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How to investigate weight gain in an adult. ‘I’ve put on so much weight, doc’

Ramy H Bishay, Nic Kormas
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Abstract

Case scenarios are used in this section to educate doctors on the best approach to the diagnosis and management of patients with different endocrine problems. The appropriate selection of tests and correct interpretation of test results are discussed.

The global prevalence of people with a body mass index (BMI) over 30 kg/m2 has doubled, over 40 kg/m2 quadrupled, and over 50 kg/m2 increased fivefold.1-3 It is projected in Australia that if current rates of weight gain continue, normal-weight adults will constitute less than a third of the population by 2025, and the obesity prevalence will have increased by 65%.4

Weight, energy intake and expenditure are regulated by a complex integration of neurological, endocrine and gastrointestinal feedback mechanisms. They can also be influenced by psychological state, physical impairment, chronic disease, endocrinopathies and medications. Although genetics, development, promotion of sedentary lifestyles and easy access to energy-dense food are factors, adults with massive weight gain invariably have excess energy intake, and this is proportional to their weight.5-8 Patients are often embarrassed to disclose their complete dietary history or are genuinely unaware of how much energy they are consuming, in which case they believe their weight gain is caused by a lack of physical activity. Many also believe that short periods of exercise negate any increase in energy intake, and so cannot understand why they are putting on weight.

Although this article discusses the challenges in managing patients with massive weight gain with resultant morbid obesity, it is still relevant to the assessment of patients presenting to their primary care physicians with modest weight gain (i.e. 5 to 10 kg). 

Case scenario

Virginia, a 64-year-old woman presents to her general practitioner with progressive weight gain spanning two decades. She is severely obese (obese class III, 141.5 kg, body mass index [BMI] 57 kg/m2; Table 1)9 and has obesity-related complications including obstructive sleep apnoea (OSA) requiring continuous positive air pressure (CPAP) treatment, impaired fasting glucose, hypertension (160/90 mmHg), nonalcoholic fatty liver disease on ultrasound, and osteoarthritis affecting her spine, hips and knees. She is a nonsmoker, consumes minimal alcohol and has a family history of obesity (her parents and siblings). She moves with difficulty and requires a forearm support frame when she does house cleaning. 

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Virginia would like to lose weight but does not think she can achieve this as she cannot exercise. She believes being unable to exercise has caused her weight gain. 

 

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What is the first step in managing this patient?

A more detailed history reveals that Virginia takes irbesartan 150 mg daily, amlodipine 5 mg twice a day and mirtazapine 30 mg daily for depression, as well as simple analgesia for osteoarthritis. Use of weight-promoting medications (e.g. mirtazapine) should be sought, and ceased or substituted if possible (Table 2).10 

Use of a brief, clinically useful dietary questionnaire developed by the authors (acronym SPEL, see the Box) showed that Virginia consumes large portions as she enjoys feeling ‘full’ and energy dense food as she finds it tasty. She also snacks frequently as she feels it helps with her pain relief. In summary, her weight gain is mainly the result of increased energy consumption coupled with deteriorating mobility. 

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© avid creative/istockphoto. MODEL USED FOR ILLUSTRATIVE PURPOSES ONLY.
© avid creative/istockphoto. MODEL USED FOR ILLUSTRATIVE PURPOSES ONLY.
Dr Bishay is an Advanced Trainee in Endocrinology at Concord Repatriation General Hospital and an honorary associate of the Sydney Medical School, University of Sydney. Dr Kormas is Head of the Metabolic Rehabilitation Programs at Concord Repatriation General and Camden Hospitals in Sydney, NSW; Senior Staff Specialist Endocrinologist at these hospitals; and Co-ordinator of the publicly funded bariatric program of the Sydney Local Health District. SERIES EDITOR: Dr Bernard Champion, BEc, MB BS, BSc(Med)(Hon 1), FRACP, MMedEd, is a Lecturer at Sydney Medical School Nepean and The University of Sydney; and Head of Department – Endocrinology and Diabetes, Nepean Blue Mountains Local Health District, Penrith, NSW.