October 2008 LSAT Section 3 Question 22

In a study, one group of volunteers was fed a high–protein, low–carbohydrate diet; another group was fed a low–protei...

MJA7 on November 6, 2014

Explanation help

Please help explain why A is correct. I believe the discrepancy with the passage is that the conclusion specifically talks about body fat loss while the support talks only of weight loss. That being said I choose B as large amounts of protein consumption leads to gains in body fat. I believe I may be misunderstanding A do to the word 'compensates' and how it actually relates to the conclusion. Thanks for your help!

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Naz on November 13, 2014

The conclusion of the argument is: "the most effective way to lose body fat is to eat much protein and shun carbohydrates."

Why? A study looked at a group of volunteers that was fed a high-protein, low-carbohydrate diet and a group of volunteers that was fed a low-protein, high-carbohydrate diet. Both diets contained the same number of calories and each volunteer's diet before the experiment had contained moderate levels of proteins and carbohydrates. We are told that after ten days, those who were on the low-carbohydrate diet lost more weight than those on the high-carbohydrate diet.

So what's the biggest issue here? We are using evidence of results about general weight loss to conclude specifically about losing body fat.

Answer choice (A) is the correct answer because it explains that the reason people on the low-carb diet lost more weight, was not necessarily that they lost more body fat--since those on a high-carbohydrate diet were merely retaining more water.

So the weight that they retained was not necessarily more body fat. It could be that both groups lost 5lbs of fat, but the high-carbohydrate group gained 2lbs in water, therefore allotting for the results of the study, but showing that the conclusion was not necessarily true.

Answer choice (B) does not weaken because whether or not many people who consume large quantities of protein have significant overall weight loss is true doesn't effect the argument that is made due to the result of the study.

The argument proceeds by analyzing the results of a study and making a conclusion based off of that. Remember that "many" is a quantifier word that means "some." So the fact that some people who consume large quantities of protein nevertheless gain significant amounts of body fat has no bearing on the argument. This could be true while the conclusion of the argument still stands. Therefore, answer choice (B) does not weaken the argument.

Hope that clears things up! Please let us know if you have any other questions.

MJA7 on November 17, 2014

Great thanks