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Physician’s guide to weight loss therapy

Obesity is globally recognised as a complex, relapsing, and chronic disease.1 Given its multifactorial nature, treating obesity requires an evidence-based management approach. Effective weight loss therapy aims to treat and prevent physical complications, whilst supporting patients’ mental well-being and tackling weight stigma.

This guide aims to help healthcare professionals explore the efficacy and key limitations of the three main modalities of obesity treatment. By learning about these treatments for obesity, medical professionals may treat obesity with a comprehensive, holistic management approach.

Goals of weight loss therapy for obesity

The principal goals in obesity management are to: 

  1. Prevent complications by trying to keep the patient metabolically healthy (if possible)2
  2. Treat complications if they are already present2
  3. Reduce stigmatisation2
  4. Restore well-being, positive body image and self-esteem2

There are multiple guidelines available for obesity management, which include recommendations on the three categories of intervention: lifestyle therapy, pharmacotherapy and bariatric surgery. Each category can offer different levels of weight loss.3

Health benefits of weight loss therapy

Successful weight loss therapy has a number of health benefits:

● Prevention of obesity complications (e.g. cardiovascular diseases, high blood pressure, and type 2 diabetes)4: Weight loss can prevent a range of obesity-related complications. There is a linear correlation between weight loss and improvements in cardiovascular risk factors including blood pressure, triglycerides and HDL cholesterol.2  Through a successful and maintained weight loss of between 5-15% diabetes remission can occur in those who were recently diagnosed.2 Read more about the benefits of weight loss on health.

● Reduction of obesity-related health risks: Some of the complications experienced by patients with obesity can be due to excessive weight, including osteoarthritis, obstructive sleep apnoea, and asthma among others.Weight loss decreases the pressure on joints in those with osteoarthritis and the pressure on the airways in both asthma and obstructive sleep apnoea.

● Improvement in quality of life: A range of measures are used to assess quality of life in those with obesity including the DALY (disability-adjusted life years) measurement, which looks at the number of years of good health lost by a particular condition.4 In particular, maintaining weight loss been shown to cause marked improvement in quality of life measures.5

Scope of application

  • Cornerstone treatment of obesity: Lifestyle therapy modifications are the cornerstone of all weight loss therapy and should be the first-line intervention for all individuals. Importantly, lifestyle modifications must be included as part of any weight loss intervention.2  

  • Body Mass Index (BMI) kg/m2: Lifestyle therapy modifications for weight loss are recommended for all individuals with a BMI ≥25 kg/m2.


In various studies, lifestyle modifications, including low-calorie diets, have shown to reduce weight by between 3-8%.6,7

Types of lifestyle therapy modifications

Lifestyle changes encompass three main categories:

  • Diet modification: Typically involving calorie reduction diets. Many diets exist, including low carbohydrate, low glycaemic index, low fat or Mediterranean diets.5
  • Increased physical activity: Implementation of regular aerobic exercise and/or strength training.5 
  • Behavioural change: Targeting habit change, self-monitoring, and goal-setting. This may include cognitive-behavioural therapy for obesity to facilitate change in thinking patterns.5

Mode of action

Diet modification is based on calorie reduction from dietary sources and causes patients to lose body weight through a calorie deficit.5 As the body uses fat stores in the liver and fatty tissues as fuel, rather than food, this causes a reduction in weight.

Increased exercise also contributes to calorie deficit as calories are used for physical movement.Regular bouts of aerobic exercise can also reduce blood pressure and hyperlipidaemia which are obesity-related risks.However, physical activity alone has been shown to have limited benefit in weight loss without calorie restriction.Therefore, a combination approach is best.

Behavioural change therapy works by setting realistic goals and self-monitoring. Counter-intuitively, this is a holistic approach which recognises that multiple factors outside of behaviour contribute to obesity, such as genetics and hormonal influences. That’s why behavioural therapy aims to set specific goals within a range that an individual can realistically reach.Regular self-monitoring has consistently been linked to both short and long-term weight loss and this is incorporated into behavioural therapy.5  Crucially, through cognitive restructuring, psychological triggers can be modified so that patients can overcome unhealthy eating habits.5

Key limitations

  • Lack of patient compliance: Weight loss through lifestyle modifications tends to be challenging for patients. A combination of psychological, physiological, and socioeconomic factors contribute to difficulty of sustained habit changes. Healthcare professionals may also find lifestyle modification difficult to initiate, with time constraints often cited as a key barrier.1
  • Rebound weight gain: Lifestyle interventions are not always sufficient to maintain weight loss.8, 9 In fact, studies show that in the long-term, weight loss is not sustained and there is instead weight gain compared to the initial weight.  Mann et al. (2007) completed a review of randomised control trials of patients on calorie-restricting diets. The results showed that, in the long term, between one to two-thirds of those on such a diet regained more weight than they originally lost on their diets.8

To learn more about diet difficulties, visit ‘Why don’t diets work?’. 

Further guidance

For more guidance on Lifestyle Therapy Modifications, see page 91 of the AACE/ACE Guidelines (2016).


