BHS107A: Evaluating Ketogenic Diet Effects on Body Composition

This report provides a critical appraisal of an article by Vargas et al. (2018) investigating the impact of a ketogenic diet on the body composition of trained men. The evaluation covers various aspects of the research, including the literature review, aims and hypothesis, methodology (subjects, apparatus, control groups, subject assignment, treatment parameters, and potential biases), and results (tables, graphs, statistical selection, and interpretation). The report assesses the study's internal and external validity, overall quality, strengths, and limitations, offering a comprehensive analysis of the research design and findings concerning ketogenic diets and their effect on body composition in conjunction with resistance training.

Running head: CRITICAL APPRAISAL
CRITICAL APPRAISAL
Name of the Student:
Name of the University:
Author note:

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Table of Contents
1. Introduction......................................................................................................................2
2. Evaluation of Introduction...............................................................................................2
2.1. Literature Review.....................................................................................................2
2.2. Aims and Hypothesis................................................................................................3
3. Evaluation of Methods.....................................................................................................4
3.1. Subjects.....................................................................................................................4
3.2. Apparatus/Instrumentation.......................................................................................5
3.3. Control Groups.........................................................................................................5
3.4. Subject Assignment..................................................................................................5
3.5. Treatment Parameters...............................................................................................6
3.6. Rosenthal and Hawthorne effects.............................................................................6
4. Evaluation of Results.......................................................................................................7
4.1. Tables and Graphs....................................................................................................7
4.2. Selection of Statistics................................................................................................7
4.3. Interpretation of Findings.........................................................................................8
5. Conclusion.......................................................................................................................9
5.1. Internal Validity........................................................................................................9
5.2. External Validity.......................................................................................................9
5.3. Overall Quality.........................................................................................................9

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References..........................................................................................................................10

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1. Introduction
In this paper, the article by Vargas et al. (2018), which explores the effect of ketogenic
diet on the body composition of trained men, will be critically evaluated. With the aid of a
randomized controlled trial, the authors in the given study aimed to extensively explore the
consequences on body composition after engaging in an exercise protocol of resistance training
coupled with energy surplus upon consumption of a ketogenic diet for a period of 8 weeks.
Ketogenic diets, with their characteristic dietary principles of comprising of a negligible amounts
of carbohydrate and high amounts of fat, have been the traditional therapeutic diets of choice for
the treatment of seizures in children suffering from epilepsy. At present, limited evidence
highlights in detail on the true effects of ketogenic diet on altering the body composition among
trained individuals, when coupled with a regimen of resistance training. Hence, gaining insights
on the association between body composition, ketogenic diet and resistance training form the
underlying rationale behind selection of this article (Hall et al., 2016).
2. Evaluation of Introduction
2.1. Literature Review
Upon evaluation of the article by Varagas et al. (2018), it can be observed that an
extensive list of references have been incorporated which includes a large variety of 56
references. Further relevant information from the references have been incorporated throughout
the paper as observed in the authors inclusion of ample in text citations in the background,
methodology, results and most importantly in the major section of the discussion. An extensive
list of references incorporated throughout every section of the paper is a major strength of this

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study, since not only is it indicative of comprehensive research but also cohesiveness associated
with relating and justifying key research concepts with valid, established multifaceted theoretical
perspectives (Hart, 2018). Further, upon evaluating the reference list it can be observed that the
authors have included articles of significant currency, which have been published within the last
decade except for probably one reference paper which was published in 1985. Inclusion of
articles published at relatively recent time span is a major strength since it is indicative of author
inclusion of valid, updated information (Machi & McEvoy, 2016). Though the inclusion of one
article older in terms of publication may be considered a hindrance, the extensive use of recent
literature may compensate for loss in validity incurred. Further, it seems that the authors have
referred to studies which comprise of both qualitative as well as quantitative data - a key strength
indicative of comprehensive research. However, inclusion of greater number of quantitative
studies could have been an added improvement in terms of research validity considering the
possibilities of publication bias in qualitative papers (Booth, Sutton & Papaioannou, 2016).
Despite the use of a comprehensive, valid and updated reference list, lack of inclusion of a
separate section of literature review can be considered as a major limitation since the inclusion of
the same enhances reader understanding. However, a key strength lies in the inclusion of
references relevant to the research title of ketogenic diet and its effects on body composition
hence indicative of authors’ conductance of valid, relevant research (Moher et al. 2015).
2.2. Aims and Hypothesis
Upon extensive reading, it can be observed that the objectives of the paper have been
clearly mentioned in the abstract as well as in the introductory background section, though,
inclusion of a separate section with headings would have improve readability and understanding
of the same. However, the authors have clearly stated the questions hypothesized prior to the

