Obesity and body-image concerns in adolescents — branching viva

Stem

The examiner will test whether you can reason through adolescent obesity classification under pressure, integrate body-image and mental-health screening, and defend a staged, weight-neutral management plan that escalates appropriately for severe disease. [1] [8]

Branch 1 — Classification and screening

Examiner: A 16-year-old plots above the 97th percentile on his growth chart. Is he obese, and what does that definition rest on? [1]

Strong answer: Yes. Obesity in the two-to-nineteen age group is defined as a BMI at or above the 95th percentile for age and sex on a CDC or WHO growth reference. His BMI above the 97th percentile clearly meets that. I would also calculate his percentage of the 95th percentile, because severe obesity is defined as at least 120 percent of the 95th percentile or an absolute BMI of at least 35, and that threshold drives escalation. [1] [7]

Examiner: What baseline investigations do you order? [2]

Strong answer: Fasting glucose or HbA1c for pre-diabetes and type 2 diabetes, a fasting lipid panel for dyslipidaemia, ALT for non-alcoholic fatty liver disease, and blood pressure with an appropriately sized cuff. I add an oral glucose tolerance test if fasting glucose is in the pre-diabetes range. I would also screen his mental health with the PHQ-A for depression and a tool such as the EAT-26 or SCOFF for disordered eating, because these are investigations in their own right and they change the management plan. [1] [10]

Branch 2 — Staged management

Examiner: Outline your staged management. [1]

Strong answer: Stage 1 is lifestyle for every patient: at least 60 minutes of moderate-to-vigorous activity daily, a sustainable healthy eating pattern, sleep optimisation, reduced recreational screen time, delivered with motivational interviewing and framed around health behaviours rather than weight. Stage 2 is structured multidisciplinary weight management. Stage 3 is anti-obesity pharmacotherapy, which I escalate to for severe obesity or when Stages 1 and 2 have not worked after three to six months. Stage 4 is metabolic and bariatric surgery at a specialist centre. A parallel body-image and mental-health track runs alongside every stage. [1]

Examiner: The family asks why he cannot simply eat less. How do you answer biologically? [2]

Strong answer: Obesity is a chronic disease of excess adiposity with a substantial polygenic basis, and the hypothalamic appetite-regulation systems that govern leptin and ghrelin signalling do not simply obey a person's intentions. Framing this as willpower is biologically inaccurate and it worsens outcomes, because it blames the young person for a regulated system set against them. That biological reality is also why severe obesity needs escalation beyond lifestyle, to pharmacotherapy and surgery. [2] [7]

Branch 3 — Severe obesity and surgery

Examiner: His BMI is 132 percent of the 95th percentile and he has impaired glucose tolerance. When do you consider surgery? [7]

Strong answer: He has severe obesity and a comorbidity, so he meets a common surgical threshold of a BMI at least 35 with a comorbidity, performed at an accredited specialist centre with lifelong follow-up and full adolescent and family informed consent. I would not leave severe obesity with diabetes risk on lifestyle and metformin alone, because the Teen-LABS data showed bariatric surgery achieved far better type 2 diabetes remission than medical therapy in severely obese adolescents. Before surgery I would optimise his comorbidities and mental health, and ensure he and his family understand the lifelong nutritional and adherence requirements. [7] [9]

Branch 4 — Mental health and body image

Examiner: His PHQ-A is positive and he reports years of weight-based bullying. How does this change management? [8]

Strong answer: The parallel mental-health track is core, not optional. I would assess his depression and suicide risk in detail, formulate a safety plan if needed, refer to psychology, and address the bullying with the school and family. The depression-obesity relationship is bidirectional — the Mannan meta-analysis shows adolescent depression predicts later obesity and vice versa — so untreated depression undermines every other intervention. Weight stigma itself worsens engagement, adherence, disordered eating and obesity trajectory, so I use weight-neutral, person-first language throughout and never make the scale the headline of the encounter. [8] [15]

Branch 5 — Atypical anorexia pitfall

Examiner: A different 14-year-old with a higher BMI is skipping meals and losing weight rapidly. Is this just successful dieting? [10]

Strong answer: No — I would be very concerned about atypical anorexia nervosa. A higher-weight adolescent who restricts intake and loses weight rapidly can have an eating disorder with the same medical danger as classic anorexia, including bradycardia, orthostatic changes and electrolyte disturbance. I would assess for physiological instability, and if any is present I escalate to an eating-disorder pathway, not a weight-loss pathway. The obesity treatment is held until eating-disorder stability is established. The lesson is that body-image distress and disordered eating do not map linearly onto BMI, and a positive screen in a higher-weight adolescent is never dismissed as expected. [10]

Examiner extras

• State the BMI percentile definition and the severe-obesity threshold precisely in your opening classification answer. [1] [7]
• Name all four baseline comorbidity screens — glucose, lipids, ALT, blood pressure — before moving on. [1]
• Always present lifestyle as the foundation, then justify escalation for severe disease. [1]
• Frame the disease as biological and regulated, never as willpower, when answering family questions. [2]
• Keep the parallel mental-health and body-image track visible in every management answer. [8] [15]