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“It suddenly struck me that that tiny pea, pretty and blue, was the Earth. I put up my thumb and shut one eye, and my thumb blotted out the planet Earth. I didn't feel like a giant. I felt very, very small.” – Neil Armstrong (1930-2012)

Fresh Reads from the Science 'o sphere!

Friday, August 10, 2007

Counterintuitive Science: Diet Foods And Health

Encouraged by John of Evolutionary Middleman, Fresh Brainz is proud to bring you a new series of articles: scientific results that run opposite to common sense!

I think these stories are important because there are people who think that science is just another type of dogma with its own rules and preconceived notions.

This view is incorrect because science doesn't follow a fixed worldview that is immutable over time.

Quite the contrary - scientific knowledge is constantly remodeled and improved as new hypotheses and evidence emerges. Even the much misunderstood "scientific method" is not cast in stone.

Stripped of all the technicalities, the scientific method is mainly used to check that results:

A. Are significant (not noise or statistical artifacts)

B. Be repeatable (not something that happens only once - other groups should be able to confirm your results)

C. Cannot be accounted for by alternative explanations (to support your proposed explanation)

What if the results turn out to be opposite to initial expectations or even common sense?

Dogma would immediately toss out those results. Science wouldn't.

Let's examine the results of two recent studies to see how this works:

1. In a large study to find out the major factors leading to cardiovascular disease, researchers at Boston University School of Medicine collected data from over 5000 middle-aged men and women from a town in Massachusetts.

They expected people who often drank diet soft drinks to have a lower risk of heart disease than people who drank sugary soft drinks.

Sure enough, the group of people who often drank sugary soft drinks showed a higher risk than others who drank infrequently.

But to their surprise, so did the group who often drank diet soft drinks! In fact the risks of both these groups are equal!

How can no-calorie drinks increase the risk of heart disease?

That utterly defies common sense.

The researchers know that correlation does not imply causation. They propose that people who drink diet soft drinks often have poor overall health habits and may be consuming more calories by eating more food. These people may also have a greater preference for sweet tasting food compared to others.

Here, you can see the limitation of this study. Since the actual caloric intake of the people is not known, alternative explanations to the observed effects cannot be ruled out. Thus a cause-and-effect relationship cannot be established.

These findings don't conclusively tell us whether diet drinks are good for health or not.

So - should we ditch the results?

2. Just two days ago, another research group at the University of Alberta observed a similar effect. They were studying the eating behaviour of young rats that were fed with low-calorie food and drinks.

Instead of becoming leaner, these rats became more obese!

The main reason is because the rats were overeating during their regular meals, thus consuming more calories anyway.

The researchers believe the mechanism is that young rats were incorrectly associating the taste of their food and its caloric content. This learning process leads to overeating behaviour as they mature.

They call this the "taste-conditioning process".

Older rats which grew up on regular food did not have such a tendency to overeat when they were fed diet food.

The researchers also suggest that their results may help explain the bizarre findings of the Boston study.

Again we can see the limitations in this study, because the experiments were done on rats and therefore aren't directly applicable to human beings.

Even if it was directly relevant, results from older rats predict that the people in the Boston study should not be affected by taste-conditioning, since they are middle-aged.

Indeed, more carefully designed studies are needed to support the hypothesis that diet foods can become a primer for poor eating habits.

But still...

Diet foods have the potential to make you fat?

Who would have guessed!?!!

5 Comments:

John - Evolutionary Middleman said...

Great stuff - keep it coming!

And excellent explanation of how counter intuitive findings are one of the ways science differentiates from dogma.

Here's how I make the ultimate differentiation -

Dogma - Old Testament, New Testament, Koran, etc.

Science - Evolution, Physics, Astronomy, etc.

Knowledge of Dogma arrived at by: Study (of the book of dogma), prayer, meditation. FAITH.

Knowledge of Science arrived at by:
Hypothesis, Predictions, Experiments, Evaluation, Confirmation. TENTATIVE ACCEPTANCE.

Lim Leng Hiong said...

Thanks!

More coming up... maybe I should make this a weekly feature.

John - Evolutionary Middleman said...

I agree. At least twice a month, but weekly would be better. This is good stuff.

Lab Rat said...

Actually, there's still another important part to the scientific method, in addition to the three you've already listed: Prediction and confirmation.

Counterintuitive science is an interesting theme - I might write about something from physics too, if and when I get off my lazy butt! :)

Lim Leng Hiong said...

Hi Lab Rat,

I'm looking forward to your articles about counterintuitive physics!