In a study, one group of volunteers was fed a high-protein, low-carboh

Question

In a study, one group of volunteers was fed a high-protein, low-carbohydrate diet; another group was fed a low-protein, high-carbohydrate diet. Both diets contained the same number of calories, and each volunteer’s diet prior to the experiment had contained moderate levels of proteins and carbohydrates. After ten days, those on the low-carbohydrate diet had lost more weight than those on the high-carbohydrate diet. Thus, the most effective way to lose body fat is to eat much protein and shun carbohydrates.

Which one of the following, if true, most weakens the argument above?

(A) A low-protein, high-carbohydrate diet causes the human body to retain water, the added weight of which largely compensates for the weight of any body fat lost, whereas a high protein, low-carbohydrate diet does not.

(B) Many people who consume large quantities of protein nevertheless gain significant amounts of body fat.

(C) A high-protein, low-carbohydrate diet will often enable the human body to convert some body fat into muscle, without causing any significant overall weight loss.

(D) In the experiment, the volunteers on the high carbohydrate diet engaged in regular exercise of a kind known to produce weight loss, and those on the low-carbohydrate diet did not.

(E) Many of the volunteers who had been on the low-carbohydrate diet eventually regained much of the weight they had lost on the diet after returning to their normal diets.

Bunuel · Accepted Answer

EXPLANATION FROM Fox LSAT

The first problem I see with the logic here is that the conclusion goes way off the rails with “the most effective way.” The study only compared two groups: high-carb/low-protein vs. low-carb/high-protein. How can the conclusion possibly say “the most effective way,” if it only looked at two ways? In order to make that conclusion, you would have had to study every possible method of losing body fat!

We’re asked to weaken the argument, and the above features such a huge problem with the reasoning that we should start by looking for that particular issue in one of the answer choices. If we can’t find it, then we’ll reconsider and look for another flaw.

A) This isn’t what we’re looking for, but it still might be worthy of consideration. Let’s get through the rest of the answer choices and if something awesome doesn’t jump out at us, we’ll come back to this one.

B) Well, yeah. Of course you can ruin your diet by “consuming large quantities of protein” alongside large quantities of carbs, fat, alcohol, and everything else. If you do that, you’re going to gain body fat. But that’s not the point of the study, because the study was about two groups that were on a fixed total caloric intake. No way is this it.

C) This would only strengthen the idea that the high-protein/low-carb diet is good for lowering body fat. We’re looking for a weakener, so this is out.

D) This would also strengthen the argument, not weaken it. If the high-carb people were also exercising, and they didn’t lose weight, then this would support the idea that low-carb is superior. We’re looking for a weakener, so this is out.

E) Regaining the weight is simply irrelevant. The conclusion of the argument wasn’t about keeping fat off, it was only about losing fat in the first place. No way.

I didn’t find exactly what we were looking for, but I really hate B through E. So now we can reconsider A. Here’s my case for it: If it’s true that the low- protein/high-carb diet causes you to retain water, then it’s possible that your body  did  lose fat even if you didn’t lose weight. The conclusion of the argument wasn’t about losing weight, it was about losing fat. If A is true, then it’s possible that the low-protein/high-carb diet was actually better than the high-protein/low-carb diet for losing fat. That’s the best weakener of the bunch.

So A is our answer

100mitra · Answer

Correct Option A

In a study, 
 Group 1  - high-protein, low-carbohydrate diet; 
 Group 2  - low-protein, high-carbohydrate diet. 
Both diets contained the  same number of calories , and 
each volunteer’s diet had contained  moderate levels of proteins and carbohydrates . 
After ten days, 
- those on the  low-carbohydrate diet  
 had lost more weight than  
- those on the  high-carbohydrate diet.  
 Conclusion:   the most effective way to lose body fat is to eat much protein and shun carbohydrates
 Assumption:  Fat loss is weight reduction.

Which one of the following, if true,  most weakens the argument  above?

(A) A low-protein, high-carbohydrate diet causes 
( The human body to retain water ), 
the added weight of which largely compensates for the weight of any body fat lost, 
whereas a high protein, low-carbohydrate diet does not.
 Correct:  Gives details related to Deit and highlight Despite weight loss by fat burning or reduction, but high-water intake which might have maintained the weight, this counters the conclusion.

