Researchers have found that when very overweight people, who tend to

Question

Researchers have found that when very overweight people, who tend to have relatively low metabolic rates, lose weight primarily through dieting, their metabolism generally remain unchanged. They will thus burn significantly fewer calories at the new weight than do people whose weight is normally at that level. Such newly thin persons will, therefore, ultimately regain weight until their body size again matches their metabolic rate.

The conclusion of the argument above depends on which of the following assumptions?

(A) Relatively few very overweight people who have dieted down to a new weight tend to continue to consume substantially fewer calories than do people whose normal weight is at that level.

(B) The metabolisms of people who are usually not overweight are much more able to vary than the metabolisms of people who have been very overweight.

(C) The amount of calories that a person usually burns in a day is determined more by the amount that is consumed that day than by the current weight of the individual.

(D) Researchers have not yet determined whether the metabolic rates of formerly very overweight individuals can be accelerated by means of chemical agents.

(E) Because of the constancy of their metabolic rates, people who are at their usual weight normally have as much difficulty gaining weight as they do losing it.

KarishmaB · Accepted Answer

It's something we call the ANT (Assumption Negation Technique)
To understand it, you first need to understand what an assumption is. An assumption is a  necessary missing premise . Premises support the conclusion. An assumption is also a premise but it is not given in the argument. Additionally, it is a necessary premise for the conclusion to hold true.

Say, take a simple example:

You are studying very hard. You are putting in 10 hrs a day. You work your way through many questions every day. You will pass the test.

Premises: 
You are studying very hard. 
You are putting in 10 hrs a day. 
You work your way through many questions every day.

Conclusion:
You will pass the test.

Assumption:
Is there a premise you NEED to make the conclusion hold?
"Hard work is sufficient to pass the test"

This is an assumption the author is making. He hasn't said this as such in his argument but he is assuming it. He is assuming that hard work is enough to pass.

The argument would be more complete if it looked like this:
You are studying very hard. You are putting in 10 hrs a day. You work your way through many questions every day. Hard work is sufficient to pass the test. Hence, you will pass the test.

What if I negate this assumption and make it: "Hard work is not sufficient to pass the test"
Can my conclusion still hold?
So you are studying very hard but hard work alone may not be enough. Can I say that you will pass the test? No. This is the point of negating the assumption. If the assumption is negated, the conclusion cannot hold. It is necessary that the assumption must hold if the conclusion has to hold.

If you negate an option and there is still a possibility that the conclusion can hold, it means the option is not an assumption.

halahpeno · Answer

Researchers have found that when very overweight people, who tend to have relatively low metabolic rates, lose weight primarily through dieting, their metabolism generally remain unchanged. They will thus burn significantly fewer calories at the new weight than do people whose weight is normally at that level. Such newly thin persons will, therefore, ultimately regain weight until their body size again matches their metabolic rate.

The conclusion of the argument above depends on which of the following assumptions?

A: Relatively few very overweight people who have dieted down to a new weight tend to continue to consume substantially fewer calories than do people whose normal weight is at that level. 

YES. We know from the question that the metabolism of these very overweight people remains unchanged despite their weight loss. As such, in order to maintain their lower weight, they will have to consume fewer calories than people whose normal weight is at that level (and whose metabolisms are faster). If these newly thinner very overweight people maintain the same calorie count as their normal weight counterparts, they will gain weight. The fact that few of them do means that they will regain weight until their body size matches their metabolic rate.

B: The metabolisms of people who are usually not overweight are much more able to vary than the metabolisms of people who have been very overweight.

Irrelevant.

C: The amount of calories that a person usually burns in a day is determined more by the amount that is consumed that day than by the current weight of the individual.

This contradicts the passage. The passage tells us that very overweight people tend to have slower metabolic rates. Slower metabolic rates means that they will burn fewer calories per day. This rate is unrelated to the amount of calories consumed and relies instead on the weight of the individual (of course, this is a bit tricky, since very overweight people's metabolic rates don't change a lot when they lose weight through dieting... sigh).

D: Reseachers have not yet determined whether the metabolic rates of formerly very overweight individuals can be accelerated by means of chemical agents.

Irrelevant.

E: Because of the constancy of their metabolic rates, people who are at their usual weight normally have as much difficulty gaining weight as they do losing it. 

