Study Guide: Energy Balance, Obesity, and Weight Management

What is meant by energy balance

Energy intake = energy output

energy intake:

• carbs

• protein

• fat

• alc

Energy output:

• basal metabolism

• thermic effect of food

• physical activity

What are the 3 main components of energy expenditure?

• basal metabolism

• thermic effect of food

• physical activity

Basal metabolism: meaning and % of energy expenditure

min amnt of cals used by body to stay alive: maintains body temp, blood, breath, etc

• 60-80%

Physical activity: % of energy expenditure

15-30%

thermic effect of food: meaning and % of energy expenditure

energy cost of digesting + absorbing food

• 8-15%

What factors impact a person’s BMR?

increasing BMR:

• lean body mass

• illness/injury

• excess thyroid hormones

• stress

Decreasing BMR:

• aging

• starvation/low-cal diets

What is BMI?

weight (kg)/height (m)2

measures amount of body fat depending on their height and weight

BMI: underweight, normal, overweight, obese + risks

Underweight: <18.5

• infertility

• high risk of heart disease/stroke

• decreased immune function

Normal: 18.5-24.9

Overweight: 35-29.9

• diabetes

• heart disease/stroke

• hypertension

Obses: 30+

What has been the trend in the prevalence of obesity in the U.S. in recent decades?

• 2014: 25% prevalence

  • midwest + south had highest prevalence

• Now: ¾ of U.S adults are overweight/obese, 1/3 U.S children are overweight/obese

What are some limitations of using BMI to assess health status

• doesn’t take muscle mass into account or location of body fat

• varies by age since muscle declines w age

• originally based on european white men

Alternative methods to BMI

• Percent body fat:

• men:

  • 18-24%: average

  • >25% unhealthy

• Women:

  • 25-31%: average

  • >32%: unhealthy

Visceral vs Subcutaneous fat

visceral: on the inside

subcutaneous: on the outside

What is the difference between central (android) obesity and gynoid obesity?

Central:

• stored around the abdomen and waist

• more common in men

• associated w type 2 diabetes, CVD, hypertension

Gynoid:

• stored around hips, thighs, and butt

• more common in women

• lower risk for chronic disease

What are some physiological (inside-the-body) theories about the cause of obesity

• genetics, epigenetics (environment and behavior) and obesity

• gut microbiome and dysbiosis

• white adiopose tissue: energy storage

• brown adipose tissue (BAT): energy storage and maintain body temp, helps keep people lean

What are some environmental (outside-the-body) theories about the cause of obesity?

• overeating

• food supply is unhealthy and adictive

• physical inactivity: screen time, sedentary jobs

• neighborhoods: rely more on cars than walking

What are the three lifestyle components of a successful weight management program?

• Diet

  • manage portion sizes

  • eat high fiber, lean protein

• Physical activity

  • no more than 2 lbs/week weight loss

• Behavior modification: tips to eat less

  • shop after eating, shop for healthy stuff

  • meal planning

  • reduce triggers

What is different about the new class of anti-obesity drugs (GLP1’s) as

compared to older weight loss drugs? In simple terms, how do these drugs work?

GLP1: semaglutide, tirzepatide

• glp1 and gIp receptor agonists; reduces appetite, increases fullness and satiety