After reading this note you will be able to define obesity and metabolic syndrome, list the local aetiologies, describe the key pathophysiological steps and recognise the essential clinical findings. Always verify drug choices, doses and local protocols against the Kenya MoH guideline and your hospital formulary.
Definition
- Obesity: excess body fat that impairs health, usually expressed as a body‑mass index (BMI) ≥ 30 kg/m² in adults; for Kenyan adults BMI ≥ 30 is the cut‑off, with waist‑circumference > 102 cm (men) or > 88 cm (women) indicating central adiposity.
- Metabolic Syndrome (MetS): a cluster of inter‑related cardiometabolic risk factors. In Kenya the most used criteria are the IDF definition: central obesity (mandatory) plus any two of the following – elevated triglycerides, reduced HDL‑cholesterol, raised blood pressure, or impaired fasting glucose.
Anatomy and physiology you need
| Structure | Relevance to obesity/MetS |
|---|---|
| Adipose tissue (subcutaneous & visceral) | Stores triglycerides; visceral fat releases free fatty acids & adipokines that drive insulin resistance |
| Hypothalamus (ARC, PVN) | Integrates leptin & insulin signals to regulate appetite & energy expenditure |
| Pancreas (β‑cells) | Secretes insulin; chronic insulin resistance leads to hyperinsulinaemia and β‑cell stress |
| Liver | Site of de‑novo lipogenesis; hepatic insulin resistance causes ↑ VLDL, ↑ TG |
| Muscle | Major glucose sink; insulin resistance reduces glucose uptake |
| Endothelium | Exposed to inflammatory cytokines from adipose tissue → atherogenesis |
Causes and risk factors
| Category | Specific factors in Kenya |
|---|---|
| Lifestyle | High‑calorie western‑type diets, sugary drinks, low fruit/veg intake, sedentary occupations, urban migration |
| Socio‑economic | Poverty limiting access to healthy foods, food insecurity leading to “feast‑famine” cycles |
| Genetic/ethnic | African ancestry predisposes to central fat deposition; family history of obesity/diabetes |
| Infectious | HIV (ART‑associated lipodystrophy, chronic inflammation), TB (post‑treatment weight gain), malaria (repeated episodes may alter metabolism), rheumatic fever (steroid therapy), sickle cell disease (chronic anemia, steroid use) |
| Medications | Second‑generation antipsychotics, glucocorticoids, some antiretrovirals, protease inhibitors |
| Endocrine | Hypothyroidism, Cushing’s syndrome, polycystic ovary syndrome |
| Psychosocial | Depression, stress, cultural perceptions of “larger body” as health |
Pathophysiology
- Energy imbalance → chronic excess caloric intake + reduced expenditure → ↑ adipocyte size (hypertrophy)
- Adipocyte hypertrophy → hypoxia → secretion of pro‑inflammatory cytokines (TNF‑α, IL‑6) & ↓ adiponectin
- Inflammation & adipokine shift → systemic insulin resistance (muscle, liver)
- Insulin resistance → compensatory hyperinsulinaemia → ↑ hepatic VLDL production → hypertriglyceridaemia & ↓ HDL
- Visceral fat expansion → free fatty acids delivered to liver → hepatic steatosis → further insulin resistance
- Hyperinsulinaemia + SNS activation → sodium retention & vascular smooth‑muscle growth → hypertension
- Impaired glucose uptake → fasting hyperglycaemia → β‑cell exhaustion → type 2 diabetes mellitus
Arrows illustrate the cascade: Energy excess → Adipocyte hypertrophy → Inflammation → Insulin resistance → Dyslipidaemia + Hypertension + Hyperglycaemia → Metabolic syndrome.
