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On Set Point and Carbohydrate Requirements

July 26, 2011

A while back, I wrote a post about set points and what I was calling “settling points.” Since then, I’ve learned a lot about set points (mostly from Stephan’s amazing series on food reward and obesity) and I’ve come to believe that what I wrote really missed the definition of “set point.” Live and learn.

Contrary to the way many people use the term, a set point is not a permanent feature of a person. The set point is, instead, the fat mass one’s body is aiming to achieve at any given time. I’ll get into how to manipulate your set point in much more detail in a later post – for now let’s just assume that you can.

A quick review: If your set point is lower than your current body fat, you’re body will attempt to force fat loss with neat tricks like appetite suppression and increased energy expenditure. If your set point is higher than your current body fat, you’ll be extra hungry and your body will strive to reduce expenditure until your body fat reaches your set point. Obviously, if your body fat and set point are the same, your body will do its best to maintain equilibrium.

This summer, I’ve found my carbohydrate requirement to be much higher than it has been since “going paleo,” and I think my set point has a lot to do with it. The logic behind my thinking is relatively straightforward, but it requires an understanding of one last insanely intriguing aspect of the set point theory of body fat regulation.

The rate at which you burn fat is directly related to amount by which your set point is below your current body fat mass. In other words, the fat burning rate is dependent upon the difference between the current set point and current fat mass. To make this clear, let’s look at two dieters. Fatter dieter is carrying 50 lbs of fat and, through manipulation of his diet, his set point is 20 lbs. Thinner dieter is carrying 30 lbs and his set point is also 20 lbs. Fatter dieter will lose fat at a faster rate than thinner dieter because he is further from his set point, through a variety of mechanisms. His resting energy expenditure will increase more (he’ll run hotter and fidget more) and his appetite will be suppressed to a greater extent than that of his thinner counterpart. Here’s the jump I’m asking you to make: I believe his body will derive a higher proportion of its energy requirement from fat than thinner dieter’s will. In other words, his body will be more willing to work in the beta-oxidative pathway.

Okay now back to me. My body fat mass is arguably lower than it has ever been right now. I think I’m around 8%, which would mean I’m carrying roughly 13.5lbs of fat. It’s hard to believe that my set point is much below that, given my current diet. If my set point and fat mass are close together, the above reasoning indicates that my body is less willing to burn fat for energy. Since I still need energy, this means that my body prefers to run in the glycolytic pathway – use sugar for energy. Ironically, my high-fat, low-carb diet has made me a carb burner (through fat loss).

I can hear the alarm bells sounding in your collective head. Fear not, dear friends, I’m still not eating much carbohydrate by USDA standards. My daily carb intake is up from around 20-40 g/day (with the exception of my leangains experiment) to 120-200 g/day on average. Considering that my total intake is hovering (by rough estimate) in the 2700-3400 cals/day, my carbohydrate intake is only 15-30% of calories.

One could also make the argument that my carbohydrate intake has increased simply because I’m exercising more and eating more – I’ve merely laid out a possible mechanism for my perceived increased need for carbohydrate. Also, I’ve noticed that long bouts of high intensity intervals (pick-up hockey) now demand more carbohydrate intake than they used to, which I’ve taken as a sign that I’m not burning fat as readily as I was a few months ago. Food for thought.

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