(B) Many people 
who consume  large quantities of protein  
nevertheless,  gain significant amounts of body fat .
 Flaw:  gives details about Diet, and more emphasis on protein intake, this stem actually fails to address about weight reduction or weight gain.

(C) A high-protein,  low-carbohydrate diet  will often enable 
the human body to  convert some body fat into muscle , 
without causing any significant  overall weight loss .
 Flaw : this gives details about Diet, but gives more details opposite to conclusion (low carbohydrate = fat loss = no weight reduction)

(D) In the experiment, 
the volunteers on the high carbohydrate diet engaged 
in  regular exercise of a kind known to produce weight loss , and 
those on the low-carbohydrate diet did not.
 Wrong:  gives no details about Diet or part of experiment, but try to adds another one part of experiment about excercise, and comparison between two groups, fails to address conclusion relate through diet about weight reduction.

(E)  Many of the volunteers  
who had been on the low-carbohydrate diet 
eventually regained much of the weight they had lost on the diet 
 after returning to their normal diets 
 Flaw:  gives details about post experiment and regain of normal past diet of volunteer, it actually strengthens the conclusion, saying it was low carbohydrates and high protein, which helped to reduce significantly reduction in weight

asishron29181 · Answer

Group1: HP LC
Group2: LP HC
Group1 lost weight.

Conclusion: Thus, the most effective way to lose body fat is to eat much protein and shun carbohydrates.

We need to weaken the conclusion over here.

(A) A low-protein, high-carbohydrate diet causes the human body to retain water, the added weight of which largely compensates for the weight of any body fat lost, whereas a high protein, low-carbohydrate diet does not.  - Correct. This weakens the conclusion stating why group 2 did not lose weight.

(B) Many people who consume large quantities of protein nevertheless gain significant amounts of body fat. - Irrelevant.

(C) A high-protein, low-carbohydrate diet will often enable the human body to convert some body fat into muscle, without causing any significant overall weight loss. - Irrelevant. We are not concerned about the muscles here.

(D) In the experiment, the volunteers on the high carbohydrate diet engaged in regular exercise of a kind known to produce weight loss, and those on the low-carbohydrate diet did not. - Incorrect. This doesn't weaken the conclusion in any sense.

(E) Many of the volunteers who had been on the low-carbohydrate diet eventually regained much of the weight they had lost on the diet after returning to their normal diets. - Incorrect. We are not concerned about the post diet weight gain/loss.

IMO A

IanStewart · Answer

Yes, the answer is A, because the evidence supports the idea that one diet helps to lose weight, but the conclusion of the argument is not about losing weight, but instead talks about how "to lose body fat". Those aren't necessarily the same thing, and if A is true, they definitely are not the same thing, and the conclusion doesn't follow from the facts.

There's something tempting about answer D here, though it's obviously not the right answer to a test question like this. D at first appears to strengthen the argument rather than weaken it -- even though the high-carb dieters were exercising, they still didn't lose as much weight as the high-protein dieters, so that seems to reinforce the idea that a high-protein diet helps to lose weight or body fat. So at first glance D seems a very bad answer to the question. But if the researchers, studying differences in diet, weren't controlling factors like exercise that you'd obviously need to control in a study like this, what other methodological errors were they making? Answer D suggests to me that this was an incompetently conducted study, which means its conclusions really aren't reliable. So in the real world, D seems like a good answer to a question like this. On the GMAT or LSAT, however, I don't think I've ever seen a CR question where you weakened an argument by attacking the competence of the people making the argument or collecting the supporting evidence, so this line of reasoning isn't likely to matter on the test.

Sumi1010 · Answer

This a tricky CR question. 
The idea is to read the argument and the choices very carefully.

Study:  Those on high-protein, low-carbohydrate diet -  lost more weight  than - Those on the high-carbohydrate diet. 
 Conclusion  - The most effective way to  lose body fat  is to eat much protein and shun carbohydrates .

