NNNS: Effect on Energy Balance (Weight) (2010)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
  • To examine whether artificial sweeteners aid in the control of long-term food intake and body weight.
Inclusion Criteria:
  • Sufficient diet record-keeping
  • Signed consent form
  • Receive beverages to drink on various days
  • Weekly interview at the laboratory.
Exclusion Criteria:
  • Based on answers to questionnaires of 40-question EAT test, the 51-question Restrained Eating questionnaire and other questionniares to assess medical hisotry, food preferences, eating attitudes and dietary restraint
  • Recently or currently dieting
  • Avoiding caffeine
  • Had a family history of diabetes or were pregnant.
Description of Study Protocol:


  • Run in fall 1987 and spring 1988. Approved by the Committee on Studies Involving Human Beings at the University of Pennsylvania. Advertisements posted on local university campuses.

Statistical Analysis

  • Mean and SEM for physical charateristics, food intake, three-way ANOVAs with factors of sex, treatment and days, between-subject comparisons, triangle tests for taste tests and degrees of freedom.


  • Initial training period: RD instructed each subject on how to complete dietary records. To ensure understanding of the instructions, subjects kept a practice record for two or three days. Record was reviewed and at this stage: Six females and eight males quit and two were eliminated due to insufficient record-keeping.

Experimental Procedure

  • Each subject maintained a dietary record continuously for nine weeks. During this period, they received, in counter-balanced order for three weeks each, soda sweetned with APM, soda sweetened with high-fructose corn syrup (HFCS) or no experimental drinks. The cola flavored soda was provided in 300ml glass bottles. Nothing was done to inform the subject of the identity of the drink (alphamumeric codes were used on the cap or sleeve). Subjects were required to drink four bottles (1,135g) of soda daily.

  • Soda conditions: Subjects were directed to drink four sodas per day, to keep unopened bottles in the refrigerator and record the time each bottle was consumed.

  • No-soda condition: No special instructions for the week. At the end of the weekly visit, subjects were given 28 bottles of soda for the following week.

  • Debriefing and taste tests: End of nine-week test period, taste tests were conducted to see if subjects could recognize differences between soda containing APM and HFCS.

  • Each subject received a series of 16 counter-balanced triangle tests: Subject attempted to pick the disparite soda from the three 10m; samples of soda, two of one variety and one of the other. Second allowed to drink as much as they wanted from four cups of soda. Two glasses contained APM-sweetned soda and two HFCS sweetned soda. Then they were asked wheter the soda was diet or regular. Then asked what the subject thought the study was about. Dietary Records analyzed by nutritionist 3 diet analysis software. Foods not in database were obtained directly from the manufacturer.

Data Collection Summary:
  • Weight: Start of test period and then at weekly intervals, each subject was weighted. The weight was not shared with the subject.
  • Timing of Measurements: Once a week for three weeks.
  • Dependent Variables: Sweetener content of drink.
Description of Actual Data Sample:
  • Initial N: 13 female and 28 male subjects
  • Attrition: One female and five males stopped keeping dietary records or failed to keep appointments in the laboratory. Three females were eliminated because of chicken pox, pneumonia and relocation. Two males complained about having to drink too much soda.
    • Final N: Nine females and 21 males).
  • Age: Females 28.2±2.7 and males 22.9±0.8
  • Anthropometrics: BMI females and males were 25.4±1.4, 25.1±0.5kg/m2, respectively and fall just below the 75th percentile for body weight distribution.
  • Location: University of Pennsylvania.
Summary of Results:

Effect on Dietary Nutrient Intake of Drinking Soda (1,135g per day) Sweetened with APM or HFCS (Mean±SEM)


No Soda (kcal per day) 

APM (kcal per day)

HFCS (kcal per day)

Females (N=9)      



341±53 A

314±43 A, C

Total Intake 2,020±181 1,784±188 B 1,737±141 B, C
Males (N=21)      



453±40 A

461±38 A, C

Total Intake


2,647±153 B

2,645±124 B, C

Other Findings

  • Body Weight: Subjects gained slightly but significantly more weight after two weeks of drinking HFCS-sweetened soda than after the same period drinking APM-sweetened soda or no experimental soda. Difference was more marked after three weeks. Females lost significantly more weight than did males during the control (no soda) period. While drinking HFCS-sweetened soda, females gained weight significantly (0.97±0.25kg, P<0.01) and males gained slightly (0.52±0.23kg, NS). Drinking APM-sweetened soda, females gained weight slightly (0.25±0.29kg, NS), but males lost significantly (0.47±0.22kg, P<0.05).

Food Intake

  • Females consumed significantly less than did males and there was no interaction between sex and treatment.
  • Calories: Relative to calorie intake during the no-soda condition, drinking 530kcal HFCS-sweetened soda per day produced a large and highly significant increase in total calorie intake (including calories in the experimental soda). Drinking the same volume of APM-sweetened soda decreased calorie intake. Both APM and HFCS consumption significantly reduced intake of calories from the diet to the same extent (by 179kcal and 195 kcal per day, respectively). The decrease in dietary calorie intake produced by drinking either form of soda was due entirely to a decrease in sugar intake. Drinking soda did not affect the intake of protein, fat, alcohol or complex carbohydrates.
  • Sugar and soda: During the period without experimental sodas, average intake of sugar-sweetned soda was 292±233g for females and 414±85g for males.
  • Taste tests: Subjects could identify regular, but not diet soda.
Author Conclusion:
  • Drinking large volumes of APM: Sweetened soda, in contrast to drinking HFCS-sweetened soda, reduces sugar intake and thus may facilitate the control of calorie intake and body weight. Drinking APM-sweetened soda decreased the calorie intake of both sexes signifcantly and reduces the body weight of males, but not females, significantly. It remains to be seen whether this finding, using normal-weight subjects given large volumes of APM-sweetened soda for relatively short periods (three weeks), generalizes to other populations, other food products and more prolonged periods of artificial sweetener consumption.


  • Measuring food intake in free-living humans
  • Counterbalanced design, which is that carry-over effects from one treatment to another may occur.
Funding Source:
Reviewer Comments:
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) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
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? Yes
  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? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  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) N/A
  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? N/A
  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? Yes
  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%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? Yes
  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? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? Yes
  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.) Yes
  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? Yes
  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? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? Yes
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
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? Yes
  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? Yes
  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? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
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? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  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)? Yes
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? Yes
  8.6. Was clinical significance as well as statistical significance reported? Yes
  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? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes