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Obesity ( Adults )

Overweight and obesity are defined as abnormal or excessive fat accumulation that presents a risk to health ( WHO )


Major health hazard in the 21st century – a serious global epidemic ( Globesity ) Relatively rare before the 1960s Worldwide obesity has nearly tripled since 1975 WHO reports that
○ in 2016 nearly 1.6 billion adults , 18 yrs and over were overweight
○ now most of the world’s population lives in countries where overweight and obesity kills more people than underweight
○ it affects both adults and children and in 2019 over 340 million children and adolescents aged 5-19 were overweight and obese Most western countries have seen an increase in obesity but it has particularly sky-rocketed in the US & UK The problem is now not limited to high income countries only and has seen a dramatic rise in low and middle income countries – particularly in urban areas.


Classification -
Body fat measurement can be difficult and two common methods to assess obesity are
 Body Mass Index ( BMI ) which quantifies the relationship between height and weight and is calculated as weight ( kg ) / height squared (m2 ) BMI is not a measure of adiposity but is simple to use in health settings and epidemiological surveys. It is highly correlated with the percentage of body fat in population basis.
 Waist circumference -large waist circumference > 40 inch in men and > 35 inch in women are considered as independent risk factors for obesity and increased morbidity 
( ↑ intra-abdominal fat is associated with greater morbidity than peripheral fat accumulation )


What happens – Pathogenesis – complex , multifaceted aetiology and pathophysiologies An imbalance between energy expenditure and supply ( positive energy balance ) due to 
○ increased energy intake
○ low physical activity
○ reduced energy expenditure Factors which play a role include environmental , sociocultural , physiological , medical , behavioral , genetic , epigenetic ( study of how behaviors and environment can cause changes that affect how genes work ) Obesogenic changes linked to economic growth as Dietary factors ( overconsumption of calorie dense food which is abundant , inexpensive and often nutrient-poor ) ,sedentary lifestyle , increased consumption of saturated fats and carbohydrates combined with decreased vegetable intake and low physical activity levels , mechanised transportation , urbanization Genetic predisposition – more than 140 genetic chromosomal regions related to obesity have been found and a seven-fold greater lifetime risk of suffering with extreme obesity has been demonstrated when one of the parents is obese Secondary causes include 
○ Cushing’s disease / syndrome
○ Hypothyroidism
○ Hypothalamic lesions


Why important –A major risk factor for non-communicable diseases ( NCD’s )
○ examples of NCDs include CV disease , certain cancers and diabetes
○ estimated to decrease the life expectancy by about 5-20 yrs depending upon the severity of the condition and comorbid disorders
○ risks of numerous other detrimental conditions also increase with obesity as depression , hyperlipidemia , gallbladder disease , obstructive sleep apnoea , osteoarthritis ,steatohepatitis , gastroesophageal reflux , PCOS , infertility , Alzheimer’s disease Obesity continues to be under-diagnosed in clinical practice and it is estimated that in the US < than 30 % of adults with obesity receive attention when they visit primary care Crucial public health concern – significant societal costs and healthcare expenditure A BMI of 30 or more is associated with significantly ↑↑ ed rates of morbidity as T2DM , CAD and of mortality Worldwide 44 % of diabetes burden , 23 % of IHD and 7 % to 41 % of certain cancers are attributable to excess weight


Diabetes -well known association ( diabesity ) risk of developing T2 diabetes ↑ by 20 % for each 1 kg/m2 increase in the BMI ( about 80 % of those with diabetes are over weight / obese due to beta cell failure , insulin resistance ADA recommends test for type 2 diabetes and risk of future diabetes in asymptomatic people ≥ 45 if they are overweight/ obese and regardless of age if severely obese


CVD -associated with metabolic syndrome metabolic syndrome is associated with 
○ central obesity 
○ ↑↑ triglycerides & low HDL
○ hypertension
○ impaired fasting glucose ↑↑ in cardiac output and risk of heart failure ↑↑ risk atrial fibrillation & hypertension


Respiratory -obesity hypoventilation syndrome – risk of hypercapnic respiratory failure obstructive sleep apnoea – sleep disordered breathing is common altered lung compliance and respiratory control ( lung function tests are impaired particularly ↓↓ in functional residual capacity 
( FRC ) and expiratory reserve volumes BMI has an independent positive relation with asthma likely due to impact of adipose tissue on the chest wall – restrictive lung disease and SOB is common in obese patients.