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methodology section, which can be considered as key strength since it allows the reader to easily
identify the focus of the study and research objectives of the author (Elwood, 2017). It can be
further be observed that the questions posed by the author clearly mention the population of
trained individuals undergoing resistance training, an intervention of a hypercaloric ketgenic diet
with outcomes in terms of fat reductions and enhancement of fat free lean mass. Hence, this can
be considered as a key strength in terms of readability and understanding since presence of clear,
detailed research questions enlightens readers on details of the research with ease (Davey et al.,
2015).
3. Evaluation of Methods
3.1. Subjects
The participants for the study comprised of athletes experienced in overload training
which is of relevance to the research objective of exploring dietary effects on resistant training. It
can also be observed that the sample was adequately described in terms of their gender, age,
training experience, anthropometric along with consumption of ergogenic medications. The
selection of participants took place ethically as can be observed in the authors’ provision of a
form of consent as well as obtaining ethical approval from a notable ethics committee (Palinkas
et al., 2015). The participants were also enlightened on the details of the study, coupled with the
risks. While the strengths of this study lie in the ethical selection of participants relevant to the
research objective, it must be noted that a relatively small sample size was selected - key
limitation which may hinder internal validity. Further, appropriate sampling methods of random
yet purposive selection was conducted as per the research objective of exploring training athletes
which is indicative of an avoidance of bias (Malterud, Siersma & Guassora, 2016).

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3.2. Apparatus/Instrumentation
In terms of intervention, it can be observed that the authors utilized dual X-ray
absorptiometry (DEXA) scanner coupled with trained technicians assessing the participants as
well as calibration of the equipment to ensure correct applicability and functioning. Considering
that DEXA scans are appropriate for measuring body composition along with observing author
usage of correct precautionary protocols, this can be considered as a key strength in terms of
relevance. However, except for highlighting the manufacturing details of the equipment, the
authors did not mention any validity or reliability associated with this instrumentation - which
can be considered as key limitation (Smith-Ryan et al., 2017).
3.3. Control Groups
It can be observed in terms of evaluation of the nutritional interventions, a control group
was allocated - a key strength as per standard rules of conducting a randomized controlled trial.
However, a key limitation lies in the authors not mentioning the alternative treatment allocated to
the control group (Thall, Fox & Wathen, 2015). However, details of the groups receiving
ketogenic as well as non-ketogenic diet in terms of macronutrient distribution were clearly
mentioned, which can be considered as a strength in terms of standard randomization protocol.
However, there is a absence of any details of the control group whatsoever in terms of
consistency of usage as well as ethical considerations – which can be understood as major
limitations (Porter et al., 2017).
3.4. Subject Assignment
Upon extensive reading, it can be observed that the participants were allocated randomly
to the treatment groups of ketogenic and non-ketogenic dietary interventions – a key strength in
terms of adherence to the standard protocols of a randomized controlled trial. Upon reading, it is

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also evident, that the details of allocation in terms of dietary interventions and provision of a
hypercaloric and low carbohydrate ketogenic diet have been adequately described - a major
strength in terms of comprehensiveness and understanding for the reader (Rosenberger &
Lachin, 2015). However, changes in allocation and reporting could be observed in terms of 2
participants being excluded for not entering ketogenic states. Such details in mentioning
allocation as well as reporting by the authors’ can be considered as key strengths. However,
considering that ketogenic states are required to achieve the true benefits of a ketogenic diet –
differences in terms of excluding participants will not affect validity of the research (Manikam,
2018).
3.5. Treatment Parameters
It can be observed that the treatments of the prescribed parameters have been adequately
described in terms of dietary principles of a hypercaloric ketogenic diet, assessment of body
composition as well as details of moderate to high exercise loads comprising of push and pull
exercises – a key strength in terms of comprehensiveness and research detail. While there were
no details in terms of the settings of the study – a major limitation - the incorporation of trained
personnel for resistance training and running of DEXA scans were key strengths of this study
(Shea et al., 2017).
3.6. Rosenthal and Hawthorne effects
The authors extensively reported effects of positive effects on body composition in terms
of reduced visceral adipose tissue, body weight and lean body mass. However, there seems to be
an absence of a Hawthorne and Rosenthal effect since the authors addressed these effects in
detail by highlighting that significant changes were not observed due to consumption of a

