Note from the National Guideline Clearinghouse (NGC) and the American Dietetic Association (ADA): Several recommendations of this guideline were based on the evidence analysis done by the National Heart Lung and Blood Institute (NHLBI). The NHLBI guidelines were based on a systematic review of the literature and the evidence statements and recommendations were categorized by levels of evidence ranging from A to D. Refer to the NHLBI Web site for definitions of those grades.
Ratings for the strength of the recommendations (Strong, Fair, Weak, Consensus, Insufficient Evidence), conclusion grades (I-V), and statement labels (Conditional versus Imperative) are defined at the end of "Major Recommendations."
Adult Weight Management (AWM) Classification of Overweight and Obesity
AWM: Body Mass Index (BMI)-Classification of Overweight and Obesity
BMI and waist circumference should be used to classify overweight and obesity, estimate risk for disease, and to identify treatment options. BMI and waist circumference are highly correlated to obesity or fat mass and risk of other diseases (NHLBI report).
Fair, Imperative
AWM: Body Weight-Classification of Overweight and Obesity
Body weight and waist circumference should be used to determine the effectiveness of therapy in the reassessment. BMI and waist circumference are highly correlated to obesity or fat mass (NHLBI report).
Fair, Imperative
Recommendation Strength Rationale
- NHLBI Evidence Categories of C and D
Adult Weight Management (AWM) Comprehensive Weight Management Program
AWM: Comprehensive Weight Management Program
Weight loss and weight maintenance therapy should be based on a comprehensive weight management program including diet, physical activity, and behavior therapy. The combination therapy is more successful than using any one intervention alone.
Strong, Imperative
Recommendation Strength Rationale
- NHLBI Evidence Category of A
Adult Weight Management (AWM) Optimal Length of Weight Management Therapy
AWM: Optimal Length of Therapy
Medical nutrition therapy for weight loss should last at least 6 months or until weight loss goals are achieved, with implementation of a weight maintenance program after that time. A greater frequency of contacts between the patient and practitioner may lead to more successful weight loss and maintenance.
Strong, Imperative
Recommendation Strength Rationale
- NHLBI Evidence Categories of A, B, C, D
Adult Weight Management (AWM) Realistic Weight Goal Setting
AWM: Realistic Weight Goals
Individualized goals of weight loss therapy should be to reduce body weight at an optimal rate of 1 to 2 lbs per week for the first 6 months and to achieve an initial weight loss goal of up to 10% from baseline. These goals are realistic, achievable, and sustainable.
Strong, Imperative
Recommendation Strength Rationale
- NHLBI Evidence Categories of A and B
Adult Weight Management (AWM) Determination of Resting Metabolic Rate
AWM: Determining Energy Needs
Estimated energy needs should be based on resting metabolic rate (RMR). If possible, RMR should be measured (e.g., indirect calorimetry). If RMR cannot be measured, then the Mifflin-St. Jeor equation using actual weight is the most accurate for estimating RMR for overweight and obese individuals.
Refer to the original guideline document for the Mifflin-St. Jeor equations.
Strong, Conditional
Recommendation Strength Rationale
- Conclusion statements are Grades I and II
Adult Weight Management (AWM) Reduced Calorie Diets
AWM: Reduced Calorie Diet
An individualized reduced calorie diet is the basis of the dietary component of a comprehensive weight management program. Reducing dietary fat and/or carbohydrates is a practical way to create a caloric deficit of 500 to 1000 kilocalories (kcals) below estimated energy needs and should result in a weight loss of 1 to 2 lbs per week.
Strong, Imperative
Recommendation Strength Rationale
- NHLBI Evidence Categories of A
Adult Weight Management (AWM) Eating Frequency and Patterns
AWM: Eating Frequency and Patterns
Total caloric intake should be distributed throughout the day, with the consumption of 4 to 5 meals/snacks per day including breakfast. Consumption of greater energy intake during the day may be preferable to evening consumption.
Fair, Imperative
Recommendation Strength Rationale
- Conclusion statements are Grade II
Adult Weight Management (AWM) Portion Control
AWM: Portion Control
Portion control should be included as part of a comprehensive weight management program. Portion control at meals and snacks results in reduced energy intake and weight loss.
Fair, Imperative
Recommendation Strength Rationale
- Conclusion statements are Grade III
Adult Weight Management (AWM) Meal Replacements
AWM: Meal Replacements
For people who have difficulty with self selection and/or portion control, meal replacements (e.g., liquid meals, meal bars, calorie-controlled packaged meals) may be used as part of the diet component of a comprehensive weight management program. Substituting one or two daily meals or snacks with meal replacements is a successful weight loss and weight maintenance strategy.
Strong, Conditional
Recommendation Strength Rationale
- Conclusion statements are Grade I
Adult Weight Management (AWM) Nutrition Education
AWM: Nutrition Education
Nutrition education should be individualized and included as part of the diet component of a comprehensive weight management program. Short term studies show that nutrition education (e.g., reading nutrition labels, recipe modification, cooking classes) increases knowledge and may lead to improved food choices.