Scope of application

  • BMI kg/m2: Pharmacotherapy can be considered in patients with a BMI of ≥30 kg/m2, or ≥27 kg/m2 with obesity-related complications if lifestyle therapy does not provide sufficient clinical benefit for patients.3 
  • Comprehensive disease management: Pharmacological treatment should be considered as part of a comprehensive strategy for disease management.4 
  • Post-bariatric surgery: There is also a role for pharmacotherapy post-bariatric surgery. 10-20% of all patients will regain all the weight they lost following bariatric surgery.10 In these cases, pharmacotherapy is recommended for patients with a partial weight loss response or who have experienced weight regain after bariatric surgery.11


Pharmacological treatments of obesity utilise different mode of actions and across the different classes, they can provide 3-9% weight loss.12

Benefits of pharmacotherapy include:

  • Maintenance of compliance to lifestyle changes: Pharmacological management may be a useful adjunct to help patients maintain lifestyle changes that lead to a healthier weight.4
  • Reduction of obesity-related health risks: Since pharmacological adjuncts can lead to potentially increased weight loss, this further decreases the risk of weight-related health problems such as osteoarthritis and sleep apnoea.2 
  • Improvement in quality of life: Pharmacotherapy has been shown to reduce the number of disability-adjusted life years, thus improving quality of life.This may be linked to increased maintenance of weight loss which has also been shown to cause marked improvement in quality of life measures.4

Types of pharmacological obesity treatments

Pharmacotherapy can be divided into non-prescription and prescription medications. Both are potential medical treatments for obesity but vary in efficacy.

Over-the-counter diet supplements for weight loss

Some diet supplements available without prescription claim to help with medical weight loss; however, there is little evidential basis to verify their use as weight loss treatments. In many countries, herbal products are classified under dietary supplements and therefore are not subject to regulatory testing and review, and therefore could be risky to health.

Prescription weight loss medications

Prescription weight loss medications are only available following prescription by a qualified health professional.

Different prescribed weight loss medications contain different types of medication and can have differing effects. Studies have shown that taking prescription weight loss medications can result in between 3-9% weight loss.12 Other studies have shown that some individuals (6-20%) taking prescription weight loss medications in conjunction with lifestyle changes both lose 10% or more of their initial weight and maintain that initial weight loss.13 This highlights the role of pharmacotherapy in augmenting weight loss or preventing regain after initial weight loss through lifestyle interventions.13

Mode of action

Anti-obesity medications can act directly on the central nervous system, inducing weight loss by reducing appetite, or act peripherally and induce weight loss by interfering with fat absorption from the gastrointestinal tract.14

Key limitations

Medications cannot replace key lifestyle factors such as regular physical activity or healthy eating habits. Prescription medications in conjunction to a lifestyle program have shown clinically meaningful weight loss results, thus a combination approach is recommended.13 It is also important to consider the side effects of prescription medications and a risk-benefit analysis should be performed prior to prescription. Delivering the best treatment for obesity should always be holistic and consider the patient’s needs.

Further guidance

For more guidance on Pharmacological Treatment Options, see page 102 of the AACE/ACE Guidelines (2016). 


Scope of application

  • Management of severe excess weight: Bariatric surgery is the third-line and currently most efficient intervention for obesity management. It is intended to manage excess weight that is severe and/or associated with severe weight-related complications.3,15 Its efficacy for severe excess weight makes it a suitable morbid obesity treatment. 
  • BMI kg/m2: Bariatric surgery is used in patients with a BMI ≥40 kg/m2, more than 45kg overweight or with a BMI ≥35 kg/m2 and at least one or more obesity-related complication.3,15


There are a number of different types of weight loss surgery, with each option providing different weight loss efficacies ranging between 7-38%.16,17 This efficacy means that bariatric surgery can be a highly effective method of weight loss for patients who are overweight or living with obesity.

One study showed that rebound weight gain can occur in up to 50% of people, two years following surgery.18 The percentage of weight regain varied amongst individuals and depending on the type of bariatric surgery, studies have shown a mean weight regain of between 8-23.4% of the initial weight loss.18, 19 Although there can be rebound weight gain, overall weight loss through bariatric surgery remains high compared to non-surgical weight loss treatments.3,15 This makes bariatric surgery an effective treatment for weight loss.

Types of bariatric surgery and modes of action

The most common types of weight loss surgery are:

  • Gastric band: A band is placed around the stomach and this limits stomach distension. As a result, patients feel fuller much sooner.20 
  • Roux-en-Y gastric bypass: The top of the stomach is attached to the start of the small intestine. This causes the stomach to fill more quickly, allowing patients to feel fuller, sooner.20 
  • Sleeve gastrectomy: A part of the stomach is removed surgically so that the patient can feel full with decreased food intake.20

Key limitations

Weight loss surgery can be invasive and there is a risk of postoperative complications.15 These risks vary depending on the surgery type.15 Typical surgical complications include bleeding, herniation, peritonitis, deep vein thrombosis and post-operative vitamin malabsorption among others.15,21 Some of these complications can be more serious than others but overall, peri-operative mortality is low and occurs in less than 1%.21

Further guidance

For more guidance on Bariatric Surgery, see page 131 of the AACE/ACE Guidelines (2016). 

