Question 3
All of the participants in the Schroeder et al. study had to
stay within 5% of their starting weight so that weight loss or weight gain
would not skew the results. Their intake would be adjusted accordingly if they
were not maintaining their weight. If the participants’ weight was not
controlled, do you think the results would be any different? If so, how?
posted by Unknown @ 10:22 AM
12 comments
12 Comments:
If the study hadn't been controlled for weight, I wonder if we would also see weight loss in the traditional Korean diets group. All of the participants in the study were overweight and obese adults. So it could be very possible that having switched their diet so dramatically, they could have also seen a weight loss. I thought it was smart that they controlled the weight though, because it probably made it easier for the researchers to focus primarily on the cardiovascular risk factors instead of having other factors that may have skewed the results.
If participants' weight was not controlled, I can imagine weight loss contributing to decrease in heart disease risk factors since obesity contributes to heart disease. The researchers' plan to keep weight consistent made it easier to attribute any differences between the groups to their diet rather than weight loss and other lifestyle changes. If they did not control for weight, the results would be different in the way that the researchers cannot conclude what the differences in risk factors could be due to - for instance, low sodium diet or weight loss? It also comes to my mind how some participants may have disliked their provided meals/diet but had to force themselves to eat the given amount and may have dropped out from the study. I wonder how successful they were in ensuring participants did not eat anything else but what they were provided.
The results would depend on the food preferences of the participant. If an individual likes a food type, they generally eat more of it, potentially leading to weight gain. If it is something they don’t really like or are not familiar with, they will likely eat less; in which case they could lose weight. Portion control is a huge problem with the Obesity epidemic in America. To truly test the concept, weight had to be controlled. Weight, as mentioned in the article, and as we have learned through our studies, has a very significant impact on chronic disease risk and severity. Participants were selected for BMI > 25 (not a perfect indicator), which could already indicate increased likelihood for imbalance in energy intake versus needs either currently or at some previous point in life. If major changes in weight occurred, the conclusions we are able to draw at this point would be even weaker, and likely confounded. Positive effects of a diet could be masked by gains; negative effects of a diet could be masked by a loss. Conducting experiments with less control, i.e. how things would actually happen in real life, is far down the road from what this study was trying to accomplish.
I think if the researchers had not controlled the participants' weight so closely, it would make the results less valid. As we know, weight loss can be a prevention factor for heart disease and if a participant also lost weight on the diet, the researchers would not for sure know that the results were from the diet and not the weight loss. I agree with Amanda that it eliminates another factor that the researchers would have to consider to avoid having skewed results at the end of the study.
I think by controlling for weight loss the researchers were able to examine the cardiovascular risk factors exclusively. While weight was not examined in this study I believe it would be a good idea to not adjust the diet during a repetition of the study to see the affects the diet has on weight. If the traditional Korean diet also promoted weight loss that can be something to further analyze.
I think that if weight was not controlled in this study the participants would have most likely experienced some weight loss. The Korean diet is more plant based and less processed than the typical American diet. The sodium content of the typical Korean diet is also low compared to the American diet therefore participants would probably experience some weight loss cutting some of those elements out of their diet. I believe another study should be done to determine if the Korean diet can promote weight loss, but I agree with the others that have stated above that controlling weight loss in this particular study was crucial for the success and reliability of the study.
I agree with Amanda that since the participants were all either overweight or obese weight loss would of been more than likely due to a drastic change in diet.
I would imagine that if the weight of the participants was not controlled then any weight loss (related to the prescribed diet or not) would have resulted in more favorable metabolic markers...thereby skewing the results. I think that controlling for weight was one good way that researchers protected the validity of the study. Example: If weight was not controlled, and for some reason participants decided to significantly increase their physical activity during the study to lose weight, then the metabolic data would be useless in determining if the various diets had any effect on the participant's physiological health.
Establishing correlations vs. causality in research settings is already so difficult. Controlling for significant weight change was one way that causality was further suggested between the intervention diets and research results.
I feel that controlling weight was definitely one of the most important aspects to control within this particular study and play a vital role in more accurately determining results. Had the participants been able to have more flexible levels of food intake I think that we would have definitely see more significant differences between each diet for cardiovascular markers. As Amanda and others have mentioned, cardiovascular risk factors were the primary target of the research study therefore controlling for potential variables that could effect this was extremely important.
Thinking of the typical American diet, it is generally much easier to gain weight if not controlled properly because of the much higher fat and calorie content of the foods that are included. Conversely, the participants may have found it to be much easier to lose weight on the DGA diet especially if they had not been exposed to such healthy eating habits previously. The more nutrient dense and lower calorie foods may have created a more ideal environment for weight loss if it had been allowed.
I certainly believe that the results would be different if weight was not controlled. Participants were provided with the foods and portions they could eat, so I believe that overeating would not have posed a major issue. However, if individuals consistently consumed smaller portions based on appetite or taste preference, subjects may have experienced weight loss. Vivian brings up the point that immediately crossed my mind - weight loss would impact the physiological risk factors related to CVD. Therefore, results may seem skewed towards one dietary pattern being "better" in regards to CVD risk.
The study did not focus on weight loss as one of its primary outcomes, therefore weight had to be controlled to isolate the other variables in the study. I also appreciated Desiray's insight on controlling weight in relation to physical activity. If the researchers wanted to study physiological changes based on diet alone, then weight and physical activity needed to remain constant and controlled.
I thought Vivian made a good point in saying that eliminating weight loss as a factor made it easier to attribute differences between the groups to their diet and not the weight loss. As we know, overweight and obesity are related to a number of diseases, especially cardiovascular diseases. Therefore if there would have been a weight loss, how would we know whether it was because the person had lost weight or because they changed the foods in their diet? I think it would also be interesting to do another study where weight was not controlled. I would be curious to see if people adhering to the diet would also dramatically lose weight. I would also be interested in seeing if the fermented foods also help with the microbiome of participants. Desiray makes a good point in saying that correlation vs. causation is important to understand. We very rarely can attribute anything as having a causative effect and must therefore refer to it as simply a correlation. This was something important to keep in the back of the mind when looking at the results of this study.
Des brings up a great point about the already difficult task of distinguishing causality and correlation. It would be more life like to have less controls, but then we would have no idea what precisely was contributing to the changes. Part of the getting the whole picture about a researched concept is looking at it from all angles. We need to view the whole spectrum, from highly controlled to loosely controlled to be able to effectively draw conclusions. Effects of anything and everything we do with our diets are relative to the precise combination of variables in that situation. Where were all of these great ideas for additional studies when we were in Research Methods?
I still like the idea of thinking of a Korean style diet as another potential tool in the toolbox for those with cardiovascular concerns. It might work for some and not work for others, but there would be no harm in offering it as an option IF we do eventually conclude it is effective.
Carly mentions an interesting idea about further studies on the traditional Korean diet on weight loss for obese participants. It would be valuable to see if this plant-based diet with plenty of fermented foods can promote weight loss when participants' portions are not controlled and are allowed to have major weight changes. Determining if weight loss can be a benefit of following a traditional Korean diet could be useful for cardiac patients as well since encouraging weight loss can decrease their risks.
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