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hdwkt: the science behind nutritional advice

9 Nov

The past few years I’ve been teaching biochemistry of the macromolecules (Chapter 3 in Campbell Concepts and Connections) alongside enzymes and digestion (Chapters 5 and 21 respectively). To me, these topics fit together tighter than a-bungarotoxin at the neuromuscular junction. I wish more textbooks would organize themselves this way, rather than oh so unoriginal small – big sequence of topics. Start with atoms, end with ecology…clever. But that’s another day.

A few items recently caught my eye regarding nutritional advice, and I’m mulling over how to implement these into the classroom along the lines of hdwkt (how do we know this?). One is a video a student showed me of  a 4 year old McDonald’s hamburger that looks pretty much like a 4 hr old hamburger (there’s lots of other videos on this same theme).

While her props are indeed provocative, this isn’t really fair to the burger or fries. Before I start, I’m not in any way suggesting that McDonald’s is healthy or great for you, or that any burger and fries are great for you. However, I do take issue with her illogical argument for avoiding McDonald’s.

Her argument goes something like this:

McDonald’s burger doesn’t rot
Food rots
Therefore, McDonald’s burger is not food

Her corollary to that seems to be:

McDonald’s non-food burger doesn’t break down easily in the open air under normal household conditions
If non-food burger can’t break down outside the body, it can’t break down inside the body
If the burger can’t break down, your body stores it (in your thighs)

There’s lots of ways this line of reasoning is flawed. Skipping over the philosophical debate over a definition of ‘food’, even a rudimentary working knowledge of the digestive system would tell you that the environment in your stomach or small intestine is quite different from sitting on the kitchen counter. I think this provides a great opportunity for students to critically evaluate an argument such as this and apply knowledge they’ve acquired.

Another issue here is the lack of a proper experiment. Simply holding up one McDonald’s burger doesn’t tell us much when we don’t have another burger to compare it to. Similarly, slices of raw potato don’t make a great control for a McDonald’s french fry longevity study aimed at demonstrating how un-foodlike McDonald’s products are. What would make a better control? What types of experiments could we design?

Today I stumbled across a blog post from J.Kenji-Lopez ( who seems to have taken issue with this pseudoscience of burger preservation and tried to approach it more scientifically. Read more about the experiments and analysis here. I like the comparison of % change in mass over time graph, interesting stuff.

This provocative video lecture, “Sugar: The Bitter Truth” by a scientist from UCSF argues that fructose is treated by our bodies as a poison and responsible for the modern obesity epidemic. Lots of great biochemistry too. This isn’t exactly a mainstream, FDA position, but that’s the point. How do we evaluate these types of claims? It gets even harder when it’s a scientist from a reputable university, and he’s using lots of formulas! How does the FDA make their guidelines? When you take a look at the obesity epidemic, obviously something about or recommendations isn’t working…

Another food related article illustrates the uncertainty in our scientific understanding of world. The headline ‘Twinkie diet helps nutrition professor lose 27 pounds” is definitely an attention grabber. There’s lots of room for questioning in here. Why do we eat the foods we do? A great food choice related infographic appeared in the NYTimes the other week highlighting ways we can subtly alter school cafeterias to increase positive choices. Reminded me of the book ‘Nudge’ a bit, but how do we know what is ‘good’?

Everyone is faced with food choices every day of their life. How can we better inform our choices? My students will soon be heading off to college and, for many of them, it will be the first time in their lives when they’re entirely responsible for what to eat. Yikes.

Michael Pollan has written extensively on food and nutrition and I really enjoy his perspective. His book, “In Defense of Food,” has a nice and simple message, “Eat food, mostly plants, not too much.” Word.


student skeptics

16 Aug

I recently received this email from a close relative who shall remain nameless:

Two moons on 27th August 2010
27th Aug the Whole World is waiting for………….

Planet Mars will be the brightest in the night sky starting August. It will look as large as the full moon to the naked eye. This will cultivate on Aug. 27 when Mars comes within 34.65M miles off earth. Be sure to watch the sky on Aug. 27 12:30 am. It will look like the earth has 2 moons.