Prethink:  
The argument assumes that the body weight is primarily due to body fat. 
 What if body weight is reduced due to dehydration?  - The argument won't stand anymore.

Let's look at the choices

(A) A low-protein, high-carbohydrate diet causes the human body to retain water, the added weight of which largely compensates for the weight of any body fat lost, whereas a high protein, low-carbohydrate diet does not.
 In case of high-carbohydrates, the body weight is NOT reduced because body fat lost is compensated by water retained. 
In other words, body weight remains same despite the fat is reduced. 
i.e. body weight is NOT primarily due to body fat. 
The choice attacked the assumption (a mandatory consideration) on which conclusion lies. 
Thus, the argument is weakened. 
(B)  Many  people who consume large quantities of protein nevertheless gain  significant  amounts of body fat.
 If so, the choice seems to challenge the argument's conclusion that consuming proteins will help losing body fat.
We must be aware of half-information choice.
 Are these people the part of of the study? If not, they might not have had low-carbohydrate diet.

(C) A high-protein, low-carbohydrate diet will often enable the human body to  convert some body fat into muscle , without causing any significant overall weight loss.
 The argument assumes that the body weight is primarily due to body fat. 
The choice assists on the same. 
Strengthening the argument. 
(D) In the experiment, the volunteers on the high carbohydrate diet engaged in  regular exercise  of a kind known to produce weight loss, and those on the low-carbohydrate diet did not.
 The conclusion implies that the volunteers on the high carbohydrate diet could not match those on low-carbohydrate diet in weight losing (irrespective of the exercises mentioned here).Thus, the choice adds nothing to the argument. 
(E) Many of the volunteers who had been on the low-carbohydrate diet  eventually regained  much of the weight they had lost on the diet  after returning to their normal diets. 
 The choice is tempting. If the effect is temporary, then the conclusion is weakened. 
However, note the phrase "after returning to their normal diets" . The conclusion does not say anything about "quitting" the low-carbohydrate diet. 
 If this phrase were not there, this choice would have weakened the conclusion.

Takeaways - 
Note 1: In such study-based conclusions, we must focus on the key words that the conclusion derive. 
Note 2 : In case there is a conclusion that says "doing X will do Y" , ensure that Y is not a "temporary" impact of X.

IMO  A

unraveled · Answer

In a study, one group of volunteers was fed a high-protein, low-carbohydrate diet; another group was fed a low-protein, high-carbohydrate diet. Both diets contained the same number of calories, and each volunteer’s diet prior to the experiment had contained moderate levels of proteins and carbohydrates. After ten days, those on the low-carbohydrate diet had lost more weight than those on the high-carbohydrate diet. Thus, the most effective way  to lose body fat is to eat much protein and shun carbohydrates .

Which one of the following, if true, most weakens the argument above?

Last line is the conclusion. HPLC is required to help lose body fat.

(A) A low-protein, high-carbohydrate diet causes the human body to retain water, the added weight of which largely compensates for the weight of any body fat lost, whereas a high protein, low-carbohydrate diet does not. - CORRECT. Initially, it looked what good use of water is there. But this option does explain that body fat is lost even if weight is not.

(B)  Many  people who consume large quantities of protein nevertheless gain significant amounts of body fat. - WRONG. If 'many' stands for exceptions than this option is a waste and if not then this is good candidate. But such an open option is not worthy generally.

(C) A high-protein, low-carbohydrate diet will often enable the human body to convert  some body fat  into muscle, without causing any significant overall weight loss. - WRONG. How much is 'SOME' ?. It did waste my time in deciding whether it is good enough.

(D) In the experiment, the volunteers on the high carbohydrate diet  engaged in regular exercise  of a kind known to produce  weight loss , and those on the low-carbohydrate diet did not. - WRONG. First, an external factor i.e. 'exercise' and second 'weight loss' instead of body fat loss.

(E) Many of the volunteers who had been on the low-carbohydrate diet eventually regained much of the weight they had lost on the diet  after returning to their normal diets . - WRONG. Not normal diets but HPLC.

Answer A.

Shenron · Answer

Hi  ParamjitDasGMAT ,

Kindly assist on this question.

ParamjitDasGMAT · Answer

Sure,  Shenron ,

I am happy to help.