Below, you can also find a practical overview of the appropriate suggested obesity therapy, based on your diagnosis and complication-specific staging.

Infographic showing diagnosis and medical management of obesity.
Reprinted from Endocrine Practice, Vol 22, Garvey et al., "Treatment Goals Based on Diagnosis in the Medical Management of Patients with Obesity", 1-203, Copyright (2016), with permission from the American Association of Clinical Endocrinologists. Available at  https://journals.aace/doi/10.4158/EP161365.GL.

You can download practical step-by-step guides for the treatment of both obesity in adults and in children by clicking the Download button.

If you found these resources valuable, click on the envelope icon above to share them with your colleagues, and support other medical professionals in their daily practice.


1. Caterson I.D., Alfadda A.A., Auerbach P. et al. Gaps to bridge: Misalignment between perception, reality and actions in obesity. Diabetes Obes Metab. 2019; 21:1914-1924.

2. Durrer Schutz D., Busetto L., Dicker D., et al. European Practical and Patient-Centred Guidelines for Adult Obesity Management in Primary Care. Obes Facts. 2019;12:40–66.

3. Garvey W.T., Mechanick J.I., Brett E.M., et al. American Association of Clinical Endocrinologists and American College of Endocrinology Comprehensive Clinical Practice Guidelines for Medical Care of Patients with Obesity. Endocr Pract. 2016;22(Suppl 3):1–203.

4. Yumuk V., Tsigos C., Fried M., et al. European Guidelines for Obesity Management in Adults. Obesity Facts. 2015;8:402–424.

5. Wadden T., Webb V., Moran C., Bailer B. Lifestyle Modification for Obesity. Circulation. 2012;125(9):1157-1170.

6. Johns D., Hartmann-Boyce J., Jebb S.A., et al. Diet or Exercise Interventions vs. Combined Behavioral Weight Management Programs: A Systematic Review and Meta-Analysis of Direct Comparisons. J Acad Nutr Diet. 2014;114:1557–1568.

7. Wharton S, Lau D, Vallis M, Sharma A, Biertho L, Campbell-Scherer D et al. Obesity in adults: a clinical practice guideline. Canadian Medical Association Journal. 2020;192(31):E875-E891.

8. Mann T., Tomiyama A.J., Westling E., et al. Medicare's search for effective obesity treatments: diets are not the answer. Am Psychol. 2007;62:220–233.

9. Jensen M.D., Ryan D.H., Apovian C.M., et al. 2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and The Obesity Society. Circulation. 2014;129:S102–138.

10. Rye P., Modi R., Cawsey S., et al. Efficacy of high-dose liraglutide as an adjunct for weight loss in patients with prior bariatric surgery. Obesity Surgery. 2018;28:3553–3558.

11. Busetto L., Dicker D., Azran C., et al. Practical Recommendations of the Obesity Management Task Force of the European Association for the Study of Obesity for the Post-Bariatric Surgery Medical Management. Obesity Facts. 2017;10:597–632.

12. Kushner R. Weight Loss Strategies for Treatment of Obesity: Lifestyle Management and Pharmacotherapy. Prog Cardiovasc Dis. 2018;61:246­–252.

13. Yanovski S., Yanovski J. Long-term Drug Treatment for Obesity. JAMA. 2014;311(1):74.

14. Li M. and Cheung B.M. Pharmacotherapy for obesity. Br J Clin Pharmacol. 2009;68:804–810.

15. American Society for Metabolic and Bariatric Surgery (ASMBS) website. Bariatric surgery procedures. Available at: https://asmbs.org/patients/bariatric-surgery-procedures. Last accessed: May 2021.

16. Courcoulas A., Christian N., Belle S., et al. Weight change and health outcomes at 3 years after bariatric surgery among individuals with severe obesity. JAMA. 2013;310:2416–25.

17. Berry M., Urrutia, Lamoza P., et al. Sleeve Gastrectomy Outcomes in Patients with BMI Between 30 and 35–3 Years of Follow-Up. Obes Surg. 2018;28:649–55.

18. Magro D., Geloneze B., Delfini R., Pareja B., Callejas F., Pareja J. Long-term Weight Regain after Gastric Bypass: A 5-year Prospective Study. Obesity Surgery. 2008;18(6):648-651.

19. Cooper T., Simmons E., Webb K., Burns J., Kushner R. Trends in Weight Regain Following Roux-en-Y Gastric Bypass (RYGB) Bariatric Surgery. Obesity Surgery. 2015;25(8):1474-1481.

20. Wolfe B., Kvach E., Eckel R. Treatment of Obesity. Circulation Research. 2016;118(11):1844-1855.

21. Kassir R., Debs T., Blanc P., et al. Complications of bariatric surgery: Presentation and emergency management. International Journal of Surgery. 2016;27:77-81.

HQ21OB00066, Approval date: October 2021

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