Wednesday, February 27, 2013

Your Brain on Potato Chips

Or, more accurately, a rat's brain on potato chips.  Last week, PLoS One published a very interesting paper by Dr. Tobias Hoch and colleagues on what happens in a rat's brain when it is exposed to a highly palatable/rewarding food (1).  Rats, like humans, overconsume highly palatable foods even when they're sated on less palatable foods (2), and feeding rats a variety of palatable human junk foods is one of the most effective ways to fatten them (3).  Since the brain directs all behaviors, food consumption is an expression of brain activity patterns.  So what is the brain activity pattern that leads to the overconsumption of a highly palatable and rewarding food?

Monday, February 25, 2013

Salt Sugar Fat

I'd just like to put in a quick word for a book that will be released tomorrow, titled Salt Sugar Fat: How the Food Giants Hooked Us, by Pulitzer prize-winning author Michael Moss.  This is along the same lines as Dr. David Kessler's book The End of Overeating, which explains how the food industry uses food reward, palatability, and food cues to maximize sales-- and as an unintended side effect, maximize our waistlines.   Judging by Moss's recent article in New York Times Magazine, which I highly recommend reading, the book will be excellent.  I've pre-ordered it.

Friday, February 22, 2013

Food Reward Friday

This week, Food Reward Friday is going to be a little bit different.  I've received a few e-mails from people who would like to see me write about some of the less obvious examples of food reward-- foods that are less extreme, but much more common, and that nevertheless promote overeating.  Let's face it, even though they're funny and they (sometimes) illustrate the principle, most people reading this blog don't eat banana splits very often, much less pizzas made out of hot dogs.

So this week's "winner" is something many of you have in your houses right now, and which was also the subject of an interesting recent study... potato chips!

Tuesday, February 19, 2013

Body Fatness and Cardiovascular Risk Factors

I recently revisited a really cool paper published in the Lancet in 2009 on body fatness, biomarkers, health, and mortality (1). It's a meta-analysis that compiled body mass index (BMI) data from nearly 900,000 individual people, and related it to circulating lipids and various health outcomes.  This is one of the most authoritative papers on the subject.

Friday, February 8, 2013

Food Reward Friday

This week's lucky "winner"... an unnamed hot dog-laden Pizza Hut monstrosity with tempura shrimp and mayonnaise!

Tuesday, February 5, 2013

Why Do We Eat? A Neurobiological Perspective. Part VIII

In the (probably) last post of this series, I'll take the pieces that I've gradually outlined in previous posts, and put them together into a big-picture, common-sense framework for thinking about human eating behavior, and why we eat more today than ever before.

Why is Eating Behavior Regulated?

Let's start at the most fundamental level.  To be competitive in a natural environment, organisms must find rational ways of interacting with their surroundings to promote survival and reproduction.  One of the most important elements of survival is the acquisition of energy and chemical building blocks, either by photosynthesis, or (in the case of animals) eating other organisms.  This imperative drove the evolution of rational food seeking behaviors long before the emergence of humans, mammals, reptiles, amphibians, fish, worms, and even eukaryotes (organisms with nuclei).

Monday, February 4, 2013

Why Do We Eat? A Neurobiological Perspective. Part VII

Welcome back to the series, after a bit of a hiatus!  In previous posts, we covered the fact that humans eat because we're motivated to eat, and many things can motivate us to eat.  These include factors related to energy need (homeostatic factors), such as hunger, and factors that have little to do with energy need or hunger (non-homeostatic factors).  These many factors are all processed in specialized brain 'modules' that ultimately converge on a central action selection system (part of the reward system); this is the part of you that decides whether or not to initiate eating behaviors.

This will be somewhat of a catch-all post in which I discuss cognitive, emotional, and habit influences on food intake.  Since these factors are not my specialty, I'll keep it brief, but I don't mean to suggest they aren't important.

Food 'Cost'

Sunday, February 3, 2013

Why Do We Eat? A Neurobiological Perspective. Part VI

In previous posts in this series, I explained that the brain (primarily the mesolimbic system) integrates various factors to decide whether or not to drive food seeking and consumption behaviors.  These include homeostatic factors such as hunger, and non-homeostatic factors such as palatability and the social environment.

In this post, I'll examine the reward system more closely.  This is the system that governs the motivation for food, and behavioral reinforcement (a form of learning).  It does this by receiving information from other parts of the brain that it uses to determine if it's appropriate to drive (motivate) food seeking behavior.  I covered its role in motivation in the first post of the series, so in this post I'll address reinforcement.

Behavioral Reinforcement

Saturday, February 2, 2013

Why Do We Eat? A Neurobiological Perspective. Part V

In previous posts, I explained that food intake is determined by a variety of factors that are detected by the brain, and integrated by circuits in the mesolimbic system to determine the overall motivation to eat.  These factors include 'homeostatic factors' that reflect a true energy need by the body, and 'non-homeostatic factors' that are independent of the body's energy needs (e.g. palatability, habit, and the social environment).

In this post, we'll explore the hedonic system, which governs pleasure.  This includes the pleasure associated with food, called palatability.  The palatability of food is one of the factors that determines food intake.

The Hedonic System

Friday, February 1, 2013

Why Do We Eat? A Neurobiological Perspective. Part IV

In this post, I'll follow up on the last post with a discussion two more important factors that can affect energy homeostasis and therefore our food intake and propensity to gain fat: age and menopause.


Although it often isn't the case in non-industrial cultures, in affluent nations most people gain fat with age.  This fat gain continues until old age, when many people once again lose fat.  This is probably related to a number of factors, three of which I'll discuss.  The first is that we tend to become less physically active with age.  The second, related factor is that we lose lean mass with age, and so energy expenditure declines.