Irrelevant.

I'd go with A because...

We know from the question that when very overweight people lose weight by dieting alone, their metabolism remains the same. That means that they cannot

jinino · Answer

The OA is A.

Here is the official explanation:

If, compared with people who have not been overweight, newly thin people burned fewer calories but also generally consumed fewer calories, one could not reliably conclude that the newly think people would regain weight. Therefore, the conclusion assumes that the newly thin do not generally consume fewer calories, making choice A the best answer.

The conclusion does not rely on differences in the variability of the metabolism (choice B), just on differences in the rate of metabolism, nor does it rely on the relative significance of different factors in determining how many calories a pwerson burns in a day (choice C). Neither does the conclusion assume anything about whether accelerators for the metabolism have been discovered (choice D), or about why some people have difficulty gaining weight (choice E).

gixxer1000 · Answer

I get A.

Premise: Overweight people who lose weight from dieting keep the same metabolism
Premise: They will burn less calories at the new lower weight than people who are normally at that weight.
---------------------------------------------------------------------------------------------------------
Conclusion: These people will regain weight until their body size matches their unchanged metabolism.

In order to reach that conclusion there is one premise (assumption) that we need. If the people are who lose weight by dieting will eventually regain weight than we HAVE to assume that they will stop dieting. Because if they continue to consume the same calories that they did to lose weight then they will not gain any of it back.

amit2k9 · Answer

Now between A and E use negation and see its effect of conclusion.Negation should undermine the conclusion.

E Not Because of the constancy of their metabolic rates, people who are at their usual weight normally  do not have  as much difficulty gaining weight as they do losing it. - Dosen't effect the conclusion at all.

A  No  very overweight people who have dieted down to a new weight tended to continue to consume substantially  more  calories than do people whose weight is at that level." - If this is true then how Newly thin people regained weight ? Hence this undermines the conclusion.

Hence A prevails.

ajit257 · Answer

thanks Amit ...I realized my mistake that i am overlooking the fact that assumtion is closely tied to conclusion ...awesome explanation.

KarishmaB · Answer

Amit has pretty much covered all the ground. Let me just add here that an assumption is a missing premise that is necessary for the conclusion to be true. The assumption has to be true for the conclusion to be true. Hence if you are lost between 2-3 choices, negate each choice. Once you negate an option, if your conclusion can still be true, it means the option is not an assumption. It is a very useful trick.

GMATPill · Answer

Here is a reason why (C) does not work.

(C) The amount of calories that a person usually burns in a day is determined more by the amount that is consumed that day than by the current weight of the individual.

Ask ourselves...does knowing the amount of calories burned in a day affect our argument that these dieters will actually REGAIN weight? We already know that dieters' calorie burn is LOWER than that of normal people for a given weight. If weight gain is determined by calorie INTAKE minus calorie burned, then the missing part to this equation is actually calorie INTAKE (or food eaten)...which is what (A) already addressed. Does (C) address calorie INTAKE?

Is (C) something the argument DEPENDS on? This is the "A vs Not A" Framework.

Does the following work:
 A case) Amount of calories burned is DETERMINED by amount consumed (rather than individual's weight) => dieters will REGAIN weight
 "Not A" case)  Amount of calories burned is NOT DETERMINED by amount consumed (instead, determined by individual's weight) => dieters will NOT REGAIN weight

Well, in the opposite case which is where calories burned is determined by individual's weight...then the calorie burns will be equal between avg person and the dieter because now the dieter has lost weight and become the same weight as the average person. So the amount of calories burned will equal. Thus, dieteres will NOT REGAIN weight. However, this conflicts with information in the passage...that since dieters' natural metabolism is lower, the calorie burn is LOWER than the average person. Thus conflicting information. Dieters' calorie burn cannot be LOWER than the average person AND the SAME.

Then in the "A" case, calorie burn is determined by amount consumed. Well, the dieters consume less than the average person. What does that mean for calorie burn? We know consumption is LINKED to calorie burn, but we don't know the direction. Is it dieters consume less so then calorie burn is HIGHER? or is it that the calorie burn is LOWER?

So you can see, (C) has a number of problems when the "A vs Not A" framework is applied.

Edvento · Answer

Conclusion: Newly thin persons will ultimately regain weight until their body size again matches their metabolic rate.

