Obesity is a chronic, relapsing, multifactorial disease characterized by excessive accumulation of body fat that adversely affects health. It is associated with increased morbidity and mortality through its effects on the cardiovascular, endocrine, respiratory, musculoskeletal, and gastrointestinal systems. Obesity significantly increases the risk of type 2 diabetes mellitus, hypertension, dyslipidaemia, coronary artery disease, stroke, osteoarthritis, obstructive sleep apnoea, several cancers, and reduced quality of life.

Individuals living with obesity frequently experience social stigma, discrimination, depression, anxiety, and reduced self-esteem. Effective management requires long-term lifestyle modification, behavioural support, and when appropriate, pharmacological therapy or bariatric surgery.

Risk factors

• Excess caloric intake

• Physical inactivity

• Sedentary lifestyle

• Family history of obesity

• Genetic predisposition

• Increasing age

• Obesogenic medications (e.g., corticosteroids, some antidepressants and antipsychotics)

• Endocrine disorders (e.g., hypothyroidism, Cushing syndrome)

• Poor sleep

• Psychological disorders

• Excess alcohol consumption

• Socioeconomic and environmental factors

Pathophysiology

Obesity develops when energy intake consistently exceeds energy expenditure, resulting in excessive storage of triglycerides within adipose tissue. Progressive adipocyte enlargement and hyperplasia lead to chronic low-grade inflammation, insulin resistance, altered adipokine secretion, endothelial dysfunction, and metabolic abnormalities that increase the risk of cardiovascular disease, diabetes mellitus, fatty liver disease, and other obesity-related complications.

Clinical presentation

Many patients are asymptomatic initially and obesity is identified during routine assessment. Clinical features may include:

• Progressive weight gain

• Increased waist circumference

• Reduced exercise tolerance

• Shortness of breath on exertion

• Excessive daytime sleepiness

• Snoring or symptoms of obstructive sleep apnoea

• Joint pain, particularly involving the knees and hips

• Chronic back pain

• Psychological distress, depression, anxiety, or reduced self-esteem

Diagnostic criteria

Obesity is diagnosed using body mass index (BMI):

Adults attending health facilities should have their:

• Height measured

• Weight measured

• Waist circumference measured

at least once every year.

Patients should also be evaluated for obesity-related comorbidities including:

• Hypertension

• Type 2 diabetes or prediabetes

• Dyslipidaemia

• Elevated waist circumference

• Non-alcoholic fatty liver disease

• Cardiovascular disease

Investigations

Initial assessment should include:

• Body mass index (BMI)

• Waist circumference

• Blood pressure

• Fasting blood glucose or HbA1c

• Lipid profile

• Liver function tests (especially elevated liver enzymes suggesting fatty liver disease)

• Assessment of diet and physical activity

• Assessment of sleep disorders

• Assessment of eating behaviours and mood disorders

• Review of medications that may contribute to weight gain

• Cardiovascular risk assessment

Management

Management aims to achieve sustained weight loss, improve metabolic health, reduce obesity-related complications, and improve quality of life.

Non-pharmacological treatment

Lifestyle modification remains the cornerstone of obesity management.

Weight loss targets

• Aim to lose 5–10% of baseline body weight within 6 months.

• A weight loss of approximately 0.5 kg per week is recommended.

• Even a sustained weight loss of 3–5% significantly reduces triglycerides, blood glucose, HbA1c, and the risk of developing type 2 diabetes.

• Greater weight loss further improves blood pressure, LDL cholesterol, HDL cholesterol, and reduces the need for antihypertensive, antidiabetic, and lipid-lowering medications.

Dietary management

Create an energy deficit through calorie restriction.

Recommended daily caloric intake:

• Women: 1,200–1,500 kcal/day

• Men: 1,500–1,800 kcal/day

• Approximately 25–30 kcal/kg/day

Dietary recommendations include:

• Approximately 20% of total energy from high-quality proteins such as lean meat and legumes.

• Approximately 20% or less of total energy from fats.

• Avoid saturated fats.

