- Email: [email protected]
Questions Regarding Weighing Every Day
PRACTICE APPLICATIONS Letters to the Editor Questions Regarding Weighing Every Day To the Editor: In the article “Weighing Every Day Matters: Daily Weighing Improves Weight Loss and Adoption of Weight Control Behaviors,”1 the authors conclude that “weighing every day led to greater adoption of weight control behaviors and produced greater weight loss compared with weighing most days of the week.” It is surprising that the authors’ use of causal language passed rigorous editorial review of the Journal for a number of reasons. First, the study design and data presented in the authors’ analysis do not allow for causal inference. We cannot access the directionality of the association between daily weighing and weight loss; it remains unknown whether or not people who weigh themselves each day are more motivated to lose weight, and therefore are more likely to weigh themselves more frequently due to their motivation, or whether the frequent weighing itself sparks behavior change in the individual. Second, these data are confounded by 1) priming by the questionnaire at baseline and 6 months, 2) dissimilar feedback provided to daily vs nondaily weighers in the intervention, and 3) the multiple moving parts of the 6month intervention given as a whole. How can we truly know that it was the weighing frequency, and not one of the many other factors employed in the original study design, that accounted for between-group differences? There was no effect-size or power calculation provided to evaluate this.
LETTERS TO THE EDITOR ARE WELCOME Letters to the Editor may be submitted at http://ees.elsevier.com/andjrnl for consideration regarding manuscripts published within the past 6 months. Letters should be no more than 500 words, can contain up to 20 references, and should include a funding disclosure, conflict of interest disclosure, and copyright/authorship form. All letters will be subjected to editorial review and decision before acceptance.
ª 2016 by the Academy of Nutrition and Dietetics.
Third, eligibility criteria in the original study required that participants not have recent weight loss; however, multiple individuals reported daily weighing at baseline. If truly interested in whether daily weighing led to greater adoption of weight control and produced weight loss, why weren’t these original “daily weighers” excluded? Finally, as mentioned in the limitations, no multiple comparisons testing was done to look at experiment-wise differences between groups. I calculated a simple Bonferroni-corrected P value (0.05O37 Weight Management Strategies Questionnaire questions ¼ 0.001). Of the data presented, only one question obtains this level of significance. Along this same line, only betweengroup comparisons at 6 months were presented; however, many of the behaviors such as “increased steps” or “reduced caloric intake by 500-1,000 kcal/d” may not have been applicable after 6 months of an in-depth intervention. One cannot increase daily steps forever. Eligibility criteria included individuals with body mass indexes of 24 to 60; would we expect a participant with a body mass index of 24 at baseline to continue to reduce their caloric intake by 500 kcal/d after 6 months? A withingroup comparison would have been a simple way to provide this information. Overall, this article added very little to our understanding of what frequency of self-weighing should be recommended for weight control. In the Results section, the authors state “there were no differences by self-weighing frequency in dietary strategies, calorie intake, or calorie expenditure.” What message must we be sending as practitioners, then, if our bottom line is that daily weighing with no change in caloric intake or expenditure is an effective way to lose weight? Lua Wilkinson, MA, RD, CDN Doctoral Candidate, Human Nutrition Cornell University Ithaca, NY
Statement of Potential Conflict of Interest: No potential conflict of interest was reported by the author. Funding/Support: There is no funding for this letter.
Reference 1.
Steinberg DM, Bennett GG, Askew S, Tate DF. Weighing every day matters: Daily weighing improves weight loss and adoption of weight control behaviors. J Acad Nutr Diet. 2015;115(4):511-518.
