Lifestyle advice is important in any obesity treatment modality, but a lifestyle intervention is more than just advice and can be a modality on its own. The value of a lifestyle intervention as a neo-adjuvant treatment in metabolic surgery trajectory has been suggested as an option in a previous guideline. However, it remained unclear if and when it should be added to the already existing program, typically including lifestyle advice. New literature on the effectiveness of lifestyle programs surrounding metabolic surgery has emerged, potentially providing more definitive recommendations.

^1. Risk of Bias: serious. Lack of details on possible blinding of outcome assessors and incorrect blinding of patients in several studies. Lack of details on allocation concealment (Paul, 2022). Incomplete/lack of details on results (Kalarchian, 2016) Imprecision: Very serious. Inconsistent results between studies, includes possibility of benefit or harm and no effect.

^2. Risk of Bias: serious. Lack of details on possible blinding of outcome assessors and incorrect blinding of patients in several studies. Lack of details on allocation concealment (Paul, 2022). Imprecision: Very serious. Overlap of the 95% CI with the minimal clinically important difference, i.e. boundary of CI includes possibility of benefit or harm and no effect. Only data from one small study per (sub) outcome.

Description of studies

Kalarchian (2016) performed an RCT in the United States to evaluate the efficacy of a 6-month preoperative behavioral lifestyle intervention regarding weight loss. Adult patients who were seeking bariatric surgery were selected from a medical center. Exclusion criteria included uncontrolled psychiatric symptomatology, pregnancy/lactation, medication known for affecting body weight and diagnosis of genetic obesity syndrome. A total of 240 patients were randomized into a lifestyle intervention group or a standard care group (see Table 2).

Paul (2022) performed an RCT in the Netherlands to investigate the efficacy of a 10-week CBT intervention prior to bariatric surgery. Patients aged 21-65 years were selected from two general hospitals and were included if passing the preoperative screening and currently on the waiting list for bariatric surgery. Exclusion criteria included current psychological/psychiatric or dietary treatment or having psychiatric comorbidity (incl. suicidality, substance use). A total of 130 patients were randomized into a CBT-intervention group or a standard care group (see Table 2).

Table 2. Characteristics of included studies

*For further details, see risk of bias table in the appendix

Results

Weight loss

Kalarchian (2016) reported on weight loss as percentage weight loss pre-surgery (but after the intervention), at 6 months, 12 months and 24 months after surgery. See Table 3 for the results. No standard errors or standard deviations for the effect estimated were reported. Therefore, the difference including confidence interval between the groups and the clinical relevance could not be calculated.

Table 3. Mean weight loss (%) pre-surgery and at follow up in both study groups (Kalarchian, 2016)

Paul (2022) reported on weight loss as percentage weight loss pre-surgery (but after the lifestyle intervention), at 1 year, 3 years and 5 years after surgery. See Table 4 for the results. Observed differences were not clinically relevant.

Table 4. Mean weight loss (%) and differences at pre-surgery and at follow-up between study groups (Paul, 2022)

Obesity-related complications

No results reported.

Quality of life

Paul (2022) reported on quality of life by the short version of the World Health Organization Quality of Life (WHOQoL-BREF). The results were reported for four subscales (physical and psychological health, social relations and environment). The total score ranges from 26 (best) to 130 (worst). See Table 5 for the results. Observed differences were not clinically relevant.

Table 5. Mean scores and differences between study groups in quality of life, measured by WHO-QoL (Paul, 2022)

Psychopathology

Paul (2022) reported on psychopathology by the Quick Inventory of Depressive Symptomatology Self-Report (QIDS-SR). The score ranges from 1 (best) to 27 (worst). See Table 6 for the results.

Observed differences were not clinically relevant.

Table 6. Mean scores and differences between study groups in psychopathology, measured by QIDS-SR (Paul, 2022).

• Eating disorders

Paul (2022) reported on the outcome eating disorders by the Eating Disorder Examination Questionnaire (EDE-Q). The scores range from 0 (best) to 6 (worst). See Table 7 for the results.

Table 7. Mean scores and differences between study groups in eating disorder, measured by EDE-Q (Paul, 2022)

Emotional eating

No evidence was found regarding the outcome measure emotional eating.

