Presentation on theme: "Welcome to Session on Obesity Meera Kaur, PhD, RD Assistant Professor Department of Family Medicine Faculty of Medicine email@example.com http://home.cc.umanitoba.ca/~kaur."— Presentation transcript:
1 Welcome to Session on Obesity Meera Kaur, PhD, RD Assistant Professor Department of Family Medicine Faculty of Medicine
2 Outline Learning objectives Introduction Classification and diagnosis 2Learning objectivesIntroductionClassification and diagnosisObesity trendAdipose tissue, adiposity, hypertrophy and hyperplasiaEnergy balanceRegulation of body weightRegulation of food intake and body weightRegulatory factors in feeding and adipositySound weight loss programConclusionsQuestions and answers
3 Learning Objectives To understand 3Learning ObjectivesTo understandthe physiological and metabolic perspectives of obesity/overweight, andthe regulation of body weight with special reference to:Regulatory factors involved in feeding and adiposity
4 4IntroductionObesity is the disorder of body composition defined by a relative or absolute excess of body fat.The WHO and NHLBI have classified obesity as an epidemicIn 2002, ~64% Americans overweight; 32% obese16% or 9 million kids were overweightThus, a trend towards an ever-fatter AmericaBy 2009, 70% of American expected to be overweight or obeseObesity contributes to +300,000 deaths a yearFrom a global perspective, the increase in the prevalence of obesity is alarming
5 Classification and Diagnosis 5Classification and DiagnosisClassificationBMI (kg/m2)Risk of Co-morbiditiesUnderweight<18.5increased risk in other areasDesirableAverageOverweightMildly IncreasedObese>30.0Class I ObesityModerateClass II ObesityClass III Obesity>40.0SevereVery severe
6 Classification for Children (<2 Years) 6Classification for Children (<2 Years)BMI StatusNormal weight for height 10th-90th percentileAt risk for overweight 85th-95th percentileOverweight >95 percentile(Centre for Disease Control and Prevention, 2005)
7 Assessing Obesity Waist circumference at level of iliac crest 7Assessing ObesityWaist circumference at level of iliac crestAbove 40 inches for men and 35 inches for women are indicative of health risk.Waist-to-hip ratio: Circumference of the waist at the level of L3 divided by the circumference of the hip at the largest area of the gluteal region. (Helps identify central or android obesity.)For men waist-to-hip ratio > 1For women waist-to-hip ratio > 0.85
8 Obesity Trends in US Adults 81991199319951998< 10%10% to 15%> 15%AH, et al. JAMA. 1999
10 Obesity Trends in US Adults, 2004 10No Data <10% %–14% 15%–19% %–24% ≥25%
11 Adipose Tissue, Adipocytes, Hypertrophy and Hyperplasia 11Adipose Tissue, Adipocytes, Hypertrophy and HyperplasiaAdipose tissueWhite: energy, cushion, insulationBrown: Key regulator of energy expenditureAdipocytesstore 80-90% fat as tryglycerideHypertrophy adipose tissue due to enlarged adipocytesHyperplasia adipose tissue due to number of adipocytes
12 Juvenile-Onset Obesity 12Juvenile-Onset ObesityDevelops in infancy or childhoodIncrease in the number of adipose cellsAdipose cells have long life span and need to store fatMakes it difficult to lose the fat (weight loss)Causespoor dietary patternslack of physical activity43% of adolescents watch 2 hours or more of TV/day
13 Adult-Onset Obesity Develops in adulthood 13Adult-Onset ObesityDevelops in adulthoodFewer (number of) adipose cellsThese adipose cells are larger (stores excess amount of fat)If weight gain continues, the number of adipose cells can increase
14 Regulation of Body Weight 14Regulation of Body WeightShort-term regulation is governed by:Hunger (postabsorptive), appetite and satiety (postprandial)physical trigger for hunger > satietyLong-term regulation is governed by:feedback mechanism– adipocytokines (signaling protein is released from the adipose mass when normal body composition is disturbed. This mechanism plays a greater role in younger persons than older adults.
15 15Set-Point TheoryFat storage in nonobase adult is regulated to preserve the specific weight.deliberate effort to starve or overfeed are followed by a rapid return to original body weight (set-point).if set-point theory is true, some form of obesity could be due to the abnormally established set-point.Can we establish a new settling-point vs. Set-point to treat obesity?However, data are not conclusive in this area. We need to do more research.
17 17Energy Balance…State in which energy intake, in the form of food and /or alcohol, matches the energy expended, primarily through basal metabolism and physical activityPositive energy balanceEnergy intake > energy expendedResults in weight gainNegative energy balanceEnergy intake < energyResults in weight loss
19 Regulation of Energy Intake and Body Weight 19Regulation of Energy Intake and Body WeightFactors that regulate energy intake and body weights are:Dietary thermogenesis and the Thermic Effect of Foods (TEF)/Specific Dynamic Action (SDA) of foodsResting/Basal Metabolic Rate (RMR)/(BMR)Energy expended in voluntary activityRegulatory neurotransmitters and hormones
20 Thermic Effect of Foods 20Thermic Effect of FoodsEnergy used to digest, absorb, and metabolize food nutrients“Sales tax” of total energy consumed~5-10% above the total energy consumedTEF is higher for CHO and protein than fatLess energy is used to transfer dietary fat into adipose storesMeal size, meal composition, previous meal, insulin resistance, physical activity and aging influence the TEF.Aerobic exercise the TEF
21 Resting Metabolic Rate (RMR) 21Resting Metabolic Rate (RMR)RMR explains 60-70% of Total Energy expenditure (TEE). When body is deprived of energyRMR adapts to conserve energy by dropping rapidly (up to 15% in two weeks).RMR declines with ageDuring undernutrition, abnormalities in lipolysis may cause insulin resistance affecting RMRThe regulation of free fatty acid availability is an important area of research related to the RMR.