Clinical features
| History domain | Key questions | Why it matters |
|---|---|---|
| Weight trajectory | “When did you first notice weight gain? How fast has it progressed?” | Rapid rise suggests endocrine or medication effect; gradual rise points to lifestyle or genetic predisposition. |
| Distribution of fat | “Do you carry weight around the waist, hips, or elsewhere?” | Central (visceral) adiposity is the hallmark of metabolic syndrome and predicts cardiovascular risk. |
| Appetite & diet | “What do you eat daily? Any binge episodes? Use of sugary drinks or high‑fat foods?” | Excess caloric intake and poor diet quality are modifiable drivers. |
| Physical activity | “How many days per week do you walk, run, or do farm work? Any sedentary occupations?” | Low energy expenditure reinforces weight gain and insulin resistance. |
| Medications & supplements | “Are you on steroids, antiretrovirals, protease inhibitors, antipsychotics, or herbal remedies?” | Many drugs (e.g., ART, steroids) cause lipodystrophy or weight gain in Kenyan patients. |
| Co‑morbid infections | “History of TB, HIV, malaria, sickle‑cell crises, rheumatic fever?” | Chronic infections can alter metabolism, cause steroid use, or lead to secondary obesity (e.g., HIV‑associated lipodystrophy). |
| Family history | “Any close relatives with diabetes, hypertension, dyslipidaemia, early heart disease?” | Genetic predisposition to insulin resistance and dyslipidaemia. |
| Menstrual/reproductive history (women) | “Irregular periods, polycystic ovary syndrome symptoms?” | PCOS is a common cause of central obesity and insulin resistance. |
| Sleep & stress | “Do you have sleep apnoea, shift work, chronic stress?” | Sleep deprivation and stress hormones worsen insulin resistance. |
| Symptoms of complications | “Chest pain, dyspnoea, leg swelling, polyuria, nocturia, visual changes, skin changes?” | Early detection of cardiovascular, renal, or hepatic sequelae. |
| Examination element | What to look for | Pathophysiological explanation |
|---|---|---|
| BMI & waist circumference | Measure weight, height, waist at midpoint between iliac crest and rib cage | BMI quantifies overall adiposity; waist >94 cm (men) or >80 cm (women) signals visceral fat. |
| Hip circumference & waist‑to‑hip ratio | Hip measurement, calculate ratio | High ratio (>0.90 men, >0.85 women) confirms central obesity. |
| Blood pressure (both arms) | Systolic/diastolic reading | Hypertension is a core component of metabolic syndrome, driven by insulin resistance and sympathetic activation. |
| Skin inspection | Acanthosis nigricans, striae, xanthelasma, skin tags | Hyperinsulinaemia stimulates keratinocyte proliferation (acanthosis) and lipid deposition (xanthelasma). |
| Neck & upper back | “Buffalo hump”, cervical fat pad | Corticosteroid excess or HIV‑associated lipodystrophy. |
| Peripheral pulses & edema | Check for peripheral vascular disease, fluid overload | Hypertension and dyslipidaemia predispose to atherosclerosis; heart failure may cause edema. |
| Hepatomegaly & liver edge | Palpate liver, assess for fatty infiltration | Non‑alcoholic fatty liver disease (NAFLD) is common in obesity. |
| Thyroid exam | Size, nodules, bruit | Excludes hypothyroidism, a reversible cause of weight gain. |
| Musculoskeletal | Joint line tenderness, limited ROM | Obesity stresses weight‑bearing joints, may reveal early osteoarthritis. |
| Neurological | Peripheral neuropathy signs | Chronic hyperglycaemia can cause sensory loss. |
Differential diagnosis
| Condition | Points toward it | Distinguishing feature |
|---|---|---|
| Primary (essential) obesity | Gradual weight gain, family history, central fat | Absence of endocrine abnormalities, normal thyroid, cortisol, sex hormones. |
| Cushing’s syndrome | Rapid central weight gain, moon face, striae, hypertension | Elevated midnight cortisol, loss of diurnal variation, positive dexamethasone suppression test. |
| Hypothyroidism | Weight gain, cold intolerance, dry skin, bradycardia | Elevated TSH, low free T4. |
| Polycystic ovary syndrome | Central obesity, hirsutism, oligomenorrhoea, infertility (women) | Elevated LH/FSH ratio, polycystic ovaries on ultrasound, hyperandrogenism. |
