Average hours of television viewing per American have rapidly increase

I don't understand how OA weakens the argument.

Let, thirty years ago, Americans watched television 3 hours per day, but 99% of these Americans did not take fast food. Now Americans watched television 5 hours per day and still 99% of these Americans do not take fast food. Nevertheless, they become obese.

On the otherhand, the number of fast food restaurants might be increased because of increased volume of consumption by the remaining 1% Americans.

So, the increase of number of fast food restaurants does not weaken the argument.

As per my understanding,
The argument links rise in obesity to the number of hours of TV viewing in America.
Since we need to weaken this link, we can provide an alternate explanation for the rise in Obesity

Option B (Over the last 30 years, there has been an increase in the number of fast food restaurants in America)
provides that alternate explanation, and in turn weakens the link of Obesity to TV Viewing.

Hope that helps!

The argument links rise in obesity to the number of hours of TV viewing in America. But, how does option B link rise in obesity to the number of fast food restaurants in America without assuming that all people increase their intake of fast food, a trend may not be true according to my previous post?

Over the last 30 years, a lot of things happened in the world. I presume all of these are not linked to the rise in obesity.

Am I correct

Hi Bro, I am no expert but let me give it a try

First and most important thing: If GMAT question says X is responsible for Y, then its ABSOLUTE. Nothing else can cause Y other then X.

Also, if the GMAT says in past 30 years lot of restaurants opened, it means that STRICTLY only restaurants increased. We do not presume that people started exercising or dieting. The option "B" is just giving us an alternate assumption that restaurants caused the obesity rather than televisions.

Hope that helps.
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Kudos if it helps!

I am really confused b/w B and E - both lead to weakening, though E weakens more. Expert opinions please on how to solve this.
One the first things for CR which I learnt was that correlation doesn't mean causation.
So, if there is a spike in TV watching and spike in obesity; it doesn't mean one causes the other. Similarly, for B as well, rise in the number of fast food chains doesn't mean it directly causes obesity.
E however, says there is a rise in the number of junk food commercials - this means even if they do limit or change TV watching behavior; if there is a link between the between watching TV and buying junk food.
Please explain the flaw in my reasoning in order to understand the OA.

OFFICIAL EXPLANATION:

To tackle this question, first identify the conclusion you’re supposed to weaken and the premises the author states or implies to reach that conclusion. The conclusion is pretty easy to spot. The last thought of the argument is that Americans must limit their hours of television viewing to curb the rise in obesity. The author makes this judgment using the following evidence:

» The author directly states that the number of television viewing hours has increased over the last 30 years.
» According to the author, the number of obese Americans has also increased.
» The author implies that television viewing causes obesity.

To weaken the argument that Americans have to reduce their television watching, you have to find the answer choice that shows that there’s another cause for the rise in obesity.

You may have been tempted to select Choice (A) because it shows that television watching may be less fat-producing than another activity, sleeping. But it doesn’t give you another reason for the rise in obesity. Choice (A) could be correct only if it showed that Americans were sleeping more than they were 30 years ago. It doesn’t, so move on.

On the other hand, stating that during the same time period, the number of fast-food restaurants also increased introduces another possible cause of obesity and weakens the conclusion that Americans have to stop watching so much TV to get slimmer. Maybe it’s the popularity of fast food that’s the culprit! Choice (B) is a better answer than Choice (A), but read through all the possibilities before you commit. Choice (C) is wrong because there’s nothing in the argument that suggests that the type of television Americans watch affects their obesity; nor does Choice (C) show that viewing patterns have changed over the last three decades. Choice (D) is also out because it doesn’t correlate what’s happening in Japan with what’s happening in America. You don’t know whether Japanese citizens weigh more now than they did 30 years ago, so the information in Choice (D) is useless.

If the question had asked you to strengthen the conclusion, Choice (E) would be a good option. It shows a reason that increased television watching could cause obesity. But the question asks you to weaken the conclusion, so Choice (B) is the best answer. It’s the only one that shows that another cause could be to blame for the rise in obesity.

Average hours of television viewing per American have rapidly increased for more than three decades. To fight the rise in obesity, Americans must limit their hours of television viewing.

Which of the following, if true, would most weaken the author’s conclusion?

we need to see, if there can be another reason for people getting fat, except watching TV.

(A) A person burns more calories while watching television than while sleeping. -> Sleeping...Incorrect.
(B) Over the last 30 years, there has been an increase in the number of fast food restaurants in America. -> It is a strong reason. Let's keep it.
(C) Americans spend most of their television time watching sports events rather than cooking shows. -> Irrelevant.
(D) Television viewing in Japan has also increased over the past three decades. -> Irrelevant.
(E) Studies show that the number of television commercials that promote junk food has risen over the past ten years. -> Irrelevant.

So, I think B.