http://dx.doi.org/10.1016/j.jand.2015.11.006
Author’s Response: We are writing to respond to Ms Wilkinson’s letter regarding our published manuscript, “Weighing Every Day Matters: Daily Weighing Improves Weight Loss and Adoption of Weight Control Behaviors.”1 We appreciate Wilkinson’s suggestions for possible drivers of the finding that daily weighing improved weight loss and adoption of weight-control behaviors as compared to weighing 5 days per week. In general, it is important that the findings from this current manuscript be interpreted alongside the main outcomes paper published in Obesity in 2013.2 Indeed, we were surprised by the magnitude of the original effect in the parent study. We found that a daily weighing intervention that included weekly e-mailed feedback and lessons produced 6% weight loss at 6 months as compared with a delayed control group who lost nothing. Moreover, adherence to daily weighing was strong—on average intervention participants weighed 6 days per week over the 6-month period. These results are clearly within the range of clinical meaning and indicate a positive response to daily weighing. As such, we conducted a follow-up study to probe possible correlates of this intriguing finding, with the goal of informing the growing research in daily weighing. Counter to Wilkinson’s suggestion, we did not infer a causal association between self-weighing frequency and weight loss. Indeed, we were careful to suggest that future studies need to empirically manipulate self-weighing frequency to determine whether causal relations exist. However, our findings are supported by secondary analyses of Linde and colleagues,3 Gokee-LaRose and colleagues,4 and Van Wormer and colleagues,5 and dovetail with our suggestion that daily weighing may be the optimal self-weighing frequency. Like
JOURNAL OF THE ACADEMY OF NUTRITION AND DIETETICS
405
LETTERS TO THE EDITOR ARE WELCOME Letters to the Editor may be submitted at http://ees.elsevier.com/andjrnl for consideration regarding manuscripts published within the past 6 months. Letters should be no more than 500 words, can contain up to 20 references, and should include a funding disclosure, conflict of interest disclosure, and copyright/authorship form. All letters will be subjected to editorial review and decision before acceptance.
ª 2016 by the Academy of Nutrition and Dietetics.
Third, eligibility criteria in the original study required that participants not have recent weight loss; however, multiple individuals reported daily weighing at baseline. If truly interested in whether daily weighing led to greater adoption of weight control and produced weight loss, why weren’t these original “daily weighers” excluded? Finally, as mentioned in the limitations, no multiple comparisons testing was done to look at experiment-wise differences between groups. I calculated a simple Bonferroni-corrected P value (0.05O37 Weight Management Strategies Questionnaire questions ¼ 0.001). Of the data presented, only one question obtains this level of significance. Along this same line, only betweengroup comparisons at 6 months were presented; however, many of the behaviors such as “increased steps” or “reduced caloric intake by 500-1,000 kcal/d” may not have been applicable after 6 months of an in-depth intervention. One cannot increase daily steps forever. Eligibility criteria included individuals with body mass indexes of 24 to 60; would we expect a participant with a body mass index of 24 at baseline to continue to reduce their caloric intake by 500 kcal/d after 6 months? A withingroup comparison would have been a simple way to provide this information. Overall, this article added very little to our understanding of what frequency of self-weighing should be recommended for weight control. In the Results section, the authors state “there were no differences by self-weighing frequency in dietary strategies, calorie intake, or calorie expenditure.” What message must we be sending as practitioners, then, if our bottom line is that daily weighing with no change in caloric intake or expenditure is an effective way to lose weight? Lua Wilkinson, MA, RD, CDN Doctoral Candidate, Human Nutrition Cornell University Ithaca, NY
Statement of Potential Conflict of Interest: No potential conflict of interest was reported by the author. Funding/Support: There is no funding for this letter.
Reference 1.
Steinberg DM, Bennett GG, Askew S, Tate DF. Weighing every day matters: Daily weighing improves weight loss and adoption of weight control behaviors. J Acad Nutr Diet. 2015;115(4):511-518.
http://dx.doi.org/10.1016/j.jand.2015.11.006
Author’s Response: We are writing to respond to Ms Wilkinson’s letter regarding our published manuscript, “Weighing Every Day Matters: Daily Weighing Improves Weight Loss and Adoption of Weight Control Behaviors.”1 We appreciate Wilkinson’s suggestions for possible drivers of the finding that daily weighing improved weight loss and adoption of weight-control behaviors as compared to weighing 5 days per week. In general, it is important that the findings from this current manuscript be interpreted alongside the main outcomes paper published in Obesity in 2013.2 Indeed, we were surprised by the magnitude of the original effect in the parent study. We found that a daily weighing intervention that included weekly e-mailed feedback and lessons produced 6% weight loss at 6 months as compared with a delayed control group who lost nothing. Moreover, adherence to daily weighing was strong—on average intervention participants weighed 6 days per week over the 6-month period. These results are clearly within the range of clinical meaning and indicate a positive response to daily weighing. As such, we conducted a follow-up study to probe possible correlates of this intriguing finding, with the goal of informing the growing research in daily weighing. Counter to Wilkinson’s suggestion, we did not infer a causal association between self-weighing frequency and weight loss. Indeed, we were careful to suggest that future studies need to empirically manipulate self-weighing frequency to determine whether causal relations exist. However, our findings are supported by secondary analyses of Linde and colleagues,3 Gokee-LaRose and colleagues,4 and Van Wormer and colleagues,5 and dovetail with our suggestion that daily weighing may be the optimal self-weighing frequency. Like
JOURNAL OF THE ACADEMY OF NUTRITION AND DIETETICS
405