So the idea is that although those on a high carb diet lost less WEIGHT, they still might have lost a similar/greater amount of FAT. The reason their weight loss wasn’t as high was because of increased water retention. So it is playing on the discrepancy/gap between weight loss and FAT loss.

Hope this helps.

AbhishekP220108 · Answer

Hi  Shenron

Let me try to help

In a study, one group of volunteers was fed a high-protein, low-carbohydrate diet; another group was fed a low-protein, high-carbohydrate diet.-A study was introduced, two groups are given different diet. Lets call it One with D1 low protein high carb, Other one D2 high protein low carb. Thats all we know till here

Both diets contained the same number of calories, and each volunteer’s diet prior to the experiment had contained moderate levels of proteins and carbohydrates. Lets take both D1 and D2 has 1500kcal, each volunteer has taken before moderate level(between low and high) of protein and carb

After ten days, those on the low-carbohydrate diet had lost more weight than those on the high-carbohydrate diet.- After 10 days body weight was noted volunteers on D2 lost more weight that D1 volunteers

Thus, the most effective way to lose body fat is to eat much protein and shun carbohydrates.-Author concludes if you intake more protein and remove carb thats the most effective way to loose body fat.

Which one of the following, if true, most weakens the argument above?

Questions asks for a weakner

So while reading the argument, I had several doubts

1. How the author said its the most effective way? Does he really went on to all other ways because we are not told about other ways.

2. Argument doesn't tell us about the previous weight of volunteers, what if there is error in measurement.

3. What if along the diet D2 group is doing something else to loose weight.

There are several other. Now let's evaluate option choice if any option create a doubt on conclusion thats our choice

(A) A low-protein, high-carbohydrate diet causes the human body to retain water, the added weight of which largely compensates for the weight of any body fat lost, whereas a high protein, low-carbohydrate diet does not.- This talks about the compensation of weight, so loosing body fat but retaining weight. Keep it because we doesn't have enough reason to reject or select.

(B) Many people who consume large quantities of protein nevertheless gain significant amounts of body fat.- it just talks about large protein, what if these are taking Carbs in large amount too.. so not a weakner in my view.

(C) A high-protein, low-carbohydrate diet will often enable the human body to convert some body fat into muscle, without causing any significant overall weight loss.- without causing significant overall weight loss is not point of concern. Even if it let us loose 2 3 kg and D1 let only 1 kg, conclusion still holds

(D) In the experiment, the volunteers on the high carbohydrate diet engaged in regular exercise of a kind known to produce weight loss, and those on the low-carbohydrate diet did not.- this can be strengthener because if people on D1 still lost less weight doing workout, it proves D2 is efficient

(E) Many of the volunteers who had been on the low-carbohydrate diet eventually regained much of the weight they had lost on the diet after returning to their normal diets.- Regained fine but they did lost the weight. What if they didnt follow the D2. So not a weakner

Even though I didnt like A and I too had eliminated in 1st go but while doing so other options are not helpful.

Lets check A again

A low-protein, high-carbohydrate diet causes the human body to retain water, the added weight of which largely compensates for the weight of any body fat lost, whereas a high protein, low-carbohydrate diet does not.- it says the group following D1 lost the same weight the but lost weight was compensated by retaining the water. So as per the conclusion which is about body fat D1 is equally effective if I am not wrong

Hope this helps

agrasan · Answer

Hi  KarishmaB   MartyMurray

(B) Many people who consume large quantities of protein nevertheless gain significant amounts of body fat.

Is (B) wrong because we don't know those  "many people"  had  low  carbohydrates or  high  carbohydrates in their diet so (B) isn't directly relevant for our conclusion?

guddo · Answer

In a study, one group of volunteers was fed a high-protein, low-carbohydrate diet; another group was fed a low-protein, high-carbohydrate diet. Both diets contained the same number of calories, and each volunteer’s diet prior to the experiment had contained moderate levels of proteins and carbohydrates. After ten days, those on the low-carbohydrate diet had lost more weight than those on the high-carbohydrate diet. Thus, the most effective way to lose body fat is to eat much protein and shun carbohydrates. 
 
