Last week, the New England Journal of Medicine published an interesting editorial titled "Candy at the Cash Register-- a Risk Factor for Obesity and Chronic Disease." This fits in well with our discussion of non-homeostatic eating, or eating in the absence of calorie need.
There are a few quotes in this article that I find really perceptive.
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Saturday, October 20, 2012
Wednesday, October 17, 2012
Saturday, October 13, 2012
Why Do We Eat? A Neurobiological Perspective. Part II
In the last post, I explained that eating behavior is determined by a variety of factors, including hunger and a number of others that I'll gradually explore as we make our way through the series. These factors are recognized by specialized brain 'modules' and forwarded to a central action selection system in the midbrain (the reward system), which determines if they are collectively sufficient cause for action. If so, they're forwarded to brain systems that directly drive the physical movements involved in seeking and consuming food (motor systems).
The term 'homeostasis' is important in biology. Homeostasis is a process that attempts to keep a particular factor within a certain stable range. The thermostat in your house is an example of a homeostatic system. It reacts to upward or downward changes in a manner that keeps temperature in a comfortable range. The human body also contains a thermostat that keeps internal temperature close to 98.6 F. Many things are homeostatically regulated by the body, and one of them is energy status (how much energy the body has available for use). Homeostasis of large-scale processes in the body is typically regulated by the brain.
We can divide the factors that determine feeding behavior into two categories, homeostatic and non-homeostatic. Homeostatic eating is when food intake is driven by a true energy need, as perceived by the brain. For the most part, this is eating in response to hunger. Non-homeostatic eating is when food intake is driven by factors other than energy need, such as palatability, habitual meal time, and food cues (e.g. you just walked by a vending machine full of Flamin' Hot Cheetos).
We can divide energy homeostasis into two sub-categories: 1) the system that regulates short-term, meal-to-meal calorie intake, and 2) the system that regulates fat mass, the long-term energy reserve of the human body. In this post, I'll give an overview of the process that regulates energy homeostasis on a short-term, meal-to-meal basis.
The Satiety System (Short-Term Energy Homeostasis)
The stomach of an adult human has a capacity of 2-4 liters. In practice, people rarely eat that volume of food. In fact, most of us feel completely stuffed long before we've reached full stomach capacity. Why?
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The term 'homeostasis' is important in biology. Homeostasis is a process that attempts to keep a particular factor within a certain stable range. The thermostat in your house is an example of a homeostatic system. It reacts to upward or downward changes in a manner that keeps temperature in a comfortable range. The human body also contains a thermostat that keeps internal temperature close to 98.6 F. Many things are homeostatically regulated by the body, and one of them is energy status (how much energy the body has available for use). Homeostasis of large-scale processes in the body is typically regulated by the brain.
We can divide the factors that determine feeding behavior into two categories, homeostatic and non-homeostatic. Homeostatic eating is when food intake is driven by a true energy need, as perceived by the brain. For the most part, this is eating in response to hunger. Non-homeostatic eating is when food intake is driven by factors other than energy need, such as palatability, habitual meal time, and food cues (e.g. you just walked by a vending machine full of Flamin' Hot Cheetos).
We can divide energy homeostasis into two sub-categories: 1) the system that regulates short-term, meal-to-meal calorie intake, and 2) the system that regulates fat mass, the long-term energy reserve of the human body. In this post, I'll give an overview of the process that regulates energy homeostasis on a short-term, meal-to-meal basis.
The Satiety System (Short-Term Energy Homeostasis)
The stomach of an adult human has a capacity of 2-4 liters. In practice, people rarely eat that volume of food. In fact, most of us feel completely stuffed long before we've reached full stomach capacity. Why?
Read more »
Thursday, October 4, 2012
Photos and More Gardening
I've needed new professional and blog photos for a long time. My friend Adam Roe was in town recently, and he happens to be professional photographer, so he graciously offered to snap a few shots. Despite less than ideal conditions, he did an outstanding job. Here's a larger version of the photo on my profile (which Blogger shrinks down to a tiny thumbnail):
To see more of Adam's work, head over to his Facebook page, and don't forget to 'like' and share it if you enjoy it. Adam is currently based in Berlin.
Gardening Update
Here's a photo of today's harvest (taken by me, not Adam; you can tell by the poor focus and primitive lighting):
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To see more of Adam's work, head over to his Facebook page, and don't forget to 'like' and share it if you enjoy it. Adam is currently based in Berlin.
Gardening Update
Here's a photo of today's harvest (taken by me, not Adam; you can tell by the poor focus and primitive lighting):
Read more »
Monday, October 1, 2012
Why Do We Eat? A Neurobiological Perspective. Part I
As with all voluntary movements, eating food is an expression of activity in the brain. The brain integrates various inputs from around the body, and outside the body, and decides whether or not to execute the goal-directed behaviors of food seeking and consumption. Research has uncovered a lot about how this process works, and in this series I'll give a simplified overview of what scientists have learned about how, and why, the brain decides to eat.
The Gatekeeper of Voluntary Behaviors
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The Gatekeeper of Voluntary Behaviors
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Friday, September 14, 2012
More Thoughts on Macronutrient Trends
I had a brief positive exchange with Gary Taubes about the NuSI post. He reminded me that there's an artifact (measurement error) in the USDA data on fat consumption in the year 2000 when they changed assessment methods. Here are the USDA data on macronutrient consumption since 1970, corrected for loss (28.8%) but not corrected for the artifact:
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Wednesday, September 12, 2012
Nutrition Science Initiative (NuSI)
Some of you may have heard of an ambitious new nutrition research foundation called the Nutrition Science Initiative (NuSI). In this post, I'll explain what it is, why it matters, and how I feel about it-- from the perspective of an obesity researcher.
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