This is a find assumption question. The best way to approach it is to negate the assumption to see if the conclusion is negated or not.

(A) Relatively few very overweight people who have dieted down to a new weight tend to continue to consume substantially fewer calories than do people whose normal weight is at that level.

NOT (A) Almost all very overweight people who have dieted down to a new weight tend to continue to consume substantially fewer calories than do people whose normal weight is at that level.

If that be the case, then the newly thin people, who fewer calories will not gain weight even if their metabolism is low. This negates the conclusion. Hence this is the correct choice.

(B) The metabolisms of people who are usually not overweight are much more able to vary than the metabolisms of people who have been very overweight.

NOT (B) The metabolisms of people who are usually not overweight are much more stable than the metabolisms of people who have been very overweight.

This has no bearing on the conclusion. It only means that over weight people can have varying metabolism compared to the others.

The other choices are fairly straight forward. We don't even need to negate them to check. They are all out of context choices.

Regards,

Shouvik.

SVaidyaraman · Answer

In addition to the specific techniques of answering a particular type of question, a general aid to answering a question is to simplify the language. That will make life a lot easier.

For example ,

The premise of the argument: ".....They will thus burn significantly fewer calories at the new weight than do people whose weight is normally at that level."

The conclusion of the argument: "Such newly thin persons will, therefore, ultimately regain weight until their body size again matches their metabolic rate."

The gist of the premise can be noted down as follows: burn significantly fewer calories 
The gist of the conclusion can be noted down as follows: ultimately gain weight
 
An assumption is something which connects the two.

The gist of choice A: Few continue to consume few calories

We can see that A makes sense as  if overweight people burn fewer calories  and  continue to consume more calories at the reduced weight ,   they will ultimately regain weight.

The bold one is the premise, the underlined one is the assumption and the one in italics is the conclusion.

At least if one has a rough sense of the answer quickly, one can spend more time on it to check its correctness.

OptimusPrepJanielle · Answer

Researchers have found that when very overweight people, who tend to have relatively low metabolic rates, lose weight primarily through dieting, their metabolism generally remain unchanged. They will thus burn significantly fewer calories at the new weight than do people whose weight is normally at that level. Such newly thin persons will, therefore, ultimately regain weight until their body size again matches their metabolic rate.

The conclusion of the argument above depends on which of the following assumptions?

The conclusion is that overweight people who lose weight will regain it because their metabolism remains as low as it was prior to the weight loss.

A:  Relatively few very overweight people who have dieted down to a new weight tend to continue to consume substantially fewer calories than do people whose normal weight is at that level.  If formerly overweight people didn't maintain a low calorie diet, this would cause them to regain the weight, too. 
B: The metabolisms of people who are usually not overweight are much more able to vary than the metabolisms of people who have been very overweight.  We're concerned with people who have been very overweight. 
C: The amount of calories that a person usually burns in a day is determined more by the amount that is consumed that day than by the current weight of the individual.  The passage suggests that weight, and not food consumption determines calorie burn. 
D: Reseachers have not yet determined whether the metabolic rates of formerly very overweight individuals can be accelerated by means of chemical agents.  Chemical agents are out of scope. 
E: Because of the constancy of their metabolic rates, people who are at their usual weight normally have as much difficulty gaining weight as they do losing it.  People who are at their usual weight are out of scope.

SVaidyaraman · Answer

Fact:When very overweight people, who tend to have relatively low metabolic rates, lose weight primarily through dieting, their metabolism generally remain unchanged. i.e., they will thus burn significantly fewer calories at the new weight than do people whose weight is normally at that level.

Missing information:So to maintain the new weight they will have to consume substantially fewer calories than do people whose normal weight is at that level. But such people do not continue to do that . So
 
Conclusion:they will ultimately regain weight until their body size again matches their metabolic rate.

Choice A matches the missing information

BillyZ · Answer

Premise 1  : Very overweight people ( ↓ metabolic rate ) lose weight via dieting, metabolism remains unchanged.
 Premise 2  : Very overweight people burn  fewer calories  < normal people.
 Conclusion  : Very overweight people regain weight until body size =  metabolic rate

(A) Relatively few very overweight people who have dieted down to a new weight tend to continue to consume substantially fewer calories than do people whose normal weight is at that level.