A systematic review of the literature was performed to answer the following question(s):

What is the effectivity of structured lifestyle intervention program (including coaching, with at least a dietary and exercise component) in adult patients with (severe) obesity who need to undergo metabolic surgery?

Table 1. PICO

¹Including motivational interviewing, self-monitoring, learning coping strategies, CBT components, stimulus control, behavioral contracts, reward systems, goal-setting techniques, supermarket visits, cooking classes, food diary discussions, strength training, stress management training, mindfulness-based intervention, sleep interventions, emotional eating interventions

Relevant outcome measures

The guideline panel considered weight loss after metabolic surgery as a critical outcome measure for decision making, and obesity-related complications, quality of life, psychopathology and emotional eating as important outcome measures for decision making.

A priori, the guideline panel did not define the outcome measures listed above but used the definitions used in the studies.

The guideline panel defined the following thresholds as a minimal clinically (patient) important difference:

• Weight loss: Absolute difference of 5%.
• Obesity-related complications:
  • Systolic blood pressure (SBP): 3 mmHg.
  • Diastolic blood pressure (DBP): 2 mmHg.
  • LDL: 5 mg/dL.
  • HDL: 2 mg/dL.
  • HbA1c: 0.5%.
  • Other complications (inc. triglycerides, total cholesterol): 25% difference (RR <0,75 of >1,25).
• Quality of life (Warkentin, 2014):
  • EQ-5D Index: (MCID = 0.03) and Visual Analog Scale (VAS; MCID = 10) (Warkentin, 2014).
  • Impact of Weight on Quality of Life (IWQOL)-Lite total score (MCID = 12)  (Warkentin, 2014).
  • SF-36: Difference of 11.3 point on total score (Longo, 2025).
  • WHOQoL: Difference of 1 point (Den Oudsten, 2013)
• Psychopathology
  • PHQ-9: Difference of 3 points (Lynch, 2021).
  • BDI-II: Difference of 3 points (based on NICE Clinical guideline on Depression, 2004).
  • Eating disorders: 25% difference (RR<0,75 or 1,25) (standard boundaries)
• Emotional eating: 25% difference (RR <0,75 or >1,25) (standard boundaries).

Search and select (Methods)

A systematic literature search was performed by a medical information specialist using the following bibliographic databases: Embase.com and Ovid/Medline. Both databases were searched from 2005 to the 2nd of December 2025 for systematic reviews and RCTs. Systematic searches were completed using a combination of controlled vocabulary/subject headings (e.g., Emtree-terms, MeSH) wherever they were available and natural language keywords. The overall search strategy was derived from the following primary search concepts: (1) metabolic surgery; (2) lifestyle intervention. Duplicates were removed using EndNote software. After deduplication and removing of retracted articles a total of 3216 records were imported for title/abstract screening. Titles and abstracts were screened using the ASReview software. The settings ELAS u4 (TF-IDF and SVM) were used. The articles were subsequently screened by the guideline methodologist, using the following stopping rule: stop after 10% of the total set subsequent exclusions (indicating all relevant articles have been screened). Initially, only systematic reviews until 2020 were selected. A total of 39 studies were selected based on title and abstract screening. After reading the full text, 38 studies were excluded (see the exclusion table under the tab ‘Evidence Tables).

Note: The search was performed for both preoperative and postoperative lifestyle intervention around metabolic surgery. The results of postoperative lifestyle interventions are described in another module.

For the current module on preoperative lifestyle intervention, one systematic review was selected as starting point (Marshall, 2020). This review focused on both preoperative and postoperative interventions. Only one of the included studies could be included in the current literature analysis on preoperative interventions (Kalarchian, 2016). This was due to absence of either a dietary or physical component, a too short follow-up (less than 10 weeks), a high loss to follow-up (≥ 50%), or a non-randomized design. The literature search was performed until July 2018.

Additionally, selection was performed for RCT’s published in July 2018 or after (n = 952). This selection was also performed with the ASReview software as described above. Initially, 22 studies were selected based on title and abstract screening. After reading the full text, 20 studies were excluded (see the exclusion table under the tab ‘Evidence Tables) and 2 studies (of three trials) were included. Important study characteristics and results are summarized in table 2. The assessment of the risk of bias is summarized in the risk of bias tables (under the tab ‘Evidence Tables’).

