Management

Diets for Weight Loss

Editors: Fatima Cody Stanford MD, MPH, MPA, FAAP, FACP, FAHA, FTOS; Zbigniew Fedorowicz PhD, MSc, DPH, BDS, LDSRCS; Alan Ehrlich MD, FAAFP

References

General References Used

The references listed below are used in this DynaMed topic primarily to support background information and for guidance where evidence summaries are not felt to be necessary. Most references are incorporated within the text along with the evidence summaries.

  1. Locke A, Schneiderhan J, Zick SM. Diets for Health: Goals and Guidelines. Am Fam Physician. 2018 Jun 1;97(11):721-728, commentary can be found in Am Fam Physician 2019 Feb 1;99(3):142.
  2. Garvey WT, Mechanick JI, Brett EM, et al., Reviewers of the AACE/ACE Obesity Clinical Practice Guidelines. American Association of Clinical Endocrinologists and American College of Endocrinology Comprehensive Clinical Practice Guidelines for Medical Care of Patients with Obesity. Endocr Pract. 2016 Jul;22 Suppl 3:1-203.
  3. Academy of Nutrition and Dietetics (AND). 2021-2022 Adult Weight Management Evidence-Based Nutrition Practice Guideline (update). (AND Evidence Analysis Library 2022) .
  4. Academy of Nutrition and Dietetics (AND). 2014 Adult Weight Management Evidence-Based Nutrition Practice Guideline. (AND Evidence Analysis Library 2014) .

Recommendation Grading Systems Used

  • American Association of Clinical Endocrinologists/American College of Endocrinology (AACE/ACE) grading system
    • grades of recommendation
      • Grade A - best evidence level 1, or best evidence level 2 but adjusted upward for positive subjective factors
      • Grade B - best evidence level 2, or best evidence level 1 adjusted downward for negative subjective factors, or best evidence level 3 adjusted upward for positive subjective factors
      • Grade C - best evidence level 3, or best evidence level 2 adjusted downward for negative subjective factors, or best evidence level 4 adjusted upward for positive subjective factors
      • Grade D - best evidence level 4, or best evidence level 3 adjusted downward for negative subjective factors, or < two-thirds consensus (regardless of evidence level)
    • levels of evidence
      • Level 1 - randomized trials or meta-analysis of randomized trials
      • Level 2 - nonrandomized controlled trial, prospective cohort study, retrospective case-control study, or meta-analysis of these types of studies
      • Level 3 - cross-sectional study, surveillance study, consecutive case series, or single case reports
      • Level 4 - no evidence (theory, opinion, consensus, review, or preclinical study)
    • PubMed27472012Endocrine practice : official journal of the American College of Endocrinology and the American Association of Clinical EndocrinologistsEndocr Pract20160701227842-84842Reference - AACE/ACE comprehensive clinical practice guidelines for medical care of patients with obesity (Endocr Pract 2016 Jul;22 Suppl 3:1), executive summary can be found at Endocr Pract 2016 Jul;22(7):842
  • Academy of Nutrition and Dietetics (AND) criteria for recommendation rating
    • criteria for recommendation ratings
      • Strong recommendation - benefits of approach clearly exceed harms (or vice versa) and quality of supporting evidence is excellent/good; recommendation may be based on lesser evidence when high-quality evidence impossible to obtain and anticipated benefits strongly outweigh harms
      • Fair recommendation - benefits exceed harms (or vice versa) but quality of evidence not as strong; recommendation may be based on lesser evidence when high-quality evidence impossible to obtain and anticipated benefits outweigh harms
      • Weak recommendation - quality of evidence is suspect or well-done studies show unclear advantage to one approach opposed to another
      • Consensus - expert opinion supports recommendation despite inconsistent results from available scientific evidence or lack of controlled trials
      • Insufficient evidence - lack of pertinent evidence and/or unclear balance between benefits and harms
    • category of recommendation statement
      • Imperative - broadly applicable to target population and do not impose restraints on pertinence
      • Conditional - clearly define specific situations or populations
    • Reference - AND guideline on adult weight management (AND Evidence Analysis Library 2014)
  • Academy of Nutrition and Dietetics (AND) criteria for recommendation rating
    • strength of recommendation
      • Strong (level 1) - most individuals should receive recommended course of action
      • Weak (level 2) - different choices appropriate for different patients; clinician must take time needed to help patient arrive at management decision consistent with their values and preferences, possibly using decision aids
      • Consensus - evidence from systematic review unavailable or unclear; recommendation based on clinical expertise and experience with differing patient values, so clinician must help patient arrive at management decision consistent with their values or preferences
    • certainty of evidence
      • High (A) - very confident true effect lies close to that of effect estimate
      • Moderate (B) - moderate confidence in effect estimate; true effect likely close to effect estimate, but possibly differs that substantially
      • Low (C) - limited confidence in effect estimate; true effect may differ substantially from effect estimate
      • Very low (D) - little confidence in effect estimate; true effect likely substantially different from effect estimate
    • category of recommendation statement
      • Imperative - broadly applicable to target population; does not impose restraints on pertinence
      • Conditional - clearly defines specific situations or populations
    • Reference - AND guideline update on adult weight management (AND Evidence Analysis Library 2022)
  • United States Preventive Services Task Force (USPSTF) grades of recommendation (after July 2012)
    • Grade A - USPSTF recommends the service with high certainty of substantial net benefit
    • Grade B - USPSTF recommends the service with high certainty of moderate net benefit or moderate certainty of moderate-to-substantial net benefit
    • Grade C - USPSTF recommends selectively offering or providing the service (based on professional judgment and patient preference) with at least moderate certainty of small net benefit
    • Grade D - USPSTF recommends against providing the service with moderate-to-high certainty of no net benefit or harms outweighing benefits
    • Grade I - insufficient evidence to assess balance of benefits and harms
    • Reference - USPSTF Grade Definitions