| HIV‑associated lipodystrophy | History of ART, peripheral lipoatrophy with central fat gain | History of protease inhibitor use, normal cortisol, HIV viral load suppressed. |
| Medication‑induced weight gain | Recent start of steroids, antipsychotics, insulin | Temporal relationship to drug initiation, dose‑response pattern. |
| Congenital lipodystrophy | Early‑onset severe insulin resistance, loss of subcutaneous fat | Genetic testing, lack of subcutaneous fat despite high BMI. |
Investigations
| Test | What it answers | Interpretation |
|---|---|---|
| Fasting plasma glucose | Baseline glucose control | ≥5.6 mmol/L = impaired fasting glucose; ≥7.0 mmol/L = diabetes. |
| 2‑hour oral glucose tolerance test | Post‑prandial glucose handling | ≥7.8 mmol/L = impaired glucose tolerance; ≥11.1 mmol/L = diabetes. |
| HbA1c | Average glycaemia over 3 months | 5.7‑6.4 % = pre‑diabetes; ≥6.5 % = diabetes. |
| Lipid profile (total, LDL, HDL, triglycerides) | Dyslipidaemia component | Triglycerides ≥1.7 mmol/L or HDL <1.0 mmol/L (men) / <1.3 mmol/L (women) meet criteria. |
| Blood pressure (average of ≥2 readings) | Hypertension component | ≥130/85 mmHg qualifies for metabolic syndrome. |
| Serum insulin (fasting) & HOMA‑IR (if available) | Degree of insulin resistance | Elevated insulin with normal glucose suggests early resistance. |
| Liver function tests (ALT, AST, GGT) | NAFLD screening | Mildly raised transaminases suggest fatty liver. |
| Ultrasound abdomen | Hepatic steatosis, gallstones | Bright liver echogenicity confirms NAFLD. |
| Thyroid function (TSH, free T4) | Exclude hypothyroidism | Elevated TSH with low free T4 indicates primary hypothyroidism. |
| Cortisol (midnight salivary or 24‑h urinary) | Exclude Cushing’s | Elevated values point to hypercortisolism. |
| HIV viral load & CD4 (if known HIV) | Assess ART‑related lipodystrophy | Suppressed viral load with low CD4 may still have ART side‑effects. |
| Renal function (creatinine, eGFR, urine albumin) | Baseline renal status | Albuminuria indicates early diabetic nephropathy. |
Diagnosis and severity
Metabolic syndrome is diagnosed when any three of the following are present (adapted to Kenyan cut‑offs):
- Waist circumference >94 cm (men) or >80 cm (women).
- Triglycerides ≥1.7 mmol/L or on lipid‑lowering therapy.
- HDL‑cholesterol <1.0 mmol/L (men) or <1.3 mmol/L (women) or on therapy.
- Blood pressure ≥130/85 mmHg or antihypertensive use.
- Fasting glucose ≥5.6 mmol/L or diagnosed diabetes.
Obesity severity (BMI classification):
| BMI (kg/m²) | Category | Clinical implication |
|---|---|---|
| 25‑29.9 | Overweight | Early metabolic changes, counsel on lifestyle. |
| 30‑34.9 | Class I obesity | Higher risk of hypertension, dyslipidaemia. |
| 35‑39.9 | Class II obesity | Consider pharmacologic adjuncts, monitor end‑organ damage. |
| ≥40 | Class III (severe) | Strong indication for multidisciplinary management, possible bariatric referral. |
Staging of NAFLD (if present) can be approximated by liver enzymes and ultrasound; referral for elastography or biopsy if suspicion of steato‑hepatitis or fibrosis.
Overall severity assessment combines:
- Number of metabolic syndrome components (≥4 = high‑risk).
- BMI class.
- Presence of target‑organ damage (hypertension, dyslipidaemia, impaired glucose, NAFLD, albuminuria).
Patients with ≥3 components, BMI ≥35 kg/m², or any end‑organ involvement are classified as high‑risk and merit aggressive lifestyle intervention, early pharmacotherapy (e.g., metformin for insulin resistance, statin for dyslipidaemia, ACE‑inhibitor/ARB for hypertension), and close follow‑up every 3‑6 months. Those with 3 components, BMI 25‑34.9 kg/m², and no organ damage are moderate‑risk; lifestyle measures are first line with periodic monitoring.
Management
Immediate stabilisation
- Airway‑breathing‑circulation – obese patients may have obstructive sleep‑apnoea (OSA) or hypoventilation; ensure supine positioning with head‑of‑bed elevation, give supplemental O₂ if SpO₂ < 94 % and consider non‑invasive ventilation for acute hypercapnic respiratory failure.
- Fluid balance – correct dehydration or electrolyte disturbance before any caloric restriction; give isotonic fluids judiciously in patients with heart failure.