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ketogenic diet spanning for 8 weeks - which can be considered as a key strength of this trial in
terms of any form of bias in participant results due to researcher influence (El-Saed et al., 2018).
4. Evaluation of Results
4.1. Tables and Graphs
Upon reading the research it can be observed that the tables of the graphs were provided
in detail in terms of characteristics of participants, the results before and after interventions as
well as body composition of participants before and after the dietary interventions. Not only
were the tables observed to contain clear, understandable headings but appropriate abbreviations
as well as full forms of the same were provided at the end of each (Rolfes, Roth & Schnotz,
2018). However, in terms of graphs highlighting body composition changes, despite the usage of
adequate legends, headings and abbreviations of full forms, there seemed to be no clear detailing
of the X axis. Hence, while the usage of detailed tables were a major strength of this study,
incomplete information in the graph affected comprehension and readability (Boers, 2016).
Further, there was no detailed mention of correlations established in the study - a key limitation.
However, the authors’ highlighting effects associated between ketogenic diet administration and
increase in lean body mass, decrease in visceral adipose tissues and body weight can be a
considered as a strength in terms of comprehensive statistical analysis (Roth et al., 2018).
4.2. Selection of Statistics
There was no detailed discussion of population data distribution except for mentioning
that Shapiro-Wilk test was used to determine Gaussian distribution of data. The authors however
clearly mentioned that descriptive statistics were used with however no detailed mentioning of
compliance with population distribution. However, there was no outlining of data analysis using

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univariate, multivariate and repeated measures general linear model – which is indicative of a
discussion differences in effect size in terms of treatments administered (Gignac & Szodorai,
2016). Indeed in terms of effect sizes, the authors provided a detailed discussion in terms of a
medium effect on fat mass and a large effect on visceral adipose tissue upon ketogenic diet
administration - a key strength (Bosco et al., 2015). A confidence interval of 95% was used
signifying that with 95% confidence it can be said that there is a significant relation between
ketogenic diets, body weight, fat and lean body mass (Bonett & Wright, 2015).
4.3. Interpretation of Findings
Changes in visceral adipose tissue, body weight, and lean body mass and fat mass were
the outcomes mentioned clearly by the authors. As evident from the reading, the findings of the
trial were relevant with the results where the authors noted positive body composition changes
after ketogenic diet consumption while also noting that lean body mass may not be affected
significantly during positive energy balance. It was also observed that the authors mentioned no
inappropriate generalizations by noting that this diet-exercise intervention may not be adequate
for lean body mass reductions due to insignificant effects (Vargas et al., 2018). Despite paving
the way for considering novel diet and exercise recommendations for body mass interventions,
the benefits may not outweigh the statistical significance considering the small sample size,
inclusion of only men, lack of blood tests, considering of appetite suppressing effects of
ketogenic diet and lack of information on effects upon a population with high fat mass (Heale &
Twycross, 2015).

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5. Conclusion
5.1. Internal Validity
The inclusion of a small sample size, consisting of only men who are trained may hinder
internal validity in terms of hindering statistical powering, generalization and applicability of the
study in uncontrolled settings and increase susceptibilities of type II statistical error (Andrade,
2018).
5.2. External Validity
The external validity may be hindered in terms of effects on body composition
considering that the characteristic appetite suppressing nature of a ketogenic diet were not
evaluated. Further, lack of blood testing as well as inclusion of women or individuals with high
fat mass hinder the generalization and applicability of the study (Vargas et al., 2018).
5.3. Overall Quality
A key strength of the study lies in its adequate usage of randomization, extensive
researches and detailed statistical analysis paving the way for novel ways for athletes to regulate
body composition using a ketogenic diet and resistance training (Vargas et al., 2018). However,
inadequate internal and external validity in terms of small sample size, lack of consideration of
blood tests and appetite suppressing effects of the ketogenic diet and inclusion on only men with
a small size, are key weaknesses hence calling for conductance of more robust research with a
sample of varied demographics (Huebschmann, Leavitt & Glasgow, 2019).

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