Fair, Imperative
Recommendation Strength Rationale
- Conclusion statements are Grade III
Adult Weight Management (AWM) Low Glycemic Index Diets
AWM: Low Glycemic Index Diets
A low glycemic index diet is not recommended for weight loss or weight maintenance as part of a comprehensive weight management program, since it has not been shown to be effective in these areas.
Strong, Imperative
Recommendation Strength Rationale
- Conclusion statement is Grade I
Adult Weight Management (AWM) Dairy/Calcium and Weight Management
AWM: Dairy/Calcium and Weight Management
In order to meet current nutritional recommendations, incorporate 3 to 4 servings of low fat dairy foods a day as part of the diet component of a comprehensive weight management program. Research suggests that calcium intake lower than recommended levels is associated with increased body weight. However, the effect of dairy and/or calcium at or above recommended levels on weight management is unclear.
Refer to the original guideline document for dietary reference intakes for calcium.
Fair, Imperative
Recommendation Strength Rationale
- Conclusion statement is Grade III
Adult Weight Management (AWM) Low Carbohydrate Diet
AWM: Low Carbohydrate Diet
Having patients focus on reducing carbohydrates rather than reducing calories and/or fat may be a short term strategy for some individuals. Research indicates that focusing on reducing carbohydrate intake (<35% of kcals from carbohydrates) results in reduced energy intake. Consumption of a low-carbohydrate diet is associated with a greater weight and fat loss than traditional reduced calorie diets during the first 6 months, but these differences are not significant after 1 year.
Fair, Conditional
Recommendation Strength Rationale
- Conclusion statement is Grade II
Adult Weight Management (AWM) Physical Activity
AWM: Physical Activity
Physical activity should be part of a comprehensive weight management program. Physical activity level should be assessed and individualized long-term goals established to accumulate at least 30 minutes or more of moderate intensity physical activity on most, and preferably, all days of the week, unless medically contraindicated. Physical activity contributes to weight loss, may decrease abdominal fat, and may help with maintenance of weight loss.
Strong, Imperative
Recommendation Strength Rationale
- NHLBI Evidence Categories of A, B, and C
Adult Weight Management (AWM) Multiple Behavior Therapy Strategies
AWM: Multiple Behavior Therapy Strategies
A comprehensive weight management program should make maximum use of multiple strategies for behavior therapy (e.g., self monitoring, stress management, stimulus control, problem solving, contingency management, cognitive restructuring, and social support). Behavior therapy in addition to diet and physical activity leads to additional weight loss. Continued behavioral interventions may be necessary to prevent a return to baseline weight.
Strong, Imperative
Recommendation Strength Rationale
- NHLBI Evidence Categories of A and B
Adult Weight Management (AWM) Medication as Part of a Comprehensive Program
AWM: Use of Weight Loss Medications
Food and Drug Administration (FDA)-approved weight loss medications may be part of a comprehensive weight management program. Dietitians should collaborate with other members of the health care team regarding the use of FDA-approved weight loss medications for people who meet the NHLBI criteria. Research indicates that pharmacotherapy may enhance weight loss in some overweight and obese adults.
Strong, Imperative
Recommendation Strength Rationale
- NHLBI Evidence Categories of A, B and C
Adult Weight Management (AWM) Bariatric Surgery for Weight Loss
AWM: Bariatric Surgery for Weight Loss
Dietitians should collaborate with other members of the health care team regarding the appropriateness of bariatric surgery for people who have not achieved weight loss goals with less invasive weight loss methods and who meet the NHLBI criteria. Separate ADA evidence based guidelines are being developed on nutrition care in bariatric surgery.
Strong, Imperative
Recommendation Strength Rationale
- NHLBI Evidence Categories of B
Definitions:
Conditional versus Imperative Recommendations
Recommendations can be worded as conditional or imperative statements. Conditional statements clearly define a specific situation, while imperative statements are broadly applicable to the target population without restraints on their pertinence. More specifically, a conditional recommendation can be stated in if/then terminology (e.g., If an individual does not eat food sources of omega-3 fatty acids, then 1g of EPA and DHA omega-3 fatty acid supplements may be recommended for secondary prevention).
In contrast, imperative recommendations "require," or "must," or "should achieve certain goals," but do not contain conditional text that would limit their applicability to specified circumstances. (e.g., Portion control should be included as part of a comprehensive weight management program. Portion control at meals and snacks results in reduced energy intake and weight loss).