Synthesized Recommendation Grading System for DynaMed Content

  • The DynaMed Team systematically monitors clinical evidence to continuously provide a synthesis of the most valid relevant evidence to support clinical decision-making (see 7-Step Evidence-Based Methodology).
  • Guideline recommendations summarized in the body of a DynaMed topic are provided with the recommendation grading system used in the original guideline(s) and allow users to quickly see where guidelines agree and where guidelines differ from each other and from the current evidence.
  • In DynaMed content, we synthesize the current evidence, current guidelines from leading authorities, and clinical expertise to provide recommendations to support clinical decision-making in the Overview & Recommendations section.
  • We use the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to classify synthesized recommendations as Strong or Conditional.
    • Strong recommendations may be used when, based on the available evidence, clinicians (without conflicts of interest) consistently have a high degree of confidence that the desirable consequences (health benefits, decreased costs and burdens) outweigh the undesirable consequences (harms, costs, burdens).
    • Conditional recommendations may be used when, based on the available evidence, clinicians believe that desirable and undesirable consequences are finely balanced, or appreciable uncertainty exists about the magnitude of expected consequences (benefits and harms).
    • Conditional recommendations may be used when clinicians disagree in judgments of the relative benefit and harm or have limited confidence in their judgments.
    • Conditional recommendations may also be used when the range of patient values and preferences suggests that informed patients are likely to make different choices.
  • DynaMed synthesized recommendations (in the Overview & Recommendations section) are determined with a systematic methodology.
    • Recommendations are explicitly labeled as Strong recommendations or Conditional recommendations when a qualified organization has explicitly deliberated on making such a recommendation.
    • Recommendations are phrased to match the strength of recommendation.
      • Strong recommendations use "should do" phrasing, or phrasing implying an expectation to perform the recommended action for most patients.
      • Conditional recommendations use "consider" or "suggested" phrasing.
    • Recommendations are verified by ≥ 1 editor with methodological expertise, not involved in recommendation drafting or development, with explicit confirmation that Strong recommendations are adequately supported.
    • Recommendations are published only after consensus is established with agreement in phrasing and strength of recommendation by all editors.
    • If recommendations are questioned during peer review or post publication by a qualified individual, or reevaluation is warranted based on new information detected through systematic literature surveillance, the recommendation is subject to additional internal review.

DynaMed Editorial Process

  • DynaMed topics are created and maintained by the DynaMed Editorial Team and adhere to evidence-based methodology and inclusive language standards.
  • All editorial team members and reviewers have declared that they have no financial or other competing interests related to this topic, unless otherwise indicated.
  • DynaMed content includes Practice-Changing Updates, with support from our partner, McMaster University.

Special Acknowledgements

  • DynaMed topics are written and edited through the collaborative efforts of the above individuals. Deputy Editors, Section Editors, and Topic Editors are active in clinical or academic medical practice. Recommendations Editors are actively involved in development and/or evaluation of guidelines.
  • Editorial Team role definitions
    Topic Editors define the scope and focus of each topic by formulating a set of clinical questions and suggesting important guidelines, clinical trials, and other data to be addressed within each topic. Topic Editors also serve as consultants for the internal DynaMed Editorial Team during the writing and editing process, and review the final topic drafts prior to publication.
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    Recommendations Editors provide explicit review of Overview and Recommendations sections to ensure that all recommendations are sound, supported, and evidence-based. This process is described in "Synthesized Recommendation Grading."
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DynaMed Levels of Evidence

Quickly find and determine the quality of the evidence.

DynaMed provides easy-to-interpret Level of Evidence labels so users can quickly find and determine the quality of the best available evidence. Evidence may be labeled in one of three levels:

1Level 1 (likely reliable) Evidence
Representing research results addressing clinical outcomes and meeting an extensive set of quality criteria which minimizes bias.
There are two types of conclusions which can earn a Level 1 label: levels of evidence for conclusions derived from individual studies and levels of evidence for conclusions regarding a body of evidence.
2Level 2 (mid-level) Evidence
Representing research results addressing clinical outcomes, and using some method of scientific investigation, but not meeting the quality criteria to achieve Level 1 evidence labeling.
3Level 3 (lacking direct) Evidence
Representing reports that are not based on scientific analysis of clinical outcomes. Examples include case series, case reports, expert opinion, and conclusions extrapolated indirectly from scientific studies.

Grades of Recommendation

Guideline producers are now frequently using classification approaches for their evidence and recommendations, and these classifications are recognized and requested by guideline users. When summarizing guideline recommendations for DynaMed users, the DynaMed Editors are using the guideline-specific classifications and providing guideline classification approach when this is done.

Download the full version of Levels of Evidence