• Participants: Adult primary-care patients (at least 18 years of age) who were overweight or obese (defined as BMI of at least 25.0kg/m²) were included. Studies of interventions targeting specific patient groups (i.e., diabetes, hypertension) were included if the study specified overweight or obesity as an inclusion criteria.
• Interventions: Studies aimed at reducing weight in overweight and obese primary-care patients were included. This encompassed behavioral interventions delivered by primary-care physicians alone or in conjunction with other personnel. Comparative trials where another intervention was compared with interventions delivered by primary-care physicians were also included. 
• Outcomes: Eligible studies included weight loss or reduction in BMI as an outcome. Weight or BMI change were chosen as the main outcomes, as studies focused on other outcomes (such as physical activity levels, nutrition changes, biochemistry data) may not provide an adequate basis for identifying effective approaches for directly addressing overweight and obesity.
• Study design: The following study designs that met the EPOC research criteria were included: Randomized controlled trial (RCT), controlled clinical trial (CCT), controlled before-and-after study (CBA) and interrupted time series (ITS).

• Surgical and pharmacological interventions, as well as studies where primary-care physicians were not involved in any component of the intervention, were excluded
• Studies not meeting the inclusion criteria, as stated.

• Recruitment: N/A
• Design: Systematic review
• Quality assessment: The EPOC quality criteria for RCT, CCT and CBA were used to assess the methodological adequacy of weight-loss interventions involving primary-care physicians and included studies. For each criterion a score of ‘yes’ was assigned if the study met the criterion, ‘no’ if it did not and ‘unclear’ if there was insufficient information to adequately decide if the criterion was met. A score out of nine for each study was reported.

Data Extraction by Two Independent Authors

• Participants and intervention: Participant characteristics (including percentage of females, age, ethnicity and mean BMI) were extracted. Information related to the intervention, number of participants in each group, retention rate, mean weight change and whether or not statistically significant weight loss was achieved was also extracted. Whether a larger percentage of participants in the Intervention Group achieved clinically significant weight loss (for the purpose of the present review, this was defined as having a weight loss of more than 5% of initial body weight) compared with the Control Group was recorded. A weight loss of 5% or more of initial body weight has been shown to result in improvements in weight-related comorbidities. Where two intervention arms existed, comparisons between Intervention and Control Group were reported.
• Intensity: Intensity of interventions were coded as ‘low’, ‘moderate’ or ‘high,’ based on frequency of contact in the first three months. An intervention was defined as high intensity if there was more than monthly contact, moderate if there was monthly contact and low if less than monthly contact occurred in the first three months of the intervention. Where there was insufficient information, intensity was coded as ‘unsure.’
• Quality assurance: All abstracts were reviewed by one researcher and full-text articles of potentially relevant articles were retrieved. As a quality assurance measure, 10% of the abstracts were reviewed and coded independently by a second reviewer. All coding for quality criteria and data extraction were carried out by two authors and differences resolved by mutual discussion.

Intervention

• Studies aimed at reducing weight in overweight and obese primary-care patients were included. This encompassed behavioral interventions delivered by primary-care physicians alone or in conjunction with other personnel.
• Comparative trials where another intervention was compared with interventions delivered by primary-care physicians were also included. 

Timing of Measurements

N/A.

Dependent Variables

• Mean weight change
• Signifigance of weight loss (loss of more than 5% initial body weight), compared to Control Group.

Independent Variables

• Participant characteristics
• Intervention vs. Control Group assignment
• Intervention intensity (low, moderat, high) based on frequency of contact in first three months.

Control Variables

Data extraction methods, as stated for systemic review.

• Initial N: 1,356 titles and abstracts reviewed (493 relevant studies; 87 intervention studies)
• Attrition (final N): 17 included intervention studies
• Age: Not defined
• Ethnicity: Not defined
• Other relevant demographics: Not defined
• Location: USA, Europe, Australia.

Key Findings

• The interventions were broadly categorized into:
  1. Lifestyle counselling delivered primarily by primary-care physicians
  2. Lifestyle counselling delivered primarily by non-primary-care physicians
  3. Multi-component intervention.
• A total of 16 different studies were included. Of these, six assessed primary care physicians’ delivery of weight-loss counselling; nine assessed weight-loss counselling delivered by non-physician personnel with monitoring by primary care physicians; one assessed a multi-component intervention.
• Overall, high-intensity weight-loss counselling by primary care physicians resulted in moderate but not clinically significant weight loss
• High-intensity weight-loss counselling delivered by non-physicians, meal replacements delivered in conjunction with dietitian counselling and referral to commercial weight-loss center programs accompanied by regular monitoring by a primary care physician were effective in producing clinically significant weight loss
• Dietitian-delivered care appeared effective in producing weight loss regardless of level of intervention intensity.

• Overall, there were few studies on this topic and the methodological rigor of some included studies was poor
• Results suggest that counselling delivered by non-physicians (face-to-face or telephone) with support from primary-care physicians is effective in producing weight loss
• Additional studies assessing the effectiveness and acceptability of potential interventions are needed to confirm these findings.