Which one of the following, if true, most weakens the argument above?

The argument treats “lost more weight” as proof of “lost more body fat,” and then generalizes that diet as the best way to lose body fat.

(A) A low-protein, high-carbohydrate diet causes the human body to retain water, the added weight of which largely compensates for the weight of any body fat lost, whereas a high protein, low-carbohydrate diet does not.

If the high carbohydrate group retains extra water, then the scale can show less weight loss even if they lost a similar amount of fat. That means the observed difference could be mostly  water weight , not a real difference in fat loss.  This most weakens.

(B) Many people who consume large quantities of protein nevertheless gain significant amounts of body fat.

This is about what happens in other situations, not in a controlled comparison with equal calories, and it does not show the study’s extra weight loss was not fat.

(C) A high-protein, low-carbohydrate diet will often enable the human body to convert some body fat into muscle, without causing any significant overall weight loss.

This says the low carbohydrate diet might not change total weight much, but in the study it did. It also does not undercut the key jump from weight loss to fat loss.

(D) In the experiment, the volunteers on the high carbohydrate diet engaged in regular exercise of a kind known to produce weight loss, and those on the low-carbohydrate diet did not.

If anything, this makes the result look even more impressive for the low carbohydrate diet, since the other group had an extra reason to lose weight.

(E) Many of the volunteers who had been on the low-carbohydrate diet eventually regained much of the weight they had lost on the diet after returning to their normal diets.

Regaining weight later does not show they failed to lose body fat during the ten days, and the conclusion is about what loses fat, not what prevents regain after stopping.

Answer: (A)

egmat · Answer

You're right that (B) is irrelevant, but let me sharpen  exactly why .

The Argument's Structure: 
-  Observed:  Low-carb group lost  more weight  than high-carb group
-  Concluded:  Low-carb is the  most effective  way to lose  body fat

This is a  comparative argument  - it's comparing two diets.

Why (B) Fails:

(B) says: "Many people who consume large quantities of protein  nevertheless  gain significant amounts of body fat."
 The problem:  This only tells us about  ONE  group (high-protein eaters). It gives us  zero  information about how they compare to high-carb eaters.
Even if those "many people" were eating low-carb, we'd still need to ask:  "Compared to what?"  Maybe high-carb eaters gain  even more  fat!

Key Rule:  To weaken a comparative conclusion, you must attack BOTH sides of the comparison OR show the measurement is flawed.  (B) only mentions one side - it's out of scope.

Why (A) Works: 
(A) attacks the  measurement itself :
- Low-carb diets cause  water loss 
- High-carb diets cause  water retention 
-  Therefore:  The extra weight lost by the low-carb group was likely  water, not fat

This breaks the link between "lost more weight" and "lost more fat."

Correct approach:  When you see a  comparison  in the conclusion, ask: "Does this answer choice address  both  sides, or just one?"

Answer: A

Hope this helps!

KarishmaB · Answer

Yes, 'large amount of protein' tells us nothing about other habits of those 'many people.' Perhaps those many people don't exercise and consume large amounts of fat and carbs as well.

vasu1104 · Answer

two diet groups. one with high protein and low carbs. the other is low protein and high carbs. 
 before experience moderate level of protein and carbs in diet. 
 both diet with same calories. 
 after 10 days, people with low carbs diet lost more weight than high carbs. 
 Conclusion- effective ways to lose body fat is to eat more protein and low carbs.

the conclusion is about losing body fat with low carbs and the reasoning is losing more weight. so they are connecting losing weight with losing fat.

A that means people with high carbs lost fat but because of water added some weight. so this makes the conclusion weaker for suggesting to go for low carbs. perfect. 
 B but does it have low or high carbs. we dont know so remove. 
 C this somewhat strengthen it. basically you are losing fat by converting it into muscle. so make sense to go with plan. 
 D this also strengthen it. without exercise these people lost fat so make sense to go with idea. reject. 
 E this has no impact at all. also they might have controlled their fat despite gaining weight.

In a study, one group of volunteers was fed a high-protein, low-carboh

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In a study, one group of volunteers was fed a high-protein, low-carboh

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