An article about a dietary plan to help people lose weight has been retracted after other researchers raised concerns, and the authors failed to provide the data that supported their findings.
The retraction is accompanied by a Letter to the Editor by a group of outside researchers — including David Allison at the University of Alabama at Birmingham — who noticed “several substantial issues with data and calculations.” For instance, before the experiment even started, the two groups had very different weights: The control group averaged 96.5 kg, and the test group 91 kg. According to the letter, that difference is striking:
The distribution of baseline weight was significantly different between groups (p-value = “0.00”)… It is extraordinarily unlikely that any variable would be that different between two groups if allocation was truly random.
The study, published in the Journal of Paramedical Sciences, followed 116 overweight people over 40 days, half of whom were randomly assigned to a test group that received nutrition counseling and healthier food options. The authors, based in Iran, found that people receiving the dietary intervention lost weight, while those in the control group gained:
The results showed that BMI in test group decreased from 27.5 ± 2.36 to 26.8 ± 2.15 (p<0.05), while in control group increased by 0.5 Kg/m2 .
Allison and his co-authors extrapolated the heights of the participants from the BMI and weight data, and found something strange:
We calculated the baseline control group geometric mean as 2.04 cm taller than the test group. These calculations also suggest the control group shrunk by 1.26 cm while the test group grew by 1.52 cm over the study. Neither change is explained by rounding error nor seems plausible for adult subjects over 40 days.
When the original authors wouldn’t provide the data to back up their conclusions, the journal retracted it, according to the retraction note, tucked away at the end of the PDF of the article:
Due to lack of author cooperation to provide the data used in the text “The effect of food service system modifications on staff body mass index in an industrial organization”, the article is retracted.
Additionally, as the letter explains, the number of participants who dropped out changes throughout the paper:
The results section describes an initial sample size of 116 with 14 dropping out (p. 115). The tables report the remaining sample size to be 102, but the body of the text reports 101 subjects remained until study completion.
The journal is not indexed in Thomson Scientific’s Web of Knowledge.
We have reached out to the corresponding author of the paper, Mostafa Mirghotbi at the Shahid Beheshti University of Medical Sciences in Iran, and to the journal. We’ll update this post if we hear back.
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