Negate (A), Relatively few very overweight people who have dieted down to a new weight  DID NOT continue to consume substantially fewer calories  than do people whose normal weight is at that level.

Upon negating (A), it weakens the argument.

The correct answer is  (A) .

ballest127 · Answer

Hi expert.

I'm a little bit confused with the logic of negation.

For choice A , how to correctly negate the sentence.

In my opinion, it can be negated as:

"Not few = (Many) overweight people ..... continue to consume fewer calories ...." 
or 
"Not few = (None) overweight people ..... continue to consume 'more' calories ...." 
(as suggested by amit2k9)

In addition , in the amit2k9 's negated version , why we need to change the word from ' fewer' to 'more' ?

Expert please explain how exactly to negate the sentence correctly.

Thank you.

GMATNinja · Answer

As discussed in  this post , the problem with the negation technique is that some answer choices don't have obvious "opposites", and it's easy to come up with an incorrect negated statement.

Take statement (A) for example:

If we negate this, do we end up with "many" overweight people? "No" overweight people? "More" calories? Trying to properly "negate" this statement is confusing.

Instead, you could think of it in a simpler way: what happens if statement A is simply not assumed?

Well, in that case, it is POSSIBLE that  many  of those people (overweight people who have dieted down to a new weight) tend to continue to consume substantially fewer calories than do people whose normal weight is at that level. Therefore, those people would NOT "regain weight until their body size again matches their metabolic rate," contradicting the conclusion.

Put another way: by assuming that (A) IS true, we eliminate that possibility. This allows us to logically arrive at the conclusion. If, however, (A) is NOT assumed, then the logic does not hold.

The conclusion of the argument depends on statement (A), so that is the correct answer.

I hope this helps!

ballest127 · Answer

Hi  GMATNinja ,

Thank you for your kind explanation on my question.

However, I am still confused by some part of your explanation.

You recommend that we don't use negation and state that " Instead, you could think of it in a simpler way: what happens if statement A is simply not assumed? "

I'm not sure that the above approach is the same as "negation".

In addition, you change the word "few" to "many" (of those people .....). 
Can I assume that you negate it.

Please explain.

GMATNinja · Answer

Check out this post for example of negation gone wrong. The problem with negation comes when it is used as a way to side-step thinking really hard about an answer choice. If you aren't being careful with your negation and lazily add/remove a no/not or swap something like "all" with "none/few/most", you might not be truly "negating" the answer choice. I find that asking, "What is possible if this is NOT assumed?" instead of "What is the opposite of this statement?" can help students avoid that pitfall. This is, admittedly, a subtle difference, and those questions often have the same or similar answers. Just make sure that, when applying negation, you are thinking very carefully about what you are doing instead of lazily "multiplying the sentence by negative 1", so to speak

.

mykrasovski · Answer

nightblade354   GMATNinja  why is (D) incorrect? Let's say researchers find the chemicals to accelerate the metabolic rate of formerly overweight people. If so, then the overweight people, after loosing weight, will take medication or whatever chemicals to accelerate their metabolic rate. In that case, they will continue burning calories at a high rate and, thus, they will not re-gain weight. So, the argument is broken.

nightblade354 · Answer

Researchers have found that when very overweight people, who tend to have relatively low metabolic rates, lose weight primarily through dieting, their metabolism generally remain unchanged. They will thus burn significantly fewer calories at the new weight than do people whose weight is normally at that level. Such newly thin persons will, therefore, ultimately regain weight until their body size again matches their metabolic rate.

The conclusion of the argument above depends on which of the following assumptions?

(D) Researchers have  not yet  determined whether the metabolic rates of formerly very overweight individuals can be accelerated by means of chemical agents.

So who cares about the fact that they have determined this? We have to make so many assumptions to justify your comments above. Do not make the answer work for you by filling in information (like taking a medication). Our conclusion is that because metabolism is unchanged, people will regain weight. If we take (D), maybe it speeds it up by .00000001% and doesn't do anything; maybe the patients haven't heard of this medicine, or can't afford it, or can't take it, ect. I think your reasoning about giving an alternate reason as to why the weight will be kept off is fine, but this answer isn't it.

Researchers have found that when very overweight people, who tend to

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