Energy Balance and Weight Control

Energy Balance Overview

• 65-68% of all Americans are considered overweight

• 37-40% of all Americans are considered obese

• Gaining 10 pounds or 2 inches in the waist is signal for diet evaluation

• Proteins, carbohydrates, fats (consumption of energy yielding compounds) versus basal metabolism, thermic effect of food, physical activity, non-exercise activity thermogenesis (burning calories)
  

• Pay attention not to scales but to energy balance (energy input and output)

  • Positive balance – storage of excess energy (in the form of glycogen and fat)
    

  • Negative balance – energy deficit

Questions: What is the definition of overweight? What is the definition of obese?

Energy Intake

• Energy needs (kcals) are met by food intake

• Remember the 60-30-10 rule!
  

• Appropriate amount and type of food should be consumed to match energy needs

• Food supply versus consuming in America – average adult 10-12 pounds heavier then 10 yrs ago

• Bomb calorimeter is used to determine amount of energy in foods

• One kcal is the amount of energy required to increase the temperature of 1 kg of water one degree Celsius

• Remember kcals for carbohydrates, proteins, fats, and alcohol

• Fats 9 kcal/g but most fat consumed goes directly to storage

• One pound of fat equals around 3500 calories

• Carbohydrates – limited storage in the form of glycogen in muscle and liver
  

• Proteins used for tissue synthesis (e.g. muscle) and is not stored

• Proteins and carbohydrates can stimulate body to use them for fuel if necessary

• Balance consumption of these three nutrients

Basal Metabolism

• The minimum energy expended in a fasting state (12hours) to keep a resting, awake body alive in a warm, quiet environment

• 60-70% of the total energy used by the body to maintain basic bodily functions

• Does not include physical activity nor food digestion

• Amount of energy used for basal metabolism depends on lean body mass (body weight minus fat storage)

• Other influences:

  • Amount of body surface - increase in surface area, increase in heat release, increase in BMR
    

  • Gender - males have a higher BMR because they have higher testosterone and muscle mass
    

  • Body temperature - an increase in body temperature can increase BMR (increase energy demand, burn calories)
    

  • Thyroid hormone - increases BMR but starvation or low calories diets decrease TH production and decrease BMR!
    

  • Age - BMR decreases naturally over time because less growth and development of tissue
    

  • Nutritional state - 60-30-10 rule (therefore a balance of nutrients)
    

  • Health - fever, illness, and injury can increase BMR
    

  • Pregnancy - increases due to hormonal changes and growth and development of the fetus
    

  • Caffeine and tobacco use - increase cell metabolism BUT over time can have negative affects to body
    

• A lower energy intake decreases the basal metabolism by 10-20%

• Basal metabolism decreases 2% each decade past 30 (if this is true, then should we consume less calories as we age? Do most people do this?)
  

• Physical activity increase energy expenditure above and beyond basal energy needs by as much as 25-40%

Thermic Effect

• Increase in metabolism occurring during digestion, absorption, and metabolism of energy-yielding nutrients

• Represent 5-10% of energy consumed

Non-exercise Activity Thermogenesis (NEAT)

• Adaptive energy expended in heat production

• Increase in involuntary physical activity triggered by overeating

• Fidgeting, maintenance of muscle tone, and maintenance of body posture when not lying down

• Sedentary person uses 70-80% of energy for a combination of basal metabolism and the thermic effect – rest used for physical activity and non-exercise activity thermogenesis

Determination of Energy Use

• Direct calorimetry - method determining a body’s use by measuring heat that emanates from the body

• Indirect calorimetry – method to measure the energy used by the body by measuring oxygen uptake

• Energy Estimates:

  • Calculations:

    • Harris Benedict equations

    • Woman: BMR = 655 + (9.6 X weight in kilos) + (1.8 X height in cm) - (4.7 X age in years).

    • Man: BMR = 66 + (13.7 X weight in kilos) + (5 X height in cm) - (6.8 X age in years)

    • Note: 1 inch = 2.54 cm and 1 kilogram = 2.2 lbs

    • Total daily calorie needs:

      • Sedentary = BMR X 1.2

      • Lightly Active = BMR X 1.375

      • Moderately Active = BMR X 1.55

      • Very Active = BMR X 1.725

      • Extra Active = BMR X 1.9

    • Katch-McArdle equation (based on lean mass)

    • BMR = 370 + (21.6 X lean mass in kg)

    • Total calorie needs: BMR X activity factor (1.2,1.375,1.55, 1.725, and 1.9)

Hunger

• Desire to eat influenced by hunger and appetite

• Organs communicate via neuroendocrine factors

• Hypothalamus helps in regulating satiety

• Other factors that aid in regulating satiety:

• Control of feeding through body composition

• Leptin

  • The chemical called leptin has been identified in communicating the degree of “fatness” to the central nervous system

  • Gene used to cause synthesis of leptin has been isolate and called the ob gene

  • Leptin synthesized by fat cells

  • What does leptin do?

