Weight and energy balance

• obesity


  25 to 40 pounds more than healthy weight. Over 37percent of those Americans are obeseClassified as a disease by the A M A in 2013
• Risks of being overweight

  Hypertension and strokeHeart diseaseGallbladder diseaseType 2 diabetesOsteoarthritisSome cancersSleep apnea
• Risks of being overweight

  Hypertension and stroke

  Heart disease

  Gallbladder disease

  Type 2 diabetes

  Osteoarthritis

  Some cancers

  Sleep apnea
• BMI measurements for what is healthy and isn't

  B M I ≥ (greater than) 25 is overweight: modest increase in risk of dying from diseases

  ≥ 30 is obese: 50 to 100 percent higher risk of dying prematurely compared to healthy weight

  < (less) 18.5 is underweight; can also be unhealthy

  May not be accurate for everyone

  Does not directly measure % body fat
• Health benefits from losing 5 to 10 pounds

  Lower blood pressure, cholesterol, and glucose
• Healthy percentage of body fat for average adult male and female

  Average adult male between 20 and 49 years of age: 16% to 21% percent of weight is body fat

  Average healthy female: 22% to 26% percent body fat
• Central obesity (excess visceral fat) vs subcutaneous fat


  increases risk of heart disease, diabetes, hypertension

  Measure waist circumference
• basal metabaolic rate (B M R)


  minimum amount of energy you need to function

  Amount needed to meet basic physiological needs, keep you alive

  Makes up about 60 percent of total energy needs

  Many factors affect B M R, chiefly lean body mass
• The thermic effect of food

  affects your energy needs

  Amount of calories expended to digest, absorb, and process food (about 10 percent of calories in food eaten)
• Physical needs and energy needs

  Energy expended by sedentary people = less than half of B M R

  Very active athletes can expend twice B M R

  Exercise causes small increase in energy expenditure after activity has stopped.
• Energy Imbalances and Weight Loss:

  Reducing calories can lead to weight loss

  Stored glycogen and fat are used as fuel sources

  Amino acids from body protein breakdown can be used to make glucose

  Prolonged fast depletes all liver glycogen

  Ketone bodies generated from incomplete breakdown of fat

  Fat stores and about one-third of lean tissue mass depleted in about 60 days
• Physiological factors that lead to hunger

  Many hormones play a role:

  Ghrelin: produced in stomach when empty; increases hunger

  When fat stores increase, leptin in fat tissue signals brain to decrease hunger and food intake.

  Cholecystokinin: released when stomach is distended, increasing feelings of satiation, decreasing hunger

  Protein, fatty acids, and monosaccharides in small intestine stimulate feedback to brain to decrease hunger

  Insulin also causes brain to decrease hunger

  Many people override feedback mechanisms, resulting in energy imbalance
• Factors in weight management:

  what and how often you eat, physiology, genetics, environment

  Hunger and appetite affect what you eat

  Appetite is psychological desire for food

  Hunger is physiological need for food; subsides as feeling of satiation sets in
• Weight gain and energy (calorie) imbalance

  Excess calories (energy) can lead to weight gain

  Excess calories are stored as fat, regardless of source

  Limited capacity to store glucose as glycogen

  Can't store extra protein

  Unlimited capacity to store fat

  Body contains about 35 billion fat cells, which can expand
• Satiety


  Satiety determines length of time between eating episodes
• non-exercise-associated thermogenesis (N E A T):

  energy expenditure in nonexercise movements, such as fidgeting, standing, chewing gum
• What genetic differences in function of hormones that lead to obesity?

  high ghrelin or low leptin levels, increase obesity

  Many obese have adequate leptin, but brain has developed resistance to it
• Gene-environment interaction:


  increases risk of obesity in some people
• where do we get most of our calories from?

  32 percent of calories come from ready-to-eat foods prepared outside of home

  Frequent dining out associated with higher B M I
• National Institutes of Health - in losing weight healthily?

  overweight individuals should aim to lose about 10 percent of body weight over 6-month period

  Example: 180-pound person should lose 18 pounds/6 months = 3 pounds/month, ¾ pounds/week

  To lose 1 pound of body fat, need 3,500-calorie deficit

  For a weight loss of ½ to 1 pounds/week, need to decrease daily calories by 250 to 500 calories

  Fad diets promise dramatic results but may carry risks
• Environmental factors affecting body weight

  Environmental factors can increase appetite and decrease physical activity

  Environment of cheap and easily obtainable energy-dense foods stimulates appetite
• My Plate as Weight Loss Guide:

  High volume of fruits, vegetables, whole grains, some lean protein, modest amounts of fat

  Diet should contain variety of foods from all food groups

  Replace higher-calorie foods with lower-calorie options from each food group.

  Example: replace full-fat dairy with nonfat products

  Replace sodas with water
• Behavior modification


  change behaviors that contribute to weight gain or impede weight loss

  Techniques include keeping food log, controlling environmental cues that trigger eating, managing stress
• Reduction of ..., not .... of diet, is key to weight loss


  Reduction of calories, not composition of diet, is key to weight loss
• High dropout rates for which extreme diets?

  Atkins and Ornish diets
• Beware of fad diet claims and hype:

  "It's carbs, not calories, that make you fat!"

  "Lose seven pounds in one week!"

  Celebrity-endorsed miracle weight-loss products

  "Natural" substances help lose weight without risk
• Extreme obesity BMI and risks


  B M I > (greater) 40 = extreme obesity

  High risk of heart disease, stroke, dying

  Requires aggressive weight-loss treatment, including very-low-calorie diets, medications, and/or surgery
• Very-low-calorie diets


  < (less than) 800 calories are short-term and must be medically supervised
• What medications cannot replace low cal diet?

  Orlistat, Belviq, and Qsymia can't replace a lower-calorie diet, physical activity, and behavior modification

  However, they impact appetite and help individuals lose from 3-9 % of their body weight when combined with diet and exercise
• Gastric bypass and gastric banding in levels of hunger


  result in higher levels of satiety and lower levels of hunger

  Results in dramatic weight loss and reduction of hypertension, diabetes, high blood cholesterol, and sleep apnea

  Small risk of gallstones, death from surgery
• Liposuction


  performed for cosmetic reasons

  Fat may reappear; results are not permanent

  Complications such as infections, scars, swelling
• weight cycling


  (repeated gain and loss of body weight) is common result of fad diets
• energy gap


  Physical activity can close the "energy gap," which is easier than further reducing caloric intake

  estimated that the energy gap is about 8 calories per pound of lost weight
• Gaining weight healthily


  Need to add at least 500 calories to daily energy intake for gain of 1 pound/week

  Choose more energy-dense but nutritious foods from each food group

  Examples: waffle instead of toast, coleslaw instead of cabbage

  Eat more snacks during day to add more calories
• disordered eating


  abnormal and potentially harmful eating behaviors that do not meet specific criteria for eating disorders
• eating disorders


  psychological illnesses that involve specific abnormal eating behaviors and other factors

  In United States, about 20 million women and 10 million men struggle with eating disorders at some point in life

  Most are adolescent or young adult white, middle- or upper-middle-class females, but increasing among males, minorities, other age-groups
• Sociocultural factors for disordered eating:

  Desire/social pressure to be thin or "cut"
• Genetic factors for disordered eating


  Eating disorders "run in families"
• Psychological factors for disordered eating

  Depression, anxiety, perfectionism, sense of control contribute
• anorexia nervosa


  results from severe calorie restriction

  Self-starvation and excessive weight loss

  Intense fear of being "fat"