8 e-Letters

  • The 3500 Kcal Rule is Invalid for Projections of Weight Change

    Nyenwe et al. (1) address an interesting and important topic of the effects or associations of parental diabetes with offspring outcomes. However, the paper contains an important error that renders one of their conclusions markedly incorrect.

    Specifically, having estimated a difference in energy expenditure among offspring of parents with diabetes (which the authors refer to as ‘parental diabetes’) versus offspring of parents without diabetes, the authors project that persons with parental diabetes will, as a result of this difference, steadily gain substantial weight indefinitely. They state:

    “According to the data published by Wishnofsky (2), one pound has a caloric value of 3500 kcal or (1 kg=7700 kcal). We derived the estimated weight gain in kg by dividing the projected energy accrual by 7700. When normalized REE is used for this estimation, subjects with parental diabetes had a daily energy surplus of 125 kcal which would translate to ~6 kg weight gain per year.”

    This type of estimation is commonly referred to as the 3500 kcal rule or 3500 kcal per pound rule.

    This reasoning and calculation is erroneous because it fails to account for the dynamic changes of energy expenditure that occur with weight gain and loss. Wishnofsky himself noted the complexity of estimating energetic equivalents of gaining or losing body weight, specifically addressing the importance of time, nitrogen balance, tissue type, and water loss, among other factors, on...

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  • Estrogens and other uncovered associations with diabetes and cardiovascular diseases among female workers

    To the Editor

    We read with great interest the article by Gilbert-Ouimet M et al1 recently published in your journal. Such study showed an interesting result that only increased risk of incidence of diabetes occurring among female workers working 45 hours or more per week, and suggested that modification of such risk factors would be helpful to improve prevention strategies and orient policymaking by following up 7065 workers over a 12-year period in Ontario, Canada.
    However, we have some concerns. Firstly, in order to find out the potential relationship between long work hours and the incidence of diabetes, several other independent variables were considered in the analysis process such as sociodemographic and health-related covariates, but the information of menopause and menopausal hormone therapy (MHT) among women was not added. Strong association with increased risk of cardiovascular diseases had been confirmed in several studies and data from large randomized-controlled trials have shown that the decrease of incidence of T2D in women could be achieved by MHT with conjugated estrogens 2,3 . Although the clinical evidence still not be sufficient to recommend the use of hormones for prevention of diabetes among women especially with early menopause or premature ovarian insufficiency4, such detail might be helpful to uncover the neglected association between menopause and increased risk of diabetes.
    Secondly, compared with the increased risk...

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  • The hot environment hypothesis in diabetes pathophysiology

    Dear editor,

    The study published in a recent volume of the journal by Blauw et al. is an excellent opportunity to highlight an under-examined environmental hypothesis in the pathophysiology of type 2 diabetes.1 In their epidemiological study, the authors used meta-regression models and demonstrated that diabetes incidence rate in the USA has increased with higher outdoor temperatures from 1996 and 2009, after adjustment for most common confounders. They also evidenced an independent association between the prevalence of glucose intolerance worldwide and mean annual temperature on a global scale. The theoretical background for the work mainly stands on the reduction in brown adipose tissue activity due to high ambient temperature that is expected to negatively impact glucose metabolism. This view is plausible, particularly since recent data uncovered potential crosstalk between brown adipose tissue and glucose regulatory pathways,2 but it is important for us to discuss the context of the study.

    We are definitely concerned about the burden of consequences of climate change including biodiversity assault, threats to the human species’ safety, health and well-being because of increased risks related to extreme weather events, wildfire, air quality, and other environmental disease carriers. However, isn’t it cynical that the glucose metabolism disturbance observed in warm environmental temperature might become a serious working hypothesis concomitantly with (b...

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  • Methodological considerations of a systematic review and meta-analysis: dietary carbohydrate restriction in patients with type 2 diabetes

    Thank you to the authors for addressing a relevant and interesting area of research (Snorgaard et al., 2017).

    The review was well planned, but the methodology lacks detail that enables the reader to understand the processes involved in the completion of the meta-analysis and some study limitations were not described.

    Please could the authors clarify why the meta-analyses use both mean change from baseline and mean final value in the same meta-analysis (see Figure 2 and Figure 3 where the lower means indicate change from baseline and the higher means indicate unadjusted final values)? Also, could it be clarified why the selected arms from the three-arm trials were chosen over the arms that were omitted? Although the population, intervention and outcomes were defined in the methodology, the comparator was not.

    Furthermore, when using the mean final HbA1c value in the meta-analyses, papers such as Krebs et al. (2012) and Guldbrand et al. (2012) have higher baseline HbA1cs in the lower-carbohydrate group, which was not mentioned in the paper, nor mentioned as a limitation to the meta-analysis. Guldbrand et al. (2012) demonstrate that HbA1c remained the same at two years (the time point the authors refer to) in the lower-carbohydrate arm but increased in the comparator arm by 0.2%. Therefore the low-carbohydrate arm was the superior intervention; however, the forest plot (Figure 3) suggests that the control intervention was slightly but not significant...

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  • Re:The genes associated with a high risk of type 1 diabetes are becoming less common
    Wen-Peng You
    We thank colleagues for their critical comments that help to clarify relationships we have studied. We are not concerned with the frequency of what specific genes, high-risk or not, has increased recently. We are just making a general statement that with relaxed natural selection detrimental mutations may accumulate. The paper by Witas et al. cited by our critics uses the same rationale as we do when suggesting changes in type 1 d...
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  • The genes associated with a high risk of type 1 diabetes are becoming less common
    Sarah G Howard
    In the article, "Type 1 diabetes prevalence increasing globally and regionally: The role of natural selection and life expectancy at birth" (You and Henneberg 2016), the authors find a correlation between worldwide type 1 diabetes prevalence and both life expectancy at birth and the "Biological State Index" (Ibs), a measure of population reproductive success. Based on these findings, they argue that "the correlation of Ibs to the...
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  • Re:Nutty conclusion in walnut study
    Valentine Y. Njike

    We appreciate the attention to our manuscript[1].

    We will start by emphasizing that we cannot control what has been written in the media about this study. We will therefore limit our response to the reviewer's comments that directly pertain to our manuscript.

    The results of this study are clearly enumerated in the paper, with the supporting data shown in every instance[1]. We distinguish explicitly be...

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  • Nutty conclusion in walnut study
    Stephen L. Black

    Nutty conclusion in walnut study

    This study purports to show that eating walnuts lowers cholesterol level, a claim enthusiastically and uncritically repeated in the media (e.g."A handful of walnuts a day may help lower cholesterol:study", CTV News, November 25, 2015). Unfortunately, the claim is spurious, as the published data show no such effect.

    The study is well-controlled in including a randomized control group...

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