Fat vs. Carbohydrate Overeating: Which Causes More Fat Gain?

Two human studies, published in 1995 and 2000, tested the effect of carbohydrate vs. fat overfeeding on body fat gain in humans.  What did they find, and why is it important?

We know that daily calorie intake has increased the US, in parallel with the dramatic increase in body fatness.  These excess calories appear to have come from fat, carbohydrate, and protein all at the same time (although carbohydrate increased the most).  Since the increase in calories, carbohydrate, fat, and protein all happened at the same time, how do we know that the obesity epidemic was due to increased calorie intake and not just increased carbohydrate or fat intake?  If our calorie intake had increased solely by the addition of carbohydrate or fat, would we be in the midst of an obesity epidemic?

The best way to answer this question is to examine the controlled studies that have compared carbohydrate and fat overfeeding in humans.

Horton et al.

Garden Update: A Banner Year

Things are warming up here in Seattle and the flowers are blooming.  I just planted my first crops of the year-- potatoes and strawberries.

2013 was a banner year for my 500-square-foot urban vegetable garden, including my first experience growing and processing a grain.  I never got around to posting about it last year-- so here it is.

Interbay mulch technique

The bed on the right has been mulched with leaves, spent coffee
grounds, and burlap sacks ($1/sack at the local hardware store).
The beds on the left were planted with a rye-clover-vetch-pea
cover crop.  Paths are mulched with wood chips.

In the fall of 2012, I tried a new technique for improving the soil called "Interbay mulching".  This is a variation on sheet mulching, which involves placing uncomposted organic matter directly onto the garden soil in fall and letting it compost until the next growing season.  To Interbay mulch, you simply cover your sheet mulch with burlap.  This keeps everything moist, protects earthworms from bird predation so they can munch freely, and suppresses weeds.  I used leaves (carbon) and spent coffee grounds from a local coffee shop (nitrogen) for my organic matter.

When I pulled back the burlap last spring, I was initially disappointed.  The coffee grounds had disappeared completely, but there was still a lot of leaf matter left on the soil, indicating that it had only partially composted.  However, I later decided that it had worked well, because the soil structure underneath was improved and it seemed to be enriched with significant organic matter as well as a large population of fat earthworms.  The mulch suppressed weeds remarkably well, and the beds remained mostly clean for the rest of the season.

Those observations, combined with huge yields from the mulched beds, convinced me that it was worthwhile.

New tools

More Graphs of Calorie Intake vs. BMI

In the last post, a reader commented that the correlation would be more convincing if I graphed calories vs. average BMI rather than the prevalence of obesity.  It was a valid point, so I went searching for average BMI values from NHANES surveys.  I dug up a CDC document that contains data from surveys between 1960 and 2002 (1).  Because these data only cover five survey periods, we only get five data points to analyze, as opposed to the eight used in the last post.  The document contains BMI values for men and women separately, so I averaged the two to approximate average BMI in the general adult population.  It's also worth noting that I use the approximate midpoint of the survey period as the year.

First, a graph of average BMI over time.  It went up:

Now, let's see how well average BMI correlates with calorie intake:

The correlation between calorie intake and obesity prevalence was remarkable, but this correlation is simply incredible.  An R-squared value of 0.98 indicates that daily calorie intake and average BMI are almost perfectly correlated.

We can further deduce that each 100-calorie increase in daily food intake is associated with an 0.62-point increase in average BMI among US adults.  

Calorie Intake and the US Obesity Epidemic

Between 1960 and 2008, the prevalence of obesity in US adults increased from 13 to 34 percent, and the prevalence of extreme obesity increased from 0.9 to 6 percent (NHANES surveys).  This major shift in population fatness is called the "obesity epidemic".

What caused the obesity epidemic?  As I've noted in my writing and talks, the obesity epidemic was paralleled by an increase in daily calorie intake that was sufficiently large to fully account for it.  There are two main sources of data for US calorie intake.  The first is NHANES surveys conducted by the Centers for Disease Control.  They periodically collect data on food intake using questionnaires, and these surveys confirm that calorie intake has increased.  The problem with the NHANES food intake data is that they're self-reported and therefore subject to major reporting errors.  However, NHANES surveys provide the best quality (objectively measured) data on obesity prevalence since 1960, which we'll be using in this post.

Uncovering the True Health Costs of Excess Weight

Is excess weight hazardous to health, or can it actually be protective?  This question has provoked intense debate in the academic community, in some cases even leading researchers to angrily denounce the work of others (1).  There is good evidence to suggest that excess body fat increases the risk of specific diseases, including many of our major killers: diabetes, heart attack, stroke, heart failure, cancer, and kidney failure (2).  Yet strangely, the studies relating excess weight to the total risk of dying-- an overall measure of health that's hard to argue with-- are inconsistent.  Why?

New Position with Nestlé

Warning -- Satire -- April Fool's Post

I'm happy to announce that I've accepted a Product Research and Development position with Nestlé Foods.  Nestlé is known for its skillful application of 'neuromarketing'-- using neuroscience to enhance product development and sales-- and the company recruited me for my background in neuroscience and food reward.

As Whole Health Source readers know well, food reward has a major impact on food selection and consumption, and therefore it has huge potential as a product development strategy.  Although product development by the food industry has always relied to some extent on a basic understanding of food reward, corporations still lag far behind the cutting edge of food reward research, and they are therefore missing out on a major opportunity to drive repeat purchase and consumption behavior and increase total sale volume.  I plan to leverage science-corporate synergy to develop food product solutions that people LOVE*.

Even more exciting, Nestlé has asked me to lead a strategic partnership initiative with Coca-Cola to utilize neuromarketing to tailor beverage product development specifically for children, who have a somewhat different set of reward criteria than adults.  We're excited to develop product solutions that kids LOVE* even more than current offerings, by scientifically designing new combinations of flavors, sweeteners, and totally safe habit-forming drugs such as caffeine.

Both companies have been very responsive to my nutritional concerns about processed foods, and so we're working together to make healthier products.  Here are some of the changes we're discussing:

• Adding vitamin C and cod liver oil to chocolate.
• Replacing a portion (1.7%) of the sugar in beverages with stevia across the board.
• Stealthily decreasing the portion size of beverages.  To do this, we'll increase the thickness of the plastic bottles so the exterior of the bottle is the same size, but the actual beverage content is reduced by 0.2 oz.
• Getting these healthy snacks and beverages back into schools where kids can enjoy them!

One of the first things we discussed is getting the advertising department at Nestlé to write guest posts for Whole Health Source.  This will be a fun way for WHS readers to stay informed of current Nestlé products and what we have coming down the pipeline!

April Fools!!!!!!


* Learned Obedience Via Eating