Research Question
Does the level of proteins in a diet determine energy expenditure, weight gain, and body composition?
Purpose of the Study
The major purpose of the study is explanatory. Explanatory research aims at supporting previous hypotheses concerning a given issue with the view of explaining cause and effect relationships. In this case, the study explains Stock’s hypothesis that metabolic efficiency occurs when an individual overeats diet with normal protein level, while metabolic inefficiency occurs when an individual overeats diet with low and high protein levels (Bray et al. 48). Moreover, this study explains the relationships that exist between dietary protein level and energy expenditure, weight gain, and body composition.
Variables
Dietary protein level is an independent variable in the study. The dietary protein level is a variable because the theoretical framework holds that different dietary protein levels determine the metabolic efficiency of a person during overeating. The variable exists in three dimensions, namely, low, normal, and high levels of dietary proteins. Metabolic efficiency is a dependent variable. The theoretical basis is that low and high dietary levels of proteins reduce metabolic efficiency, while the normal dietary level of proteins increases metabolic efficiency. In this case, energy expenditure, weight gain, and body composition are the three dimensions of metabolic efficiency.
Study Population
The study population comprised of male and female inpatients admitted in the metabolic unit in Louisiana. Out of the 83 potential participants, the study sampled 28 participants, but 25 participants (males = 16 and females = 9) managed to undergo through the process of research. Thus, the study randomized 25 participants into three groups, namely, low, normal, and high protein diet groups.
Generazability
The findings of the study have a high external validity because of the sample used and research design employed. The study sampled 25 participants, which is a sufficient number of participants to enhance generalization of the findings. Moreover, the study randomized participants into three study groups, thus eliminating selection bias. Regarding research design, the study employed randomized controlled trial and single blind strategy in establishing the impact of different levels of dietary proteins on the participants.
Study Design
The research design that the study employed is randomized controlled trial. The research design is appropriate because the study is a clinical trial that seeks to compare the effects of different levels of dietary proteins on energy expenditure, weight gain, and body composition. Therefore, randomized control trial is the best choice of research design that the study employed.
Data Collection
The study collected data from the participants by measuring energy expenditure and weight gain using ventilated system hood and doubly labeled water respectively. Additionally, the study employed x-ray absorptiometry to measure body composition. The advantage of these methods of measurements is the accuracy, while the disadvantages are that they are complex, cumbersome, and require sophisticated instruments. In the measurement of weight gain, use of weighing machine could have been appropriate.
Ethical Aspect
The study conducted the research in an ethical manner by allowing participants to volunteer, sign an informed consent, and receive compensation. The institutional review board of the Pennington Biomedical Research Center approved the advertisement that the study placed in the newspaper to recruit volunteers. Moreover, the study granted informed consent to all participants. After undergoing through the clinical trials, the participants received compensation from the study basing on their stay in the metabolic unit.
Major Finding
The major finding of the study is that the amount of calories take a person takes during overeating determines weight gain. According to Bray et al., low level of dietary protein allows the storage of 90% of the excess energy as fat, and thus contributes to weight gain (54). Hence, the finding explains why low level of dietary proteins reduces metabolic efficiency.
My Reaction
Since obesity is a nutritional issue, the study explains how the level of dietary proteins influences energy expenditure, weight gain, and body composition. In this view, nutritionists need to consider using dietary protein level in helping people to manage their body weight.
Works Cited
Bray, George, Steven Smith, Lilian Jonge, Hui Xie, Jennifer Rood, Corby Martin, Marlene Most, Courtney Brocks, Susan Mancuso, and Leanne Redman. “Effect of Dietary Protein Content on Weight Gain, Energy Expenditure, and Body Composition during Overeating: A Randomized Controlled Trial.” Journal of the American Academy of Dietitians 307.1 (2012): 47-55. Web.