Sunday, November 22, 2015

Fat, Added Fat, and Obesity in America

In the last post, we saw that carbohydrate and particularly sugar intake have been declining in the US since 1999, even as our obesity rate has continued to climb.

In this post, let's look at another putative driver of obesity: our fat intake, and especially our intake of added fats like seed oils, butter, and olive oil.  Like the graphs in the last post, the data underlying the following graphs come from USDA food disappearance records (not self-reported), and NHANES survey data (1, 2).  Also like the last post, the graph of total fat intake is not adjusted for waste (non-eaten food), while the graph of added fat intake is*.  As a consequence, the figures for total carbohydrate and total fat intake are higher than actual intakes, but still good for illustrating trends.

Here we go.  First, total fat:

Monday, November 16, 2015

Carbohydrate, Sugar, and Obesity in America

We like explanations that are simple, easy to understand, and explain everything.  One example of this is the idea that eating carbohydrate, or sugar, is the primary cause of obesity.  This lets us point our finger at something concrete and change our behavior accordingly.  And it's true enough that it has practical value.  But the world around us often turns out to be more complex than we'd like it to be.

The CDC recently released its latest data on the prevalence of obesity in the US, spanning the years 2013-2014 (1).  These data come from its periodic National Health and Nutrition Examination Surveys (NHANES).  Contrary to what many of us had hoped for after a slight decline in obesity in the last survey, the prevalence has once again increased.  Today, roughly 38 percent of US adults have obesity.  As a nation, we're continuing to gain fat, which is extremely concerning.

I decided to examine the relationship between obesity prevalence and our intake of carbohydrate and sugar over the years.  The food intake data come from the USDA's Economic Research Service (2).  For some reason, the data on carbohydrate don't extend beyond 2010.  This probably relates to funding cuts at the USDA*.

Let's have a look at the data for carbohydrate:

Friday, October 30, 2015

Monday, October 26, 2015

Do Processed and Red Meat Cause Cancer?

Today, the World Health Organization's International Agency for Research on Cancer published a statement in The Lancet detailing its position on the carcinogenicity of processed and red meat (1).  The statement, resulting from a meeting of 22 scientists from 10 countries, concluded that processed meat is a group 1 carcinogen, meaning that it is "definitely carcinogenic to humans".  They also judged that red meat is a group 2A carcinogen, meaning that it probably causes cancer but the evidence isn't as strong.  They're mostly referring to the links between processed and red meat and digestive tract cancer, particularly cancers of the colon and rectum.

These statements were met with a media frenzy, and the expected furor from the meat industry.  The most surprising thing, for me, is that anyone would be surprised by the IARC's statement.

Friday, October 16, 2015

Why Do Girls and Boys Reach Puberty Younger Than They Used To?

Girls, and probably boys, are reaching puberty years younger than they did in our great-grandparents' generation.  Why?  There's no shortage of explanations, but the primary reason is probably quite simple.

Thursday, October 8, 2015

Will You Fill Out This Paleo Diet Survey?

This week, I received an e-mail from a graduate student at Humboldt State University named May PatiƱo.  She asked me to share her online research survey targeted to Paleo dieters.  Here are the goals of her research, in her words:
The main objective of my study is exploring how the Paleo diet is being implemented in practice.  I would like to assess the health outcomes of these practices, as well evaluate how closely they conform to, or deviate from ways this diet is being described in theoretical literature, and implemented in controlled diet trials. I also want to be able to use the data collected to help explain what is driving the popularity of the ancestral health movement. Ultimately, I would like this information to be used to better inform protocols for controlled diet trails.
The survey took me about 40 minutes to complete.  You're welcome to participate whether or not you're on the Paleo diet.  Please consider taking the survey, for the love of science!

Research Survey: The Paleo Diet in the US

Monday, October 5, 2015

That Time I Ate Most of a Large Pizza in One Sitting

Two weeks ago, I had a brush with Extreme Eating.  My experience illustrates some important principles of how the brain regulates appetite and body fatness-- and how it reacts to calorie-dense, highly rewarding foods.