22 Activity Thermogenesis (AT) 22Activity Thermogenesis (AT)Energy expended in voluntary activity – activity thermogenesis (AT) is the most important component of TEE (15-30% normally). Therefore, AT should be when energy is not restricted.RMR and Fat free mass (FFM) decrease with age. Hence adjustment between energy intake and AT should be adjusted for preserving normal weight.All activity counts including nonexcercise activity thermogenesis (NEAT).To reverse obesity standing and ambulatory time should be promoted at least 2.5 hours/day.
24 Ultimate Energy Balance 24Ultimate Energy BalanceTEFREENEATPhysical activityDietaryIntake
25 Macronutrients and Fat Storage 25Macronutrients and Fat StorageBody prefers to use CHO as energy sourceOnly excess intake of CHO and protein will be turned into fatFat will remain as fat for storagePhysical activity encourages the burning of dietary fat (Beta-oxidation)High CHO diet decreases Beta-oxidationMost endurance athletes burn fatty acids for energy
26 Fat Storage Fat Carbohydrates 26Fat StorageFatMost fat is stored directly into adipose tissueBody has ability to store fat (as fat)CarbohydratesLimited CHO can be stored as glycogen Most CHO is used as a energy sourceExcessive CHO will be synthesized into fat (for storage)
27 Protein and Fat Storage 27Protein and Fat StorageProtein is primarily used for tissue synthesisAdults generally consume more protein than needed for tissue synthesisExcess protein is used as a energy sourceSome protein will be synthesized into fat (for storage)
28 Regulatory Factors in Feeding and Adiposity 28Regulatory Factors in Feeding and AdiposityBrain NeurotransmittersGut hormonesOther hormones
29 Brain Neurotransmitters 29Brain NeurotransmittersNorepinephrine and DopamineReleased by symphathetic nervous system (SNS)Fasting & starvation SNS activity, epinephrine that govern feeding behaviour and subatrate mobilizationDopaminnergic pathway in the brain play a role in reinforcement properties of foodds.Serotonin In serotonin leads to carbohydrate appetite.Corticotrophin-releasing Factor (CRF)CRF is a potent anorexic agent and weakens the feeding response produced by norepinephrine and neuropeptide Y.CRF is released during exercise.
30 Gut Hormones… Incretins is a G-I peptide Cholecystokinin (CCK) 30Gut Hormones…Incretins is a G-I peptide insulin release after eating , even before blood glucose level is elevated. Serotonin is a G-I peptideCholecystokinin (CCK)At brain level inhibits food intake. Stimulates pancreatic enzymesBombesin Food intake and enhances the release of CCK.EnterostatinPart of pancreatic lipase; satiety following fat consumption
31 Gut Hormones Adiponectin - Adipocytokine secreted by adipose tissue 31Adiponectin - Adipocytokine secreted by adipose tissueLevel of this hormone is inversely related to BMI. Plays role in metabolic disorders.Glucagon causes hypoglycemiaGlucagon-like-peptide-1 (GLP-1)Released in presence of glucose rich food, delays gastric emptying time and promote satiety.Leptin is an adipocytokine and regulates appetite.In obesity it loses the ability to inhibit energy intake.Resistin - An adipocytokine that antagonizes insulin actionGhrelin – Produced in stomach and stimulate hunger.Peotide YY-3-36 (PYY ) is secreted in small bowel in response to foods.
32 Other Hormones32Thyroid hormone – Modulates the tissue responsiveness to the catecholamines secreted by SNS. A in thyroid hormone lpwers the SNS activity and adaptive thermogenesis.Vispatin - An adipocytokine protein that has an insulin-like-effect. Plasma level with adiposity and insulin resistance.Adrenomedullin - A new peptide secreted by adipocytesas a result of inflammatory process
33 Satiety Regulator The hypothalamus Sympathetic nervous system 33Satiety RegulatorThe hypothalamusWhen feeding cells are stimulated, they signal us to eatWhen satiety cells are stimulated, they signal us to stop eatingSympathetic nervous systemWhen activity increases, it signals us to stop eatingWhen activity decreases, it signals us to eat
34 Influences of Satiety… 34Influences of Satiety…
36 What it Takes to Lose a Pound 36What it Takes to Lose a PoundBody fat contains 3500 kcal per poundFat storage (body fat plus supporting lean tissues) contains 2700 kcal per poundMust have an energy deficit of kcal to lose a pound per week
37 37Do the MathTo lose one pound, you must create a deficit of kcalSo to lose a pound in 1 week (7 days), try cutting back on your kcal intake and increase physical activity so that you create a deficit of kcal per day- 500 kcal x 7 days = kcal = 1 pound of weight lossday week in 1 week
38 Sound Weight Loss Program 38Sound Weight Loss ProgramMeets nutritional needs, except for kcalSlow & steady weight lossAdapted to individuals’ habits and tastesContains enough kcal to minimize hunger and fatigueContains common foodsFit into any social situationChange eating problems/habitsImproves overall healthSee a physician before starting
39 Summary and Conclusion 39Summary and ConclusionTo treat obesity and/or develop an effective weight loss program, understanding ofthe physiological and metabolic perspectives of obesity/overweight is importantthe regulation of body weight with special reference to:Regulatory factors involved in feeding and adiposity is crucialEnergy balance is the key pointTeam approach is important in developing a sustainable weight loss program
40 Thank you for gracing the session! Any question?