COURSE GUIDE - International Association for the Study of Obesity

Speaker Presentation SummariesPhilip JamesEnergy balance and body compositionEnergy balance is understood by few as it implies that the multiplefactors affecting energy intake in some way balance all the differentcomponents of energy expenditure. Energy balance for simplicityis considered on a daily basis but the evidence suggest that weall oscillate from day to day, month to month in our net energystorage but traditionally over a year the body mass of energy didnot change. Physiological storage of energy occurs during growth,pregnancy, recovery from illness and more energy flows throughthe body in lactating mothers. Now in modern times adults tend toput on weight by about 0.5- 1.0kg per year which corresponds to 3,850 to 7,700kcal in total. If an adult eats 2,5000kcal /d on averagethis means the average rate of accumulation is 10-20 kcal/day. Thisis impossible to measure either in terms of intake or expenditureparticularly as in young premenstrual women there is a cycling offood intake and basal metabolism throughout the menstrual cycleamounting to a 10-20% variation.Energy requirements have to be assessed by estimating energyexpenditure as these are crudely more readily estimated by ourunderstanding of energy expenditure. Most food intake measurementsare very unreliable. The basal metabolic rate is estimated fromequations based on a global data base and the cost of eating foodand processing it puts up metabolism by 10-20% with some evidencethat this is adaptable to the state of energy balance. We now estimatelevels of minute by minute physical activity as a ratio of BMR, knownas METS by the sports physiologists but the overall physical activitylevel (PAL) on a daily basis is now taken as the gold standard forassessing the overall demand of the body for food.Measurements of body composition used to rely on underwaterweighting, skin-fold measurements, K 40 measurements or bydifferent scanning techniques which can either assess lean tissuemass, bone mass, or individual organs. Basal metabolic rate dependson the mass of lean tissues and the relative proportions of moreactive visceral tissue but also the much lower activity (at rest) muscle.Women put on more fat and gave less lean tissue and proportionatelyless muscle after puberty and are usually shorter than men. Thereforewomen have an energy requirement which is about 80% of men’s.There is a very complex system for controlling energy intake but recentlyit has become apparent that spontaneous (unconscious) movementand activity is individually very variable in response to changes inenergy balance with a probable genetic variation if the degree to whichwe adjust our spontaneous movement to changes in food intake. Thisseems to be an important explanation for why carefully overfed adultsdiffer remarkable in the degree of consequent weight gain.Slimming immediately induces a TSH induced fall of as much as15% in BMR starting within 48hrs (before significant weight loss) andreaches the maximum per Kg fat free mass(FFM ) within 2 weeks.Thereafter the decline in BMR is proportional to lean FFM loss sothat when weight destabilizes say 10kg lower the body’s energyneeds are permanently less unless physical activity is permanentlyincreased. The difference is estimated to amount to 200-300kcal/d.This accounts for the stabilisation of weight and the impossibility ofremaining at a lower weight unless permanent reduction sin foodintake or increases in physical activity are induced.Arya SharmaAetiological approach to the assessment of obesityObesity is characterized by the accumulation of excess bodyfat and can be conceptualized as the physical manifestationof chronic energy excess. Using the analogy of oedema, theconsequence of positive fluid balance or fluid retention, obesitycan be seen as the consequence of positive energy balance orcalorie ‘retention’. Just as the assessment of oedema requires acomprehensive assessment of factors related to fluid balance,the assessment of obesity requires a systematic assessmentof factors potentially affecting energy intake, metabolism andexpenditure. Rather than just identifying and describing abehaviour (‘this patient eats too much’), clinicians should seek toidentify the determinants of this behaviour (‘why, does this patienteat too much?’). This presentation will discuss an aetiologicalframework for the systematic assessment of the socio-cultural,biomedical, psychological and iatrogenic factors that influenceenergy input, metabolism and expenditure. The frameworkconsiders factors that affect metabolism (age, sex, genetics,neuroendocrine factors, sarcopenia, metabolically active fat,medications, prior weight loss), energy intake (socio-culturalfactors, mindless eating, physical hunger, emotional eating, mentalhealth, medications) and activity (socio-cultural factors, physicaland emotional barriers, medications). The clinical application ofthis framework can help clinicians systematically assess, identifyand thereby address the aetiological determinants of positiveenergy balance resulting in more effective obesity preventionand management.FRIDAY 29TH JULY 2011David HaslamCommissioning obesity care and weight managementservicesThe commissioning of services for obese and overweightindividuals is shrouded in controversy and misperceptions.Management of the obese individuals is not merely confined tocounting the number of Kg lost, but a recognition that identificationand screening has occurred, co-morbid diseases have beenrecognised and successfully managed. The cost-effectiveness ofobesity management, upon which commissioning centres, shouldtake these aspects more into account, enabling bariatric surgeryas a case in point, but also nutrition and lifestyle interventions, tobe much more broadly available to those who need them most.Robin HarbourHow do you judge the quality of evidenceThe basis on which evidence-based recommendations are relatedto evidence is changing, and the process of relating evidence torecommendations is becoming more sophisticated. This sessionwill outline the Grading of Recommendations Assessment,21