EAL

NNNS: Weight (2006)

Citation:

Study Design:

Class:

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Quality Rating:

Research Purpose:

Attempted to sketch out a conceptual background, against which they could describe in a series of studies that they conducted on the spontaneous food intakes of non-obese and obese subjects, following caloric dilution of their diets with aspartame.
To determine whether people would defend their habitual level of energy intake in response to covert caloric dilution of their diet.

Inclusion Criteria:

None.

Exclusion Criteria:

None.

Description of Study Protocol:

Review of papers to test body weight hypothesis with aspartame.

Data Collection Summary:

Description of Actual Data Sample:

Summary of Results:

Poirikos et al, 1977: 15-day experiment involving six obese women and two obese men, who were 24% to 134% overweight. They received a sucrose-containing diet on Days One to Three and Days 10 to 15. The energy-diluted diet, which contained aspartame-sweetened items substituted for sucrose, was fed on Days Four to Nine. The data showed that the use of low-calorie analogs decreased total energy intake by 14%. The subjects' increased energy intake during the second half of the aspartame-substitution period emphasized the need for a longer-term study.
Porikos et al, 1982: 24 days of six men with normal body weight. The study design was the same as the first study, but the initial baseline period and the aspartame periods were doubled in length (six days baseline, 12 days aspartame-substitution and a final six days of baseline). When the aspartame-sweetened analogs of sucrose-containing foods were substituted for those foods, there was a significant decrease in energy intake.
Porikos, Pi-Sunyer, 1984: Observed responses of five obese people over a 12-day caloric dilution period and compared them to responses of eight normal-weight subjects. Non-obese subjects were within 10% of desirable body weight and the five obese men were 18-45% overweight. Design was the same as the second study, but there was an additional six days of baseline at the end of the study to provide a total duration of 30 days. Both obese and non-obese subjects showed a significant decrease in energy intake on the aspartame diet.

Author Conclusion:

The data suggests that even under conditions where energy output remains relatively constant, people do not regulate their energy intake precisely. When the caloric density of a palatable and conventional diet was covertly substituted with an artificial sweetener for sucrose, the subjects stabilized their intake at 85% of baseline. Short-term, there was no physiological drive to replace completely all calories diluted out of the experimental baseline diet.
Therefore, longer studies with covert substitution of low-calorie analogs are needed.

Funding Source:

Reviewer Comments:

Reviewed mainly three articles by Porikos.
Lacked comparison to other studies.
Weight data not reported, mainly reported energy intake effects.

Quality Criteria Checklist: Review Articles
Relevance Questions
	1.	Will the answer if true, have a direct bearing on the health of patients?	Yes
	2.	Is the outcome or topic something that patients/clients/population groups would care about?	Yes
	3.	Is the problem addressed in the review one that is relevant to dietetics practice?	Yes
	4.	Will the information, if true, require a change in practice?	Yes

Validity Questions
	1.	Was the question for the review clearly focused and appropriate?	Yes
	2.	Was the search strategy used to locate relevant studies comprehensive? Were the databases searched and the search termsused described?	No
	3.	Were explicit methods used to select studies to include in the review? Were inclusion/exclusion criteria specified andappropriate? Wereselectionmethods unbiased?	No
	4.	Was there an appraisal of the quality and validity of studies included in the review? Were appraisal methodsspecified,appropriate, andreproducible?	No
	5.	Were specific treatments/interventions/exposures described? Were treatments similar enough to be combined?	Yes
	6.	Was the outcome of interest clearly indicated? Were other potential harms and benefits considered?	Yes
	7.	Were processes for data abstraction, synthesis, and analysis described? Were they applied consistently acrossstudies and groups? Was thereappropriate use of qualitative and/or quantitative synthesis? Was variation in findings among studies analyzed? Were heterogeneity issued considered? If data from studies were aggregated for meta-analysis, was the procedure described?	No
	8.	Are the results clearly presented in narrative and/or quantitative terms? If summary statistics are used, are levels ofsignificance and/or confidence intervals included?	No
	9.	Are conclusions supported by results with biases and limitations taken into consideration? Are limitations ofthe review identified anddiscussed?	No
	10.	Was bias due to the review's funding or sponsorship unlikely?	Yes