metabolic-pathways – Justin Owings

I cite Seth Roberts’ blog a great deal over at Linked Down. Seth is a Psychology Professor at Berkeley and an avid self-experimenter. I’ve learned a great deal from subscribing to his blog.

For those who don’t know, Seth Roberts created the Shangri-La Diet, which is a diet centered around reducing the association between flavor and caloric load. I haven’t read the book, so this is an approximation of how it works, but the gist is that the more correlated taste is to caloric load, the greater hunger can be, the harder it will be to cut calories, and the higher your body’s set point for weight will be. “SLD” hacks this relationship via ingesting flavorless calories within certain windows of time. These flavorless calories reduce the brain’s association of high energy density and high flavor. Interestingly enough, the macronutrient source of the calories may be unimportant: you can do SLD with oil, sugar water (so long as it is flavorless), or nose-clipping while eating protein. If you’re skeptical about this diet, I suggest taking a trip over to the SLD Forums and be prepared to see plenty of evidence that SLD works.

Even as I have not tried SLD, it is a fascinating idea and it seems that anyone who is serious about better understanding why we gain weight and what regulates hunger and adiposity must take it seriously enough to figure out how it fits into the big picture of human health. Barring that gargantuan task, it’s at a minimum another way to try and hack weight loss if your current regiment isn’t cutting it for you.

I mention all of this because I stumbled on a 2008 interview between Roberts and Gary Taubes, author of Good Calories, Bad Calories, which I’ve blogged about exhaustively. What a great thing to find that two people I admire had a thoughtful discussion and, even better, said discussion has been made available to me?

Blogging, science and the internet FTW.

Back to trying to understand how SLD fits into the grand scheme of human physiology. An interesting comment was made at the bottom of Part 13 of Roberts’ Interview of Gary Taubes:

I’ve thought a lot about how consuming tasteless food could supress hunger. My favorite theory is that it is similar to what happens when an animal is hibernating. The “magical” appearance of calories fools your body into thinking it is living off its fat and then it actually does so.

This comment reminded me of how the metabolic pathways while fasted are the same as when we consume a diet of only fat and protein. One effect of low-carb diets is appetite suppression. Could the common theme here simply be that both SLD and low-carbohydrate diets and/or fasting act to “trick” our bodies into switching to a non-hungry state?

Obviously that can’t be the entire picture because insulin is the storage hormone that is unleashed by carbohydrate consumption (though less so with fructose).

This issue is worthy of further thought.

Was just commenting on Patri Friedman’s livejournal (here) regarding how the metabolic channels used while fasting were the same as those used while on a low-carb diet. Taubes notes fact in passing in Good Calories, Bad Calories but since that’s a hard reference to check on the ‘net, here’s another bit of support from Dr. Mike Eades of Protein Power:

If you read any medical school biochemistry textbook, you’ll find a section devoted to what happens metabolically during starvation. If you read these sections with a knowing eye, you’ll realize that everything discussed as happening during starvation happens during carbohydrate restriction as well. There have been a few papers published recently showing the same thing: the metabolism of carb restriction = the metabolism of starvation. I would maintain, however, based on my study of the Paleolithic diet that starvation and carb restriction are simply the polar ends of a continuum, and that carb restriction was the norm for most of our existence as upright walking beings on this planet, making the metabolism of what biochemistry textbook authors call starvation the ‘normal’ metabolism.

As noted before, this makes intuitive sense. While in a fasted state, the body gets its energy fix by robbing the protein for gluconeogenesis from lean tissue and the fat for energy from adipose tissue. While doing low-carb, the body does the same thing — the only difference is that it gets the fat and protein from dietary sources.

The rest of the Eades article discusses ketones/ketosis, which I’m still working on fully understanding (the basics, anyway). Apparently there are other benefits to occasionally being in a ketogenic state that may include “de-junking” our cells. Neat!