Researchers from the University of Exeter have been running experiments to determine if exercise reduces chocolate cravings. After asking a selection of regular chocolate eaters to abstain from chocolate for a period of three days, the subjects either sat in a passive environment or went for a brisk walk for fifteen minutes. They were then asked to perform craving-inducing tasks such as mental challenges or opening a chocolate bar. Researchers found that those subjects who participated in physical activity had lower cravings than those who remained in a passive environment for at least ten minutes following the activity.
1) The most prominent claim the news article makes about the study is that a fifteen minute brisk walk reduces chocolate cravings for the duration of the walk and for at least ten minutes afterwards. This claim is supported in the original paper as the discussion section references previous research which has found that exercise suppresses appetite and reduces urges to snack. The news article also claims that chocolate "has a number of biologically active constituents that temporarily enhance our wood with a result that eating it can become a habit, particularly when we are under stress and when it is readily available, and perhaps when we are least active." The original paper addresses this issue briefly but only to acknowledge that exercise may interact with the neuro-pharmacology of choclate and urges (namely the release of dopamine as a reward during "self-administered addictive behaviors") but they have not done enough research to make that claim.
2) The main conclusion of this study as discussed in the conclusions section of the original article states that even a brief amount of physical activity can reduce chocolate cravings, even when presented with a trigger. The news article from Science Daily makes the same claim, directly quoting Professor Adrian Taylor, one of the researchers at the University of Exeter.
3) The discussion section of this paper stresses that additional research is required before sound conclusions can be made. Although the research they have done so far suggests that exercise reduces cravings, the researchers would still like to run more thorough experiments on the subject. While the paper does not necessarily say the scientists are not confident in their discoveries, it mentions that further tests with a larger sample size, and/or testing the effects of higher-intensity exercise, would be ideal. Additional tests in which the stressor is modified would also add to the validity of the research. Although the discussion section of the paper was comparatively lengthy, and discussed other possible tests that would expand their current research, there was no mention of any uncertainties or plans to run further tests in the news article.
4) From the beginning, the news reporter linked this article to previous research which found that exercise may help reduce drug and nicotine cravings. This does not directly follow the findings of the original paper but rather builds upon an idea from the discussion section. One topic the researchers wanted to do further tests on was with neurobiological mediators and the possibility that exercise was involving neurotransmitters and releasing dopamine, similar to the "self-rewarding" effects of eating craved foods. Therefore it follows that the dopamine released during exercise could take the place of dopamine released after assuaging drug or nicotine cravings, but the assertion the news reporter has made does not follow the actual research done for this paper. The news article goes on to further reference the mood-altering effect of dopamine, claiming that this results in the craving habits. As before, this does not directly follow the research of the paper, but rather draws upon a topic from the discussion section which has yet to be thoroughly studied.
5) The purpose of the paper was not to overturn previous research but rather to focus on a typically overlooked subject. The introduction explains how most research has so far focused on "understanding peripheral metabolic processes to explain how exercise may reduce subjective measures of appetite, and also eating restraint." However, this study was meant to examine the affect exercise has on specific eating behaviors, such as cravings as a result of various stressors. Because the original paper was not looking to overturn previous research the news article only references previous research as a means to explain the motivation behind the study.
6) Journalists very often couch science news items as "debates between equal sides", even if the weight of the evidence is not equal. Does the news article discuss alternative hypotheses that are not mentioned in the original paper? If so, does the news article give a measure of what degree of evidential support exists for either of the alternative models? The news article quotes Professor Adrian Taylor of the University of Exeter as a means to support its comparison of the effects of exercise on both food and drug cravings. While it is not a main topic in the original paper, the news article dedicates a majority of its focus to the idea that there are similar neurobiological processes in the reward center of the brain for food and drug cravings and that exercise could affect them both to the same degree. By tying this new research to previous research the news article can argue the idea that, since exercise was able to reduce drug cravings, it follows that it can reduce food cravings as well.