Obesity and metabolic syndrome

1Definition

Obesity is abnormal or excessive body fat that harms health. In practice it is screened with the body mass index: weight (kg) ÷ height (m)². Waist circumference shows abdominal (central) fat, which carries the most risk.

Metabolic syndrome is a cluster of risk factors (central obesity, raised BP, raised sugar, high triglycerides, low HDL) that together raise the risk of heart disease and type 2 diabetes.

2Classification and grading (3 marks in S21)

• Abdominal obesity (Indian cut-offs): waist 90 cm or more in men, 80 cm or more in women.
• A newer staged definition for Asian Indians was proposed in 2025 (stage 1 without and stage 2 with obesity-related disease or functional impairment). Use the cut-offs above in the exam and mention the proposal.

Metabolic syndrome: any 3 of 5 (harmonised definition)

1. Waist above the population cut-off (South Asians: 90 cm men, 80 cm women)
2. Triglycerides 150 mg/dL or more (or on treatment)
3. HDL below 40 mg/dL in men or 50 mg/dL in women (or on treatment)
4. BP 130/85 or more (or on treatment)
5. Fasting glucose 100 mg/dL or more (or on treatment)

3Causes and risk factors

• Energy intake higher than energy use: calorie-dense food, sugary drinks, fried snacks, large portions; sitting jobs, screen time, little walking.
• Genetics and family habits; South Asians store more fat centrally at lower BMI.
• Sleep loss, stress, some medicines (steroids, some antidepressants), hypothyroidism, Cushing's syndrome, polycystic ovary syndrome.

4Pathophysiology to impairments

• Excess abdominal fat releases fatty acids and inflammatory substances, causing insulin resistance, high BP and abnormal lipids: the route to diabetes and heart disease.
• A heavy chest wall and abdomen reduce lung volumes (especially lying flat) and raise the work of breathing; obstructive sleep apnoea and obesity hypoventilation can follow.
• Extra load on the knees, hips and back causes pain and osteoarthritis.
• Low fitness, heat intolerance, breathlessness and stigma reduce activity, so the cycle continues.

5Clinical features

• High BMI and waist; breathlessness on exertion; snoring and daytime sleepiness; joint pain; fatigue.
• Skin changes: dark velvety skin folds (acanthosis nigricans, a sign of insulin resistance), stretch marks.
• Low self-esteem, depression.

6Investigations

• BMI, waist circumference, waist-to-hip ratio; body fat (skinfolds, bioimpedance).
• Fasting glucose, HbA1c, lipid profile, liver tests (fatty liver), thyroid function.
• BP; sleep study if sleep apnoea is suspected.
• Fitness: 6MWT or step test; joint assessment.

7Medical and surgical management

• Lifestyle first: diet with a calorie deficit, physical activity, behaviour change, sleep.
• A loss of 5–10% of body weight already improves BP, sugar and lipids.
• Medicines (for example GLP-1 receptor agonists) in selected patients.
• Bariatric surgery for severe obesity with complications.

8Complications and prevention

• Type 2 diabetes, hypertension, coronary heart disease, stroke, fatty liver.
• Sleep apnoea, obesity hypoventilation; post-operative chest complications (higher risk after CABG and abdominal surgery).
• Osteoarthritis, back pain, falls, DVT, sternal wound problems after CABG.
• Some cancers; depression.

Prevention: regular activity, healthy diet, weight and waist checks, early treatment of risk factors.

9PT assessment

• Weight, height, BMI, waist; BP and resting HR (use a large cuff).
• Activity history, sitting time, diet habits, sleep, motivation and barriers.
• Joint pain and range; posture; balance.
• Fitness: 6MWT with Borg; strength (sit-to-stand test).
• Outcome measures: weight, waist, 6MWT, sit-to-stand, quality of life, step count.

10PT diagnosis by ICF

Obesity is usually written into another case's ICF as a personal factor and body-function impairment. Example from S21 (businessman, CABG 20 days ago, type 2 diabetes, BMI 32):

• Body function: class I obesity (WHO; obese by Indian criteria), insulin resistance, low fitness, heavy chest wall reducing lung volumes after surgery.
• Activity: walking distance and stairs limited by breathlessness and weight.
• Participation: business travel and social roles.
• Personal factors: diet habits, sitting job, stress.
• Environment: family meals, availability of safe walking space.

11Problem list and goals

• Short-term (4–6 weeks): walks 30 minutes on most days; sitting broken up every 30 minutes; keeps an activity and food diary.
• Long-term (6 months): loses 5–10% of body weight; waist reduced; 250 minutes or more of activity a week with resistance training twice a week; better 6MWT.

12PT management

• Type: low-impact aerobic activity first: brisk walking, cycling, swimming or water exercise, which spare the knees.
• Intensity: moderate (talk test; RPE 12–13), progressing to some vigorous work if fit.
• Build up: start with 10-minute bouts several times a day; add 5 minutes a week.
• Resistance training 2–3 days a week: keeps muscle while losing fat; improves insulin sensitivity.
• Lifestyle activity: stairs instead of lifts, walking to shops, breaking up sitting.
• Combine with a dietitian's plan; behaviour change (goal setting, self-monitoring, family support).

13Precautions

• Screen for heart disease, diabetes and sleep apnoea before vigorous exercise.
• Low-impact choices for painful knees and hips; good footwear.
• Heat intolerance: exercise in cooler hours, drink water.
• Use a large BP cuff; watch breathlessness; avoid lying flat for long.
• Chafing and skin-fold infections: breathable clothing.

14Education and lifestyle

• Aim for slow, steady loss of about 0.5 kg a week.
• Fewer sugary drinks, sweets, fried snacks and refined flour; more vegetables, pulses, fruit and whole grains; smaller portions.
• Move more through the day; sleep 7–8 hours; manage stress.
• Track weight and waist monthly.

15Prognosis

Even modest weight loss with regular activity lowers the risk of diabetes and heart disease. Fitness improves health even when weight changes little. Keeping weight off needs long-term activity.

16Exam corner

• S21 Q4(b), 3 marksGive grades of obesity (inside a Phase II cardiac rehab case with BMI 32).
• W24 Q1(a), 3 marksDefine metabolic syndrome.

Technique cards for this topic: exercise physiology.

Keywords to underline

BMI Indian cut-offs 23 and 25 waist 90/80 cm metabolic syndrome 3 of 5 150–250 min a week low-impact resistance training 5–10% weight loss