20th February 2024

Obesity

Obesity and its impact

Epidemiology

The incidence of obesity is rising worldwide, with up to 1 in 4 adults in the UK classified as obese. This appears to be worse in the lower socioeconomic populations and those of African, Caribbean and Pakistani descent. Modifiable obesity-related factors include food consumption, physical activity and psychological factors. Other non-modifiable factors include genetics, associated medical conditions and medication use. 

The body mass index (BMI) identifies and quantifies obesity. The cut-off utilised by NICE is as follows:

• Healthy – 18.5-24.9kg/m²
• Overweight – 25-29.9 kg/m²
• Obesity I – 30 – 34.9 kg/m²
• Obesity II – 35-39.9 kg/m²
• Obesity III – ≥ 40 kg/m²

In addition, waist circumference is also utilised in patients with BMI<35kg/m² to identify obesity-related problems. A waist circumference of ≥ 94cm in males and ≥ 80cm in females indicates an increased risk for obesity-related problems. 

Obesity is caused by a mismatch between energy intake and expenditure, with its direct pathophysiology not wholly known. Hormones like leptin and ghrelin have been shown to affect the central nervous system regarding appetite. 

Impact on health

Obesity is one of the leading causes of death worldwide. It is associated with an increased risk of chronic conditions, including ischaemic heart disease, type 2 diabetes mellitus, metabolic syndrome, oesophageal reflux, cancer, obstructive sleep apnoea and osteoarthritis. 

It also results in a direct reduction in life expectancy with increased costs associated with healthcare visits.

References

• Frantzides, C. T., & Luu, M. B. (2020 Jan 28). Obesity in Adults. Accessed on 2022 Mar 26. Available from: https://bestpractice.bmj.com/topics/en-gb/211. 
• National Institute for Health and Care Excellence. (2014). Obesity: identification, assessment and management. Accessed on 2022 Mar 26. Available from: https://www.nice.org.uk/guidance/cg189/resources/obesity-identification-assessment-and-management-pdf-35109821097925. 
• National Institute for Health and Care Excellence Clinical Knowledge Summary. (2017). Obesity. Accessed on 2022 Mar 26. Available from: https://cks.nice.org.uk/topics/obesity/. 
• Perreault, L., & Apovian, C. (2021 Jul 12). Obesity in adults: Overview of management. Accessed on 2022 Mar 26. Available from: https://www.uptodate.com/contents/obesity-in-adults-overview-of-management?search=obesity&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1. 

Treatment options

Lifestyle advice 

The subject of weight may be sensitive for some patients and should be approached with sensitivity. Clinicians should work with the patient to assess their readiness to change and provide advice where appropriate. Clinicians can carry out brief interventions to assess their willingness/motivation to lose weight, along with counselling on the harm associated with obesity. 

The treatment method should be multi-modal, with patients receiving advice regarding dietary intake and increasing physical activity. Patients should be advised to maintain a caloric deficit while engaging with moderate exercise for at least 30 minutes per session, five days a week. Behavioural interventions can be carried out to help patients monitor their progress, address potential issues around relapses, and set realistic goals for their target. 

Other centres, such as lifestyle weight management services, can be considered for patients in the overweight category with an at-risk ethnicity or whose weight circumference suggests they are at risk of obesity-related complications. Specialist obesity services can be considered if the patient requires further interventions. 

Medical therapies

Medical therapies for weight loss should only be considered in conjunction with the lifestyle advice highlighted above. Treatments that have been licensed for weight loss include Orlistat and liraglutide. It is important to highlight to patients that this is often not a long-term solution, and side effects of the medications may result in reduced adherence. 

Orlistat is licensed in patients with a mild hypocaloric diet with a BMI of ≥30 kg/m2 or a BMI ≥ 28 kg/m2 associated with co-morbidities. Orlistat functions by inhibiting gastric and pancreatic lipase, increasing faecal fat excretion. Studies have shown this results in modest weight loss. The most common side effect is diarrhoea, faecal incontinence, flatus with discharge, abdominal cramping and oily spotting. This is contraindicated in patients with chronic malabsorption syndrome and should be used with caution in patients with CKD.  

Liraglutide has also been licensed with a caloric-reduced diet and increased physical activity. It can be used in patients with a BMI of ≥35 kg/m2 with associated T2DM or cardiovascular risk factors. Liraglutide is a GLP-1 agonist and mimics the function of GLP-1. It is associated with reduced glucagon secretion and delayed gastric emptying. It is associated with nausea, vomiting and diarrhoea. It is rarely associated with pancreatitis and renal impairment. If the patient has type-2 diabetes, this may be an ideal treatment option because it improves glycemic control and reduces weight loss. 

Surgical therapies

Bariatric surgery is usually considered in patients who have fulfilled all the following criteria. 

• BMI of ≥40 kg/m2 or BMI between 35-40 kg/m2 with significant co-morbidities ( hypertension, type 2 diabetes, mobility problems, sleep apnoea, GORD) that will improve with weight loss.
• All appropriate non-surgical methods have been attempted without beneficial weight loss.
• Willing to receive intensive management at a specialist obesity centre.
• Fit for anaesthesia and surgery.
• Committed towards long-term follow-up.
• Exceptions towards the criteria above include:
• Patients with a BMI ≥50kg/m2 where other interventions have not been successful.
• Patients with a recent diagnosis of type 2 diabetes
• A BMI between 30 and 34.9 kg/m2 can be considered for assessment for bariatric surgery if they are willing to receive input from a specialist obesity centre.
• BMI ≥35kg/m2 can be offered an expedited assessment for bariatric surgery if they are willing to receive input from a specialist obesity centre.

Common bariatric procedures include sleeve gastrectomy, Roux-en-Y bypass, gastric banding and intragastric balloon. Candidates are only expected to know the indication for consideration of bariatric surgery rather than for each procedure. 

References

• Frantzides, C. T., & Luu, M. B. (2020 Jan 28). Obesity in Adults. Accessed on 2022 Mar 26. Available from: https://bestpractice.bmj.com/topics/en-gb/211. 
• National Institute for Health and Care Excellence. (2014). Obesity: identification, assessment and management. Accessed on 2022 Mar 26. Available from: https://www.nice.org.uk/guidance/cg189/resources/obesity-identification-assessment-and-management-pdf-35109821097925. 
• National Institute for Health and Care Excellence Clinical Knowledge Summary. (2017). Obesity. Accessed on 2022 Mar 26. Available from: https://cks.nice.org.uk/topics/obesity/. 
• Perreault, L., & Apovian, C. (2021 Jul 12). Obesity in adults: Overview of management. Accessed on 2022 Mar 26. Available from: https://www.uptodate.com/contents/obesity-in-adults-overview-of-management?search=obesity&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1. 
• National Institute for Health and Care Excellence. (2020). Liraglutide for managing overweight and obesity. Accessed on 2022 Apr 1. Available from: https://www.nice.org.uk/guidance/TA664/chapter/1-Recommendations.