
• Dual-energy X-ray absorptiometry (DEXA) scans, primarily used clinically for bone density, are the most accurate.

Health Risks of Body Fat

• Underweight leads to lowered immunity, trouble maintaining lean tissue, menstrual irregularities, infertility, osteoporosis, and higher mortality.
• Excess body fat increases inflammatory adipokine production, leading to inflammation and insulin resistance.
• Excess weight and high waist circumference raise the risk of hypertension, atherosclerosis, strokes, and heart attacks.
• Type 2 diabetes contributes to Alzheimer's, kidney disease/failure, amputations, and neurological/cognitive issues.

Comprehensive Health Risk Assessment

• Use individual risk factors in combination with BMI to determine at-risk patients.
• Individual risk factors include waist circumference, muscle mass vs. fat mass, blood pressure, blood glucose, and blood lipids.

Components of Energy Balance

• Energy balance is when calorie consumption equals calorie expenditure.
• Weight loss occurs when more calories are expended than consumed.
• One must consider whether an individual is getting adequate amounts of nutrients, and dietary fiber.
• Metabolism and energy expenditure are influenced by:
  • Basal metabolic rate (BMR): 50-66% of total energy expenditure.
  • Thermic effect of food: 10% of energy expenditure.
  • Physical activity: the most variable component.