- Glycaemic emergency – treat severe hyperglycaemia or ketoacidosis according to standard protocols (insulin infusion, fluid replacement, potassium monitoring).
Definitive treatment
| Goal | Intervention | Rationale |
|---|---|---|
| Weight loss (5–10 % in 6 months) | Lifestyle modification: calorie‑restricted diet (≈500 kcal deficit), high‑protein, low‑glycaemic index, ≥150 min/week moderate activity (walking, cycling) | Reduces insulin resistance, improves lipid profile, lowers BP |
| Behavioural support | Structured counselling, motivational interviewing, group sessions, digital apps | Improves adherence, addresses emotional eating |
| Pharmacotherapy (if BMI ≥ 30 kg/m² or ≥ 27 kg/m² with comorbidity) | • GLP‑1 receptor agonist (e.g., liraglutide) <br>• SGLT‑2 inhibitor (e.g., empagliflozin) <br>• Orlistat (lipase inhibitor) | GLP‑1 agents lower appetite and improve glycaemia; SGLT‑2 reduce weight and cardiovascular risk; Orlistat blocks fat absorption – useful when cost is limiting |
| Bariatric surgery (BMI ≥ 35 kg/m² with metabolic disease, or BMI ≥ 40 kg/m²) | Sleeve gastrectomy or Roux‑en‑Y gastric bypass – performed in a centre with multidisciplinary team | Provides >25 % excess weight loss, rapid remission of type 2 diabetes, improves hypertension and dyslipidaemia |
| Management of comorbidities | • Antihypertensives (ACE‑I/ARB, calcium‑channel blocker) <br>• Statins for dyslipidaemia <br>• Metformin for insulin resistance (if not contraindicated) | Target BP < 130/80 mmHg, LDL‑C < 2.5 mmol/L, improve insulin sensitivity |
| Treat OSA | CPAP therapy, weight loss, positional therapy | Reduces cardiovascular strain, improves daytime alertness |
| Address HIV/TB/other tropical infections | Optimise antiretroviral therapy, complete TB treatment, treat malaria promptly; avoid steroids that worsen weight gain unless essential | Prevents drug‑induced metabolic derangements |
Monitoring and follow‑up
- Weight & waist circumference: every 4 weeks initially, then 3‑monthly.
- Blood pressure, fasting glucose/HbA1c, lipid panel: baseline, 3 monthly for the first year, then 6‑monthly.
- Liver function & renal function: before starting GLP‑1 agonists or SGLT‑2 inhibitors, then 6‑monthly.
- Nutrient deficiencies after bariatric surgery (iron, B12, vitamin D) – supplement as needed.
- Psychological status – screen for depression or eating‑disorder behaviours at each visit.
Contra‑indications & safety
- GLP‑1 agonists: contraindicated in personal/family history of medullary thyroid carcinoma or MEN‑2.
- SGLT‑2 inhibitors: avoid in recurrent genital infections, severe renal impairment, or uncontrolled dehydration.
- Orlistat: avoid in chronic malabsorption, cholestasis, or pregnancy.
- Bariatric surgery: contraindicated in uncontrolled psychiatric illness, active substance abuse, or severe cardiopulmonary disease not optimised.
Complications and prognosis
| System | Typical complication | Clinical impact |
|---|---|---|
| Cardiovascular | Ischaemic heart disease, heart failure, atrial fibrillation | Leading cause of mortality; weight loss reduces event rates |
| Metabolic | Type 2 diabetes mellitus, dyslipidaemia, non‑alcoholic fatty liver disease (NAFLD) → steatohepatitis, cirrhosis | Progression to end‑stage liver disease if untreated |
| Respiratory | Obstructive sleep‑apnoea, obesity hypoventilation syndrome | Daytime somnolence, pulmonary hypertension |
| Musculoskeletal | Osteoarthritis, gout | Reduced mobility, chronic pain |
| Gastro‑intestinal | Gastro‑oesophageal reflux, gallstones | May limit diet choices, require surgical intervention |
| Cancer | Endometrial, breast, colorectal, pancreatic | Relative risk rises with each 5 kg increase in weight |
| Psychosocial | Depression, stigma, reduced quality of life | Affects adherence to therapy |
Prognosis improves markedly with ≥ 5 % weight loss: blood pressure falls, insulin sensitivity improves, and cardiovascular risk scores decline. Early bariatric surgery in eligible patients can lead to remission of type 2 diabetes in up to 60 % of cases.