Forwarding emails like this is basically the electronic version of regifting a crappy present. No one wants your label maker. This forward caught my eye though. Mars as big as the moon? Sounds fishy…Turning to a favorite website of mine for debunking silly email claims,,  my suspicions were confirmed, it was a hoax. In fact, as pointed out here, the picture isn’t even of our moon, but two moons of Saturn (see the rings at the bottom?)

Nonetheless, this got me thinking about the daily flood of “scientific” news, claims, and downright hoaxes. From the somewhat misleading claims of discovery of a  “____ (insert characteristic) gene,” to downright mischievous chain letters, sorting the good science from the bad can be quite a challenge.

I want to involve my students in the process of finding these questionable claims, and then working to validate/invalidate them. This presents a great opportunity to exercise the skill of evidence evaluation and critical thinking.

I recently came across Frank Noschese’s great physics blog Action-Reaction and his recent post on Physics Win? Fail? I love this idea and its right in line with what I’m imagining. This has got my gears spinning thinking of a comparable collection of biology fails. First to mind is all of the monster movies featuring creatures that push the limits of biomechanics (and physics…)

Checkout The Biology of B-movie monsters for a thorough and entertaining look at exactly that.

I welcome your suggestions for Biology Fails…

How do we know this? Encouraging skepticism

28 Jul

I want my students to challenge me. Allow me to explain. I’m not saying I want to throw down in an arm wresting contest or some other feat of strength.

Arm wrestling: Ok for settling child custody disputes, Not ok for classroom icebreaker

Better yet, I want my students to question the information that is being presented to them as “facts.” Let me clarify. I don’t want my students disrespectfully challenging my authority (not my idea of fun). I do want my students to be skeptical, to demand evidence, and to be able to evaluate ideas based on a rational, scientific way of thinking about the world (fun!).

To me, this is the single most important skill I can help ALL of my students develop. The phrase “critical thinking” is tossed around in school mission statements and ed philosophies more often than a sea lion pup at a killer whale party, but in this case its use is entirely justified. Many of my students won’t go on to become engineers or doctors or scientists, but every student, regardless of career choice, will be faced with lots of choices throughout their lives that require an ability to critically evaluate evidence in a logical and rational way.

Richard Dawkins has likened children to “information caterpillars,” gobbling up knowledge about their world unquestioningly [1]. This makes evolutionary sense; a young child inclined to test the validity of a parent’s rule, e.g. “don’t leave the cave after dark or bears will eat you,” probably won’t be celebrating too many birthdays.

information is yummy!

Of course, caterpillars have to become butterflies and adults shouldn’t believe in Santa Claus or fairies. Enter the teenager and the development of this way of thinking.

I envision two key parts (in the classroom anyways) to the development of a bullshit detector scientific skepticism

  • Understanding the process of science. I’m not talking PHEOC, I’m talking science as a way of thinking about the world. A non-linear process of making observations, asking questions, collecting and interpreting data, hypothesis testing and revision, etc. [2]
  • Applying this way of thought to real-world examples. After all, practice makes perfect.

One way I’m planning to emphasize this theme is a weekly ‘How do we know this?’ feature. In the spirit of acronyms (WCYDWT?) I’m inventing a new one: HDWKT. This is still a WIP, and as such, I haven’t figured out exactly what form(s) this will take in the classroom. Things it may include:

  • Background research by me ahead of time on to compile some key experiments, history, etc of how we know what we know about the topic(s) of that week
  • Students contributing to the background research
  • Analyzing and evaluating actual data from key experiments
  • Discussing/debating current issues (e.g. evolution/ID, GMOs/organic, natural resource conservation/consumption, global warming, etc)
  • Evaluating product claims (e.g. 8-minute abs (why not 7 minute abs?), 5-hour energy, weight loss pills, homeopathic medicine, etc) either experimentally or via research literature
  • Pseudoscience debunking

COMING SOON…HDWKT #1: The Age of the Earth

Some great resources for skepticism:

[1] “Unweaving the Rainbow” by Richard Dawkins – a great read!
[2] The website has some amazingly useful resources on the notion of “science as a process.” Full Disclosure: I will in no way benefit from you visiting the aforementioned website. On the other hand, your teaching probably will…
[3] Caterpillar image compliments of wikimedia commons. Baby image compliments of D Sharon Pruitt. Caterbaby hybrid compliments of Photoshop.