Thursday, June 9, 2016

A Serious Challenge to the 2012 Low-carbohydrate "Metabolic Advantage" Study

Warning: this post will be a bit more wonkish than usual, because I need to get detailed to make my points.  To read a summary, skip to the end.

In 2012, David Ludwig's group published an interesting RCT that suggested a substantial "metabolic advantage" resulting from a high-protein, very-low-carbohydrate diet (VLC) (1).  In other words, this diet led to a higher energy expenditure relative to a normal-protein, low-fat diet (LF) over a one month period (a low-glycemic-load, normal-protein diet was in the middle and not significantly different from the other two).  Resting energy expenditure (REE) was slightly but significantly higher on the VLC diet, and total energy expenditure (TEE) was elevated by a whopping 300+ kcal/day!  I covered the study at the time, describing it as "fascinating" and "groundbreaking", and calling for the study to be replicated so we can be more confident in its unexpected result (2).

This finding has been used by Ludwig, Gary Taubes, and others to support the carbohydrate-insulin hypothesis of obesity, although there is no evidence that the effect was mediated by insulin, and also no evidence that it was mediated by reduced carbohydrate rather than increased protein (3).

Since I published that post, my confidence in the finding-- and particularly the common interpretation of it that reducing carbohydrate intake to a very low level increases REE and TEE-- has gradually been eroding.  This is partially because other studies have generally reported that the carbohydrate:fat ratio of the diet has little or no effect on REE, TEE, or fat storage (4, 5, 6, 7, 8, 9, 10).

Tuesday, May 10, 2016

Why some dogs (and humans) are born hungry

The brain is the central regulator of appetite and body fatness, and genetic variation that affects body fatness tends to act in the brain.  One important site of variation is the POMC gene, which codes for a signaling molecule that suppresses food intake.  A new study shows that Labrador retrievers often carry an inactive version of the POMC gene, causing them to be highly food motivated, obesity-prone-- and perhaps more easily trainable. 

Wednesday, May 4, 2016

My Recent Paper on Linoleic Acid in Adipose Tissue

Linoleic acid (LA) is the predominant polyunsaturated fat in the human diet, and it's most concentrated in seed oils such as corn oil.  LA accumulates in fat tissue, and as with many of the nutrients we eat, it is biologically active.  In a new paper, we systematically review the studies that have measured the LA concentration of fat tissue in US adults over time.  We show that the LA concentration of fat tissue has increased by approximately 136 percent over the last half century.

Susan Carlson, PhD
In 2011, I posted a graph on my blog in which I summarized some of the studies that have measured the LA content of fat tissue in US adults over time (1).  It showed a remarkably consistent upward trend.  Last year, a University of Kansas nutrition researcher named Susan Carlson contacted me and asked if I had published my findings in a scientific journal, because she wanted to cite the trend in one of her papers.  I said I hadn't published them, but that I would love to do so together.

Friday, April 1, 2016

Invincible Coffee: The Next Evolution of Joe

Warning -- Satire -- old April Fools post!

You've heard of Bulletproof Coffee, that mixture of coffee and butter that keeps you lean and supercharges your mental focus.

The problem with Bulletproof Coffee is that the butter forms a greasy oil slick on top of your coffee.  Yuck!  Is there any way to rescue Bulletproof Coffee?


Enter Invincible Coffee, the next evolution of Joe.

Thursday, March 24, 2016

Can Salt Increase Calorie Intake?

The debate rages on over whether dietary salt (NaCl) increases the risk of cardiovascular events, with no clear answer in sight.  Yet few people are paying attention to another, more insidious effect of salt: it may increase our calorie intake, and eventually, the size of our waistlines.

Introduction

Humans are born with specific hard-wired food motivations, which guide us to food properties that kept our ancestors alive and fertile in times past.  We have an instinctive attraction to sweetness because, in the world of our ancestors, it indicated ripe fruit or honey-- both important sources of calories and other nutrients.  Most of the other food properties we're instinctively drawn to, such as starch, fat, and glutamate, signify high-calorie foods.

Yet one of our hard-wired food motivations stands out from the rest: our attraction to salt.  Since salt is calorie-free, salt appetite is one of the few instinctive food drives that doesn't relate directly to acquiring calories.  Interestingly, salt is the only essential micronutrient (vitamin/mineral) we can taste at the concentrations normally found in food.  Not only our brains, but also our tongues, are hard-wired to seek salt above all other micronutrients.

Tuesday, March 15, 2016

A Free Issue of Examine.com Research Digest

Examine.com is a website that provides unbiased information on supplements and nutrition.  They publish the Examine.com Research Digest (ERD), which reviews the latest studies in these areas.  I like ERD because it does a nice job of curating recent science, making it understandable and engaging for a broad audience, and explaining important background information.  They have no conflicts of interest because they don't sell anything except information.  I've been a scientific reviewer for ERD since the beginning.

Examine.com is celebrating its fifth anniversary today.  To celebrate, they offered to put together a custom issue of ERD using five of my favorite articles.  I chose articles I thought my audience would enjoy.  You can download your free copy here (PDF).

If you like it and decide you want to sign up for ERD, there is a link in the PDF, or you can visit this page.  They're having a sale today, so if you're thinking about joining, today is a good choice.  If you purchase through the links I provided, you'll be supporting Whole Health Source at no extra cost to yourself.

If you already have ERD, let me know how you like it in the comments.

Wednesday, February 17, 2016

What I Eat

People often ask me what I eat.  I've been reluctant to share, because it feels egocentric and I'm a private person by nature.  I also don't want people to view my diet as a universal prescription for others.  But in the end, as someone who shares my opinions about nutrition, it's only fair that I answer the question.  So here we go.

In my food choices, I try to strike a balance between nutrition, cost, time efficiency, animal welfare, pleasure, and environmental impact.  I'm the chef of my household of two, and I cook two meals a day, almost every day, typically from single ingredients.  I prefer organic, but I don't insist on it.

Eggs from my hens
My diet changes seasonally because I grow much of my own food.  This started out with vegetables, but recently has expanded to staple foods such as potatoes, flour corn, and winter squash.  I also have a small flock of laying hens that turn table scraps, bugs, grass, and chicken feed into delicious eggs.

The primary guiding principle of my diet is to eat somewhere between a "Paleolithic"-style diet and a traditional agricultural/horticultural diet.  I think of it as a broad ancestral diet.  Because it's partially inspired by agricultural/horticultural diets, starch is the main calorie source.

My meals are organized around three food groups: a protein, a starch, and vegetables/fruit.  If any of those three are missing, the meal doesn't feel complete.  I'll start with those categories and move on from there.