High‑yield exam points
- Look‑alike conditions: Cushing’s syndrome, hypothyroidism, polycystic ovary syndrome – differentiate by cortisol levels, thyroid function tests, and androgen profile.
- Commonest wrong first step: Jumping straight to pharmacotherapy without lifestyle assessment; examiners expect a structured diet‑exercise plan first.
- Bedside questioning: “What waist‑circumference cut‑off defines central obesity in this patient?”; “Explain why GLP‑1 agonists are preferred over older agents in a patient with type 2 diabetes and obesity.”; “List three safety checks before initiating an SGLT‑2 inhibitor.”
Clinical case
Case: 45‑year‑old male, HIV‑positive on ART for 8 years, presents with progressive abdominal girth increase, fatigue, and BP 150/95 mmHg. BMI 33 kg/m², waist 112 cm, fasting glucose 7.2 mmol/L, triglycerides 2.5 mmol/L, ALT 68 U/L. No OSA symptoms.
Questions
- What is the most appropriate next step in management?
Answer: Initiate a structured lifestyle programme (dietary calorie restriction + 150 min/week moderate activity) and optimise ART to a regimen with lower metabolic impact.
- Which pharmacologic agent would be most suitable if weight loss stalls after 3 months?
Answer: Add a GLP‑1 receptor agonist – it promotes satiety, improves glycaemia and has cardiovascular benefit, and is not contraindicated in HIV.
- What complication should be screened for given his waist measurement?
Answer: Non‑alcoholic fatty liver disease – order hepatic ultrasound and calculate fibrosis score (e.g., Fib‑4).
Practice questions
Question 1
A 52‑year‑old woman with BMI 38 kg/m² presents with daytime sleepiness and a blood pressure of 160/92 mmHg. Her overnight oximetry shows an AHI of 28. What is the most appropriate immediate intervention?
A. Start a high‑protein diet
B. Initiate CPAP therapy
C. Prescribe a thiazide diuretic
D. Refer for bariatric surgery
Answer: B. Initiate CPAP therapy – severe OSA must be treated first to improve oxygenation and reduce cardiovascular strain.
Question 2
A 30‑year‑old man with newly diagnosed metabolic syndrome has fasting glucose 6.8 mmol/L, triglycerides 2.2 mmol/L, HDL‑C 0.9 mmol/L, BP 138/85 mmHg, BMI 31 kg/m². Which of the following is the best first‑line pharmacologic choice?
A. Metformin
B. Statin
C. GLP‑1 receptor agonist
D. Orlistat
Answer: A. Metformin – first‑line for insulin resistance in metabolic syndrome when lifestyle alone is insufficient; statin is indicated for dyslipidaemia but weight‑loss‑focused therapy is metformin.
Question 3
A patient on an SGLT‑2 inhibitor presents with a painful genital eruption and dysuria. Which action is correct?
A. Continue drug, add topical antifungal
B. Stop the SGLT‑2 inhibitor immediately
C. Switch to a GLP‑1 agonist and treat infection
D. Increase fluid intake only
Answer: B. Stop the SGLT‑2 inhibitor immediately – genital infections are a contraindication to continuation until resolved.
Question 4
Which laboratory result most strongly suggests non‑alcoholic steatohepatitis (NASH) rather than simple steatosis in an obese patient?
A. ALT > 2 × ULN
B. Elevated fasting glucose
C. Triglycerides > 1.7 mmol/L
D. Low HDL‑C
Answer: A. ALT > 2 × ULN – marked transaminase elevation points toward inflammatory NASH.
Question 5
A 60‑year‑old woman with BMI 42 kg/m² and uncontrolled hypertension is being considered for bariatric surgery. Which of the following is an absolute contraindication?
A. Controlled type 2 diabetes
B. Severe obstructive sleep apnoea on CPAP
C. Active untreated depression
D. Prior cholecystectomy
Answer: C. Active untreated depression – psychiatric instability must be addressed before elective bariatric surgery.
Drafted with AI assistance from standard references and reviewed for structure. Check details against your lecture notes and the Kenya MoH guideline.