1. Aarts F, Geenen R, Gerdes VE, van de Laar A, Brandjes DP, Hinnen C. Attachment anxiety predicts poor adherence to dietary recommendations: an indirect effect on weight change 1 year after gastric bypass surgery. Obes Surg. 2015 Apr;25(4):666-72. doi: 10.1007/s11695-014-1423-7. PMID: 25204408.
2. de Jong MMC, Hinnen C. Bariatric surgery in young adults: a multicenter study into weight loss, dietary adherence, and quality of life. Surg Obes Relat Dis. 2017 Jul;13(7):1204-1210. doi: 10.1016/j.soard.2017.02.026. Epub 2017 Mar 7. PubMed PMID: 28396129.
3. Den Oudsten BL, Zijlstra WP, De Vries J. The minimal clinical important difference in the World Health Organization Quality of Life instrument--100. Support Care Cancer. 2013 May;21(5):1295-301. doi: 10.1007/s00520-012-1664-8. Epub 2012 Dec 1. PMID: 23203652.
4. Dutch Audit for Treatment of Obesity (DATO). Nienhuijs SW, Akpinar EO. JAARVERSLAG 2020. Available at https://support.mrdm.com/wp-content/uploads/2024/01/DATO-jaarverslag-2020.pdf.
5. Kalarchian MA, Marcus MD, Courcoulas AP, Cheng Y, Levine MD. Preoperative lifestyle intervention in bariatric surgery: a randomized clinical trial. Surg Obes Relat Dis. 2016 Jan;12(1):180-7. doi: 10.1016/j.soard.2015.05.004. Epub 2015 May 8. PMID: 26410538; PMCID: PMC5041299.
6. Longo UG, Campi S, De Salvatore S, Piergentili I, Bandini B, Lalli A, Ammendolia V, de Sire A, Papalia R. Minimum clinically important difference of 36-item short form health survey (SF-36) to assess post-surgery quality of life in knee osteoarthritis. J Back Musculoskelet Rehabil. 2025 Jan;38(1):158-164. doi: 10.1177/10538127241296344. Epub 2025 Jan 9. PMID: 39970460.
7. Lynch CP, Cha EDK, Jenkins NW, Parrish JM, Mohan S, Jadczak CN, Geoghegan CE, Singh K. The Minimum Clinically Important Difference for Patient Health Questionnaire-9 in Minimally Invasive Transforaminal Interbody Fusion. Spine (Phila Pa 1976). 2021 May 1;46(9):603-609. doi: 10.1097/BRS.0000000000003853. PMID: 33290370.
8. Marshall S, Mackay H, Matthews C, Maimone IR, Isenring E. Does intensive multidisciplinary intervention for adults who elect bariatric surgery improve post-operative weight loss, co-morbidities, and quality of life? A systematic review and meta-analysis. Obes Rev. 2020 Jul;21(7):e13012. doi: 10.1111/obr.13012. Epub 2020 Mar 20. PMID: 32196906.
9. NCCMH (2004). Depression: Management of Depression in Primary and Secondary Care. British Psychological Society and Royal College of Psychiatrists: Leicester and London.
10. Paul L, van der Heiden C, van Hoeken D, Deen M, Vlijm A, Klaassen R, Biter LU, Hoek HW. Three- and five-year follow-up results of a randomized controlled trial on the effects of cognitive behavioral therapy before bariatric surgery. Int J Eat Disord. 2022 Dec;55(12):1824-1837. doi: 10.1002/eat.23825. Epub 2022 Oct 21. PMID: 36268671; PMCID: PMC10092022.
11. Warkentin LM, Majumdar SR, Johnson JA, Agborsangaya CB, Rueda-Clausen CF, Sharma AM, Klarenbach SW, Karmali S, Birch DW, Padwal RS. Weight loss required by the severely obese to achieve clinically important differences in health-related quality of life: two-year prospective cohort study. BMC Med. 2014 Oct 15;12:175. doi: 10.1186/s12916-014-0175-5. PMID: 25315502; PMCID: PMC4212133.