Levels of Evidence
| Strength of Evidence Elements |
Grade I
Good/Strong
|
Grade II
Fair
|
Grade III
Limited/Weak
|
Grade IV
Expert Opinion Only
|
Grade V
Grade Not Assignable
|
Quality
- Scientific rigor/validity
- Considers design and execution
|
Studies of strong design for question
Free from design flaws, bias and execution problems
|
Studies of strong design for question with minor methodological concerns
OR
Only studies of weaker study design for question
|
Studies of weak design for answering the question
OR
Inconclusive findings due to design flaws, bias or execution problems
|
No studies available
Conclusion based on usual practice, expert consensus, clinical experience, opinion, or extrapolation from basic research
|
No evidence that pertains to question being addressed |
Consistency
Of findings across studies
|
Findings generally consistent in direction and size of effect or degree of association, and statistical significance with minor exceptions at most |
Inconsistency among results of studies with strong design
OR
Consistency with minor exceptions across studies of weaker designs
|
Unexplained inconsistency among results from different studies
OR
Single study unconfirmed by other studies
|
Conclusion supported solely by statements of informed nutrition or medical commentators |
NA |
Quantity
- Number of studies
- Number of subjects in studies
|
One to several good quality studies
Large number of subjects studies
Studies with negative results having sufficiently large sample size for adequate statistical power
|
Several studies by independent investigators
Doubts about adequacy of sample size to avoid Type I and Type II error
|
Limited number of studies
Low number of subjects studies and/or inadequate sample size within studies
|
Unsubstantiated by published studies |
Relevant studies have not been done |
Clinical Impact
- Importance of studies outcomes
- Magnitude of effect
|
Studied outcome relates directly to the question
Size of effect is clinically meaningful
Significant (statistical) difference is large
|
Some doubt about the statistical or clinical significance of effect |
Studies outcome is an intermediate outcome or surrogate for the true outcome of interest
OR
Size of effect is small or lacks statistical and/or clinical significance
|
Objective data unavailable |
Indicates area for future research |
Generalizability
To population of interest
|
Studied population, intervention and outcomes are free from serious doubts about generalizability |
Minor doubts about generalizability |
Serious doubts about generalizability due to narrow or different study population, intervention or outcomes studied |
Generalizability limited to scope of experience |
NA |
This grading system was based on the grading system from: Greer N, Mosser G, Logan G, Wagstrom Halaas G. A practical approach to evidence grading. Jt Comm. J Qual Improv. 2000; 26:700-712. In September 2004, The ADA Research Committee modified the grading system to this current version.
Criteria for Recommendation Rating
| Statement Rating |
Definition |
Implication for Practice |
| Strong |
A Strong recommendation means that the workgroup believes that the benefits of the recommended approach clearly exceed the harms (or that the harms clearly exceed the benefits in the case of a strong negative recommendation), and that the quality of the supporting evidence is excellent/good (grade I or II)*. In some clearly identified circumstances, strong recommendations may be made based on lesser evidence when high-quality evidence is impossible to obtain and the anticipated benefits strongly outweigh the harms. |
Practitioners should follow a Strong recommendation unless a clear and compelling rationale for an alternative approach is present. |
| Fair |
A Fair recommendation means that the workgroup believes that the benefits exceed the harms (or that the harms clearly exceed the benefits in the case of a negative recommendation), but the quality of evidence is not as strong (grade II or III)*. In some clearly identified circumstances, recommendations may be made based on lesser evidence when high-quality evidence is impossible to obtain and the anticipated benefits outweigh the harms. |
Practitioners should generally follow a Fair recommendation but remain alert to new information and be sensitive to patient preferences. |
| Weak |
A Weak recommendation means that the quality of evidence that exists is suspect or that well-done studies (grade I, II, or III)* show little clear advantage to one approach versus another. |
Practitioners should be cautious in deciding whether to follow a recommendation classified as Weak, and should exercise judgment and be alert to emerging publications that report evidence. Patient preference should have a substantial influencing role. |
| Consensus |
A Consensus recommendation means that Expert opinion (grade IV)* supports the guideline recommendation even though the available scientific evidence did not present consistent results, or controlled trials were lacking. |
Practitioners should be flexible in deciding whether to follow a recommendation classified Consensus, although they may set boundaries on alternatives. Patient preference should have a substantial influencing role. |
| Insufficient Evidence |
An Insufficient Evidence recommendation means that there is both a lack of pertinent evidence (grade V)* and/or an unclear balance between benefits and harms. |
Practitioners should feel little constraint in deciding whether to follow a recommendation labeled as Insufficient Evidence and should exercise judgment and be alert to emerging publications that report evidence that clarifies the balance of benefit versus harm. Patient preference should have a substantial influencing role. |
*Conclusion statements are assigned a grade based on the strength of the evidence. Grade I is good; grade II, fair; grade III, limited; grade IV signifies expert opinion only and grade V indicates that a grade is not assignable because there is no evidence to support or refute the conclusion. The evidence and these grades are considered when assigning a rating (Strong, Fair, Weak, Consensus, Insufficient Evidence - see chart above) to a recommendation.
Adapted by the American Dietetic Association from the American Academy of Pediatrics, Classifying Recommendations for Clinical Practice Guideline, Pediatrics. 2004;114;874-877.
