A group of experimental subjects participated in an intermittent fast

Here is the OE from MGMAT:

(1) Identify the Question Type

The question stem asks what would be most useful in evaluating the argument, so this is an Evaluate the Argument question.

(2) Deconstruct the Argument

Subjects who ate all their food within six hours of waking lost significant weight. Why did this happen? The author concludes that eating within a condensed time period must prompt the body to burn more calories. However, there are many other possibilities that the author doesn’t address. Maybe the subjects ate differently or engaged in activities that burned more calories. True, the argument states that calorie consumption and exercise patterns remained the same, but perhaps the source of the calories matters, or perhaps the subjects burned calories through non-exercise activities (standing up at a concert vs. sitting down at a restaurant). Maybe it was important that the subjects didn’t eat before going to bed, or maybe eating in one short burst prevents the body from digesting all of the food.

(3) State the Goal

In an Evaluate the Argument question, the goal is to choose a question or piece of information that would make it easier to determine if the conclusion is valid. What would test the author’s assumptions here? There are so many possibilities that it’s difficult to predict exactly what the right answer choice will say, but it should introduce some alternative explanation for the subject’s weight loss. Notice that it won’t help to look at overall calorie consumption, because the argument states that the subjects consumed the same number of calories as before.

(4) Work from Wrong to Right

(A If this were true, perhaps the subjects would have consumed fewer calories, but the premise states that calorie consumption remained the same, so this is out of scope.

(B) The conclusion is only about the effect of eating in short periods on calorie consumption. The argument doesn’t make any claims about safety, nor does it advocate the practice of intermittent fasting, so it isn’t necessary to determine whether this practice is safe to evaluate the argument.

(C) Even if most people are unable to fit a full day’s calories into six hours, the subjects in the study did just that. The argument is about the effect of eating all one’s calories over a short period, not whether intermittent fasting could be adopted more widely without calorie reduction, so it’s not necessary to make this determination.

(D) The argument is only concerned with the effects of timing on calorie burning, so hunger is out of scope.

(E) CORRECT. This could provide an alternative explanation for the study result. Perhaps people burned more calories simply because they ate earlier in the day and not because of the condensed time period. If this wouldn’t happen in the evening, perhaps the author’s conclusion is not true in general. For instance, perhaps consuming all one’s calories in the last six hours of the day would lead to weight gain, not loss. In that case, it wouldn’t appear that simply eating over a reduced period of time lead to increased calorie burning.