Pediatric Weight Management

PWM: Physical Activity and Inactivity of Youth (2006)


Dietz WH, Gortmaker SL. Do we fatten our children at the television set? Obesity and television viewing in children and adolescents. Pediatrics 1985;75:807-812

PubMed ID: 3873060
Study Design:
Cross-Sectional Study
D - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To determine whether excessive fatness was associated with increased television viewing in 2 cross- sectional samples and 1 longitudinal sample of children and adolescents in the US and whether this association would persist when other variables known to influence childhood obesity were controlled.

Inclusion Criteria:

Those who agreed to participate and whom had complete data.

Exclusion Criteria:

Not specified

Description of Study Protocol:

6965 6 to 11 year olds studied in 1963 and 1965 (cycle II).


6671 12 to 17 year olds studied in 1966 to 1970 (cycle III).  2153 subjects in cycle III had also been studied in cycle II.

Statistical Analyses:

Prevalence of obesity and super-obesity at different levels of reported TV watching were compared using chi square, simple regression and associated F tests.

Weighted Regression was used to control for environmental, economic and family variables.  F tests were used to examine the significance. 

In longitudinal analyses, weighted stepwise regression was used to examine the effect of television viewing on subsequent obesity in cycle III after controlling for obesity and superobesity in cycle II.

Data Collection Summary:

Dependent Variables

  • Obesity - Skinfolds (Triceps = or greater than the 85th percentile)

Independent Variables

  • Age group
  • Television watching – hours per day (parental report cycle II and self-report cycle III)


  • Age (6-11) and (12-17)
  • Obesity
  • Region
  • Season
  • Population density
  • SES
  • Family variables
Description of Actual Data Sample:

6965 6 to 11 year olds studied in 1963 and 1965 (cycle II)

6671 12 to 17 year olds studied in 1966 to 1970 (cycle III). 2153 subjects in cycle III had also been studied in cycle II.

Summary of Results:

In 6-11 year olds, there were significant associations between time spent watching TV and the prevalence of obesity (p<.01) and superobesity (p<.02).

In 12-17 year olds there were also significant associations with obesity (P = .0001) and superobesity (P<.0)01)

There was evidence of a dose response effect as the prevalence of obesity increased 2% for every additional hour spent watching TV. This relationship persisted when obesity, region, season, population density, race, socioeconomic class, and a variety of family variables were controlled for.

In the longitudinal analyses, controlling for obesity status reduced the associations but they remained statistically significant.

Author Conclusion:

The results indicate highly significant and reproducible associations of television watching and obesity in children and adolescents. In the regression analysis, only prior obesity had a larger effect than television viewing on the prevalence of obesity.

These results fulfill many of the criteria for a causal relationship.

Overall, the results indicate that watching television may cause obesity in at least some children and adolescents.

Funding Source:
University/Hospital: New England Medical Center, Harvard School of Public Health
Reviewer Comments:


  • The study used a large representative sample of non-institutionalized people. 
  • Analyses looked at the data both cross-sectionally as well as longitudinally in an attempt to determine a causal relationship. Obesity assessed with triceps skinfold.


  • Differences in source osfassessment of TV viewing in cycle II and cycle II.  Could influence longitudinal results.
Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) N/A
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? N/A
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? N/A
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) N/A
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? N/A
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? Yes
  2.2. Were criteria applied equally to all study groups? N/A
  2.3. Were health, demographics, and other characteristics of subjects described? No
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) Yes
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? Yes
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? N/A
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? N/A
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) N/A
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? N/A
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
  6.8. In diagnostic study, were details of test administration and replication sufficient? Yes
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? N/A
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? N/A
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? N/A
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? N/A
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? N/A
  8.2. Were correct statistical tests used and assumptions of test not violated? N/A
  8.3. Were statistics reported with levels of significance and/or confidence intervals? N/A
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  8.6. Was clinical significance as well as statistical significance reported? N/A
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? N/A
  9.2. Are biases and study limitations identified and discussed? N/A
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? N/A
  10.2. Was the study free from apparent conflict of interest? N/A