Kidneys -↑↑ es the risk factors for CKD ( e.g diabetes , hypertension ) high BMI is one of the strongest risk factors for new onset CKD obese patients often have ↑ albumin excretion rates ↑ incidence obesity related glomerulopathy risk factor for nephrolithiasis.


Liver -increased risk of liver disease risk factor for non-alcoholic fatty liver disease and its progression in a series observed in liver unit


Sexual dysfunction -erectile dysfunction subfertility.


Cancer -association between obesity and cancer is quite secure in human populations cancers associated with obesity include breast cancer in post-menopausal women , colon cancer ( particularly in men ) , endometrial , eosophageal adenocarcinoma , gall bladder and renal cancers


Pregnancy-adverse neonatal outcomes increased rate of C section and morbidity for the women.


Assessment -Discuss the issue Be ready to explore the disease and advice about the harms of obesity and the benefits of weight loss Willingness and motivation Diet Eating behaviours Physical activity Previous attempts at weight loss Obesity related problems Underlying causes Co-morbidities for e.g
○ diabetes
○ hypertension
○ osteoarthritis
○ dyslipidemia
○ sleep apnoea Discuss results from tests done Family history – over weight , obesity and comorbidities Psychological and psychosocial issues Medications and medical problems


Tier system – NHS England.


Lifestyle -cornerstone of obesity management multicomponent interventions several guidelines recommend use of multi-disciplinary teams to manage the condition on the lines of a chronic disease


behavioural interventions form part of most guidelines NICE recommends behavioural interventions with the support of an appropriately trained professional


Physical activity -encourage to ↑ physical activity level even if it does not lead to wt loss advice to undertake 45-60 mins of moderate intensity activity / day
if they are not able to reduce energy intake obese people who have lost weight may need 60-90 mins of 
activity / day to avoid regaining weight


Dietary -main approach is to ensure that total energy intake is less than energy expenditure & create a negative energy balance how this is achieved may vary from diet to diet


Pharmacological -once dietary , exercise and behavioural approaches have been
started and evaluated -> and target weight loss is not met or plateaued should be used as an adjunct to lifestyle measures Orlistat – only current licensed medication in the UK BNF recommends use in obesity in conjunction with a mildly hypocaloric diet with
○ BMI of 30 or more
○ BMI of 28 or more + other risk factors such as T2DM , hypertension or ↑ cholesterol reversible active -site inhibitor of GI lipases -prevents dietary fat from being hydrolyzed and absorbed at the recommended dose it inhibits dietary fat reabsorption 
by about 30 % exercise caution when prescribing for people with
○ chronic malabsorption syndrome or cholestasis
○ breast feeding women
○ people with CKD some fat soluble vitamins may not be absorbed advice is to take multivitamins or/and a diet rich in fruit and vegetable.


Referral -further assessment is needed to explore the underlying cause of obesity further support is needed due to complex underlying needs ( for e.g people with learning disability ) failure of conventional treatment drug treatment is being considered for a person with BMI > 50 kg / m2 specialist interventions like a very low calorie diet is needed for surgical intervention.


Surgical -Referral for bariatric surgery is suggested by NICE if the following
 criteria is met
 BMI of 40 kg/m2 or more BMI between 35 and 40 + significant disease for e.g type 2 diabetes or hypertension where weight loss would be beneficial Non-surgical interventions have failed The person has received or is currently receiving tier -3 service Person is deemed fit for anaesthesia and surgery ( be mindful of the 
fact that the pre-anaesthetic clinics would assess for fitness ) The person commits to the need for long term f/u.

Patient information

NHS on obesity treatment

NHS inform Scot on obesity

Bariatric surgery information from The American Society for Metabolic and Bariatric Surgery

NPS medicine wise on Orlistat for patients

Patient group HOOP – helping overcome obesity problems

British Nutrition Foundation

Information for Healthcare Professionals

RCGP toolkit on obesity- a useful collection of resources

British Psychological Society – understanding obesity a 61 page information for HCPs





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  7. Obesity: identification, assessment and management Clinical guideline [CG189]Published date: 

  8. Kovesdy, Csaba P et al. “Obesity and Kidney Disease: Hidden Consequences of the Epidemic.” Canadian journal of kidney health and disease vol. 4 2054358117698669. 8 Mar. 2017, doi:10.1177/2054358117698669
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  14. Obesity and overweight WHO Obesity and overweight (
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  16. Obesity CKS Obesity | Health topics A to Z | CKS | NICEHealth vector icons used courtesy of


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