Medications are NOT generally recommended for those <12 y/o
- Only consider in exceptional circumstances, if severe comorbidities are present
Overweight and Obesity
NICE guideline [NG246] Overweight and Obesity Management. Published: Jan 2025.
Background Information
Aetiology
Overweight and obesity are caused by a chronic imbalance between energy intake and energy expenditure, resulting in excess body fat accumulation.
Aetiology is multi-factorial: [Ref1][Ref2]
- Genetic predisposition (usually polygenic and interacts with environmental factors)
- Environmental contributors
- Excessive caloric intake
- Consumption of ultra-processed foods and sugar-sweetened beverages
- Low physical activity
- Low socioeconomic status
- Chronic stress
- Insufficient sleep
Medical causes of overweight and obesity: [Ref1][Ref2]
- Depression
- Hypothyroidism
- Cushing’s syndrome
- Binge eating disorder
Medications associated with weight gain: [Ref1][Ref2]
- Certain diabetes medications (insulin, sulfonylurea, pioglitazone) (other medications are either weight-neutral or promote weight loss)
- Antipsychotics (esp. olanzapine)
- Systemic corticosteroids
- Antidepressants (e.g. amitriptyline, mirtazapine)
- Antiepileptics (e.g. gabapentin, carbamazepine)
- Beta blockers
- Protease inhibitors
Complications
Weight-related comorbidities include: [Ref1][Ref2]
- Metabolic syndrome (including hypertension, diabetes, dyslipidaemia)
- OSA
- Osteoarthritis
- Hepatic steatosis, NAFLD
- GORD
Identification and Assessment
Methods of Measurement
NICE recommends BMI as a practical measure of overweight and obesity.
- BMI: weight (kg) / (height in m)2
NICE also recommends measuring waist-to-height ratio in those with BMI <35 kg/m2
- Waist-to-height ratio is a practical estimate of central adiposity, which can be used to assess and predict health risks
Interpretation (Adults)
BMI
| Classification | BMI range (kg/m2) |
|---|---|
| Healthy weight | 18.5 – 24.9 |
| Overweight | 25.0 – 29.9 |
| Obesity class 1 | 30.0 – 34.9 |
| Obesity class 2 | 35.0 – 39.9 |
| Obesity class 3 | ≥40.0 |
NICE recommends lower BMI thresholds in people with South Asian, Chinese, other Asian, Middle Eastern, Black African, and African-Caribbean backgrounds as they are prone to central adiposity and their cardiometabolic risk occurs at lower BMI:
- Overweight: BMI 23 – 27.4 kg/m2
- Obesity: BMI ≥27.5 kg/m2
- Obesity class 2 and 3: minus 2.5 kg/m2 from the above thresholds
Note that BMI is NOT a direct measure of central adiposity.
BMI should be interpreted with caution in:
- Adults with high muscle mass
- ≥65 y/o
Central Adiposity (Waist-to-Height Ratio)
Central adiposity should be classified based on waist-to-height ratio
The following waist-to-height classification can be used for people with BMI <35 kg/m2 of both sexes and all ethnicities, including adults with high muscle mass.
| Classification | Waist-to-height ratio range |
|---|---|
| Healthy | 0.4 – 0.49 |
| Increased | 0.5 – 0.59 |
| High | ≥0.6 |
Interpretation (Children and Young People)
BMI
Centiles and standard deviations should be used to classify BMI.
| Classification | BMI (centile and SD) |
|---|---|
| Overweight | BMI 91st centile + 1.34 SD |
| Clinical obesity | BMI 98th centile + 2.05 SD |
| Severe obesity | BMI 99.6th centile + 2.68 SD |
Central Adiposity (Waist-to-Height Ratio)
Central adiposity should be classified based on waist-to-height ratio
The classification is the same as adults:
| Classification | Waist-to-height ratio range |
|---|---|
| Healthy | 0.4 – 0.49 |
| Increased | 0.5 – 0.59 |
| High | ≥0.6 |
Management
Conservative / General Management
Key point is employing a multicomponent management strategy with long-term support, including:
- Increase physical activity changes, and
- Reduced-calorie diet
Pharmacological Management
All medicines for weight management should be used alongside a reduced-calorie diet and increased physical activity.
| Drug | Class | Indications | Important side effects | Pregnancy and contraception |
|---|---|---|---|---|
| Orlistat | Lipase inhibitor |
|
|
Do not use |
| Tirzepatide | GLP-1 and GIP agonist |
|
|
|
| Semaglutide | GLP-1 agonist |
|
||
| Liraglutide |
|
For tirzepatide, semaglutide and liraglutide, NICE recommends using lower BMI thresholds (usually reduced by 2.5 kg/m2) for people from South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean ethnic backgrounds.
Children and Young People
Surgical Management
Referral Criteria
Refer to specialist overweight and obesity management service to assess for bariatric surgery eligibility if:
- BMI ≥40 kg/m2 or BMI 35-39.9 kg/m2 + significant health conditions that can be improved if they lose weight, and
- Patient agrees to necessary long-term follow-up after surgery
Early assessment for bariatric surgery should be considered in:
- BMI 30-34.9 kg/m2, and
- Recent-onset type 2 diabetes (diagnosed <10 years), and
- Receiving, or will receive, assessment in a specialist overweight and obesity management service
Consider referral for people of South Asian, Chinese, other Asian, Middle Eastern, Black African or African–Caribbean background using a lower BMI threshold (reduced by 2.5 kg/m2)
Surgical Options
NICE did not make any specific recommendations on which surgical interventions to use, but it is important to know about the commonly used bariatric surgeries.
| Procedure | Type | Mechanism | Disadvantages |
|---|---|---|---|
| Sleeve gastrectomy | Restrictive | Removes ~80% of the stomach (greater curvature) |
|
| Adjustable gastric banding | Inflatable band around the upper stomach, adjustable via subcutaneous port |
|
|
| Roux-en-Y gastric bypass | Restrictive + malabsorptive | A small stomach pouch is created and connected to the intestine to bypass the duodenum and proximal jejunum |
|
| Biliopancreatic diversion with duodenal switch | Sleeve gastrectomy + bypass of most of the small intestine |
|