Dietary researcher: A recent study

Answer choices

1. A

   Correct65% picked this

   North Americans, on average, consume a higher number of calories than the optimal number of calories

   Why this is right

   The author's argument is assuming a difference between lab animals and the average North American: the lab animals are overeating, which is why reducing their caloric intake brings them down to a normal level that extends their life span. But reducing caloric intake for North Americans won't extend their life span, because they aren't overeating (<-- that's the assumption) This answer blows up that assumption. If North Americans are also generally eating too much, then reducing our caloric intake could bring us down to a normal level and potentially extend our longevity, just as it did with lab animals.

   Skill tested: Weaken · how this choice captures the argument's function is the move to repeat next time.

   65%
2. B

   No Impact9% picked this

   North Americans with high-fat, low-calorie diets generally have a shorter life expectancy than North Americans

   This statement makes it seem like reducing fat might extend life expectancy, but this argument is about whether reducing calories would extend life expectancy (both groups being compared in this answer are on low-calorie diets).

   9%
3. C

   No Impact12% picked this

   Not all scientific results that have important implications for human health are based on studies

   This is an incredibly weak statement, so it's unlikely to be a correct answer on Str / Wkn / Pdx. It says "at least one scientific result with important implications for human health was not based on studies of lab animals". Cool. That doesn't tell us anything about calories / North Americans / life expectancy, etc.

   12%
4. D

   Too Weak: some11% picked this

   Some North Americans who follow reduced-calorie diets

   This says there is at least one North American who follows a reduced calorie diet and has a long life span. While that does go in our desired direction of arguing that "reducing calories for the average North American could extend life spans", it is but one data point. It doesn't have as strong an effect as (A), which is telling us that "most North Americans are currently consuming more calories than is optimal" .

   11%
5. E

   Unclear Impact4% picked this

   There is a strong correlation between diet and longevity in some

   This says that for at least one species of animal, there's a strong correlation between diet and longevity. Diet is a broad term that encompasses the types of food one eats. This argument is more about the quantity than the type. It's about how many calories one eats. So we have no idea how this answer specifically relates to caloric intake. If one person got 2000 calories a day from fruits, vegetables, and protein and another person got 2000 calories from candy, they would have the same caloric intake, but very different diets. The former diet might be strongly correlated with longer lifespan, but that would have nothing to do with caloric intake.

   4%