CR: Overweight - Metabolic rates

EdWood wrote:Researchers have found that when very overweight people, who tend to have relatively low metabolic rates,
lose weight primarily through dieting, their metabolisms 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?

Ed - Here's the simplified argument for you.

Overweight people are fat because of low metabolic rate.
When Overweight people lose weight by EATING LESS their metabolic rate continues to remain the same.
So eventually they will regain their lost weight.

What is an assumption here?

(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.

Negation test: (If by reversing the statement our conclusion falls apart then that answer choice is our conclusion - The theory behind this is Premises + Assumption = Conclusion, so Premises + Not an assumption cannot yield a credible conclusion)

Lets reverse this statement

A Large number of 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.

Well so what will happen? They will continue to lose weight indefinitely and eventually their weight will reach 0

This totally destroys our conclusion that they will regain their weight. So this is our answer.


(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.

2 problems, firstly, this statement talks about people who are usually NOT overweight, our conclusion deals with overweight people. Secondly, how metabolism varies does not help us at all, we are only concerned with whether overweight people regain their weight.

(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.

I guess Ans B but correct ans is A.

Rest of the options are out of scope. You can try negation test for yourself. Let me know if you run into any trouble

Question stem is confusing, anyone who can shed light on this. - I hope i have turned on the flood light for you.

Thanks
Ed