  • Inhibits the activity of neurons that synthesize neuropeptide Y (which initiates hunger and feeding)
    

  • Stimulates the activity of neurons that synthesize melanocyte stimulating hormone (MSH, which causes satiety)
    

  • Therefore, increase in leptin will then causes reduction of food intake

  • Leptin also influences thyroid gland activity which influences basal metabolism

• Ghrelin

  • Produced by cells of the stomach

  • Levels rise before meals and decreases after meals
  • Stimulates neuropeptide Y production which signals brain to feel hungry and increase the desire to consume food
  • Also promotes fat storage in adipose cells
    

  • Lack of sleep produces ghrelin which stimulates appetite and creates less leptin

• Other Hormones and chemicals regulating satiety

  • Endorphins (hormone) - chronic and increased levels of endorphins linked to decreases in body weight, conversely, inhibition of endorphin activity facilitates weight gain

  • Cholecystokinin (hormone) - (in conjunction with GI distension) reduces the rate at which food passes through the stomach

  • Serotonin (neurotransmitter) - rising levels of serotonin correlated with "feeling of satiety"

  • Histamine (neurotransmitter) - rising levels of histamine correlated with "feeling of saitety"

  • Insulin (hormone) - rising levels of insulin correlated with "feeling of saitety"

•  Circulating nutrients

  • Circulating saccharides, fatty acids, amino acids, and other energy-yielding nutrients cause brain to register satiety

Estimation of Healthy Weight

• Healthy body weight

• Factors influencing the healthy weight determination:

  • Hypertension, elevated LDL, family history (obesity, cardiovascular disease, certain cancers), pattern of fat distribution, elevated blood glucose

  • BMI

    • Body mass index – weight in kilograms divided by height (meter) squared

    • Note: 39.37 inches in one meter

    • BMI 20-25 (Normal)

    • BMI 25-30 (Overwieght)

    • BMI 30-35 (Obese), and
      

    • BMI 35-40+ (Severely/Morbidly Obese)

    • Value greater than 25 indicates a higher risk for obesity related health disorders

• Methods determining weight and fat content

  • Underwater weighing – method of estimating total body fat by weighing the individual on a standard scale and then weighing him or her again submerged in water – the difference between the two weights is used to estimate total body fat

  • Bioelectrical impedance – method to estimate total body fat that uses a low energy electrical current – the more fat storage the more impedance

• Diagnosing obesity

  • Upper-body (android) obesity – obesity in which fat is stored primarily in the abdomen area – greater than 40 inches in men and greater than 35 inches in women

  • Lower body (gynecoid, gynoid) obesity – obesity in which fat is stored primarily in the buttocks and thigh area

Obesity – Nature versus Nurture

• Nature

  • Genetic background accounts for about 70% of weight differences between people

  • Expression of the “ob” gene

  • Inherit body types

    • Ectomorphs – long and lean, high metabolic rate

    • Mesomorphs – broad shoulder narrow hips

    • Endomorphs – heavy boned carry more fat

  • Thrifty metabolisms - conserve energy and predispose individuals toward fat storage

  • Set point theory of weight maintenance

    • Weight is closely regulated by the body

    • Humans have predetermined body weight or body fat content

    • Hypothalamus monitors the fat content

    • The regulation of fat content is referred to as “set point”

• Nurture

  • Environmental factors also can influence the development of obesity

  • Prader-Willi syndrome – children have extreme appetite

Obesity and Weight loss

Obesity

• Long-term lifestyle changes

• Treat like a chronic disease

• Stimulate metabolism

• Do not cycle weight

• Only 5% of people who follow commercial diet programs lose weight and remain close to their weight

• One-third of weight lost during dieting is regained within 1 year of the end of the dietary restriction – all weight lost is regained within 3-5 yrs

• No rapid loss of weight (fat loss versus lean tissue loss)

• Professional treatment

• Very low calorie diets

• Gastric surgeries:  Restrictive (Gastric Banding) and By-pass

• Gastric Surgery Pro and Cons

• Pros

  • Rapid weight loss

  • Obesity related conditions improved (ex: diabetes)

• Cons

  • Need follow up surgery to correct complications (ex: abdominal hernias)

  • Develop nutritional deficiencies  

Weight loss

• Keys to weight loss

• Control of energy intake – loosing 1-2 pounds per week requires limiting energy intake to 1200 kcals per day for women and 1500 kcals per day for men

• Regular physical activity

• Behavior modification

  • Chain breaking – breaking the link between two or more behaviors that encourage overeating

  • Stimulus control – altering the environment to minimize the stimuli for eating

  • Cognitive restructuring - changing one’s frame of mind regarding eating

  • Contingency management – forming a plan of action to respond to a situation in which over eating is likely

  • Self monitoring – tracking foods eaten and conditions affecting eating

Popular Diets/Approaches used for Weight Loss

• Foods have a glycemic index (GI) which is its ability to increase blood glucose 2-3 hours after consumption
• Foods that have a high GI are metabolized quickly yet do not contribute much toward satiety whereas foods with a lower GI are processed slower and contribute greatly to satiety
• Question: what about mineral and other nutrient content?

Paleolithic or "Paleo" Diet

• Foods eaten that were only available and consumed by humans 10,000 years ago
• Consume lean protein, vegetables, fruits, nuts, and eggs
• Grains, legumes (e.g., beans), and dair products are excluded and not consumed
• Question: what about maintenance of wieght or nutrient balance?
  

Vegetarian Diet (see protein chapter notes)

South Beach Diet

• High protein diet in three phases
• Phase one - poultry, fish, turkey and shelfish as well as vegetables, nuts, eggs, and cheese
  
• Phase two - introduction of low GI foods (e.g., brown rice and whole wheat breads)
• Phase three - begin the planning of a well balanced diet

Raw Food Diet

• Intended not to loose weight but dramatically reduce saturated fats and sodium in the diet
• Multilevels or stages, each increasing the consumptiuon of raw vegetables and fruits
• Has side effects due to large change in diet in a small amount of time (e.g., headaches, nausea, fatigue, and cravings)

Atkins Diet

• Emphasizes the consumption of protein and fat
• Non-starchy vegetables (e.g., cantaloupes) and fruits (e.g., berries) are allowed
  
• Low calorie diet
  
• Large weight loss in short period of time

Others...

• Weight Watchers Diet
• Volumetrics Diet
• Jenny Craig Diet
• Slimfast Diet
• Grapefruit Diet
• Cabbage Soup Diet
• Sugar Busters Diet