• Restrict fried foods.

• Choose low-fat dairy products.

• Approximately 60% of total energy from complex carbohydrates.

• Increase intake of whole grains, roots, tubers, vegetables, and fruits.

• Limit sugars, honey, and refined carbohydrates.

• Avoid alcohol because it provides excess calories with little nutritional value.

• Avoid fad diets and unsustainable weight-loss practices.

• Very-low-calorie diets (<800 kcal/day) should only be undertaken under medical supervision.

Physical activity

• Begin with at least 30 minutes of moderate-intensity exercise 3–5 times per week.

• Progress to at least 60 minutes on most days of the week.

• Include muscle-strengthening activities on at least two days per week.

• Encourage increased daily physical activity such as walking and stair climbing.

Behavioural interventions

• Identify behaviours contributing to overeating and physical inactivity.

• Set realistic, measurable lifestyle goals.

• Maintain food, exercise, and weight records.

• Eat breakfast regularly.

• Maintain consistent eating patterns.

• Encourage family involvement and social support.

• Participate in structured lifestyle programmes for at least six months.

• After successful weight loss, continue regular follow-up with maintenance programmes, monthly or more frequently, while maintaining 200–300 minutes of physical activity per week.

Referral

Refer patients to a specialist metabolic obesity clinic or bariatric surgery service when:

• Weight loss of at least 5% has not been achieved after 3 months of comprehensive lifestyle intervention with or without pharmacotherapy.

• BMI ≥40 kg/m².

• BMI ≥35 kg/m² with obesity-related comorbidities despite optimal behavioural treatment.

Monitor medication requirements during weight loss, particularly antihypertensive and antidiabetic medicines, to prevent hypotension and hypoglycaemia.

Pharmacological treatment

Drug therapy may be considered in patients with:

• BMI ≥30 kg/m².

• BMI ≥27 kg/m² with obesity-related comorbidities.

• Failure to lose approximately 0.5 kg per week after 3–6 months of lifestyle intervention.

Recommended medication:

• Orlistat: 120 mg orally every 8 hours with each main meal containing fat (during the meal or within one hour after eating).

Treatment should be continued beyond 12 weeks only if at least 5% of the initial body weight has been lost since starting therapy and should always be used as an adjunct to lifestyle modification.

Innovative obesity care strategies

Primary care services should incorporate:

• Electronic health records and patient registries.

• Multidisciplinary care teams.

• Evidence-based clinical decision support.

• Text messaging and mobile health applications.

• Remote monitoring of weight, blood pressure, and blood glucose.

• Telephone and internet-based lifestyle support programmes.

Healthcare facilities should promote healthy environments by:

• Providing healthy food choices.

• Encouraging healthy beverage options.

• Restricting fast-food outlets within hospital premises.

• Supporting healthcare workers as role models for healthy lifestyles.

Complications

• Type 2 diabetes mellitus

• Hypertension

• Dyslipidaemia

• Coronary artery disease

• Stroke

• Heart failure

• Pulmonary embolism

• Obstructive sleep apnoea

• Non-alcoholic fatty liver disease

• Osteoarthritis

• Chronic back pain

• Gallbladder disease

• Colorectal cancer

• Reduced quality of life

• Depression and anxiety

• Premature mortality

Prognosis

Obesity is a chronic disease that requires lifelong management. Sustained lifestyle modification combined with behavioural support can achieve clinically meaningful weight loss and significantly reduce cardiovascular and metabolic risk. Pharmacotherapy and bariatric surgery may provide additional benefit in selected patients. Long-term success depends on continued adherence to healthy eating, regular physical activity, and ongoing clinical follow-up.

Prevention

• Maintain a healthy balanced diet.

• Engage in regular physical activity.

• Avoid excessive caloric intake.

• Limit consumption of sugar-sweetened beverages and processed foods.

• Maintain a healthy body weight.

• Screen adults annually using BMI and waist circumference.

• Identify and manage obesity-related risk factors early.

• Promote healthy lifestyles at individual, family, community, and healthcare facility levels.