This Friday it once again became clear how far I’m removed from the cutting edge of science. That is, if the cutting edge is a crapfest in experimental design.
More Fun With Science
When scientists, I mean, real and supposedly serious scientists flat-out proclaim that “chocolate is not fattening,” it makes everyone’s ears prick up.
When they even go as far as saying that consumption of chocolate is independent of physical activity and diet, then that’s like proclaiming Newton was wrong and you got the floating apple to show it.
But let’s start at the beginning. Scientists from the University of Granada took a bunch of teens and, in their own words, did the following:
This study comprised 1458 adolescents (ages 12.5–17.5 y) participating in HELENA-CSS (Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study). Dietary intake was self-registered using a computer-based tool for 24-h dietary recall on 2 non-consecutive days. Weight and height were measured, and BMI was calculated. Adiposity was estimated using skinfolds (Slaughter’s equation) and bioelectrical impedance analysis (BIA). Waist circumference was measured.
Ok, you have 1,458 participants, measure their bodies and then ask them what they ate a day before via a computer program. To say you got meaningful data out of this you need to assume:
- the teens answered truthfully
- they remembered everything they ate
- what they ate on those two days is representative of their diets
Can you remember everything you ate yesterday? Or would you change your eating habits for two days, knowing you have to answer questions about them?
Me at least it would take a food journal that I update right on the spot to be precise about it. I also can’t say how teen me would have handled “nothing but the truth” when “old people” (those over twenty) asked me about my chocolate eating habits.
The Sexy Headline
But whatever, it was the basis for everything that is to come. Unfortunately the paper is not available for free, so I give you a rundown.
They calculated average chocolate intake in grams per day and found that the biggest average consumption was 42.6 g / day, the lowest 4.7 g. The teens in the highest consumption group had higher saturated fat and energy intake than those in the lowest, but also had higher rates of physical activity and lower measures of fatness. Statistically analysing this, the researchers found that as chocolate consumption increased, body fat decreased.
So what they really got was that teens who eat more chocolate are more physically active, but what they reported in their press release was this:
Scientists at the University of Granada have disproved the old idea that chocolate is fattening, in a study reported this week in Nutrition. Higher chocolate consumption associated with lower levels of total fat—fat deposits all over the body—and central—abdominal—fat, independently of whether or not subjects are physically active, and of their diet.
As for the how they suppose that happens, they don’t really have any idea beyond mumbling a bit about “catechins.”
It Proves Nothing
Could there be a connection? Yes, but proving it requires doing some research where what participants eat is fully controlled. All the studies mentioning a “chocolate lovers are thinner” connection so far, including this one, viciously suffer from self-reporting the scientists have no control over.
But those previous papers at least acknowledged their limitations and didn’t go out and call their crap research on the subject “the largest and best-controlled study to date.”
Picture courtesy of “everjean“.