So there I was on the forums of t-nation.com answering questions about my recent interview piece with Gary Taubes when I started to wonder if this low-carb thing was legitimate after all.  “Have I been giving bad advice the whole time?  Should I just be telling people to ‘eat less and exercise more?’  But that’s never worked…  What I do now works like clock work… But all these posts keep telling me how ‘retarded’ me and Gary are…’”, I worried to myself.

What’s not authoritative and intimidating about being insulted over and over again by anonymous people on a forum?  If they can type it on a forum it must be well researched and true!  Right?

I did come to my thin-skinned senses eventually, BUT the folks on the t-nation forums did leave me with one question that I wasn’t entirely sure about:  Is ASP the overlooked flaw in low-carb dieting?

There were a lot of posts saying in effect: “What Tuabes and the rest of the low-carb community don’t like talking about is a little compound called acylation stimulating protein (ASP) which stores dietary fat in the fat cell with ZERO rise in insulin levels.”

I started doing some digging and found statements like these in peer reviewed research (I’m paraphrasing to make them readable and concise):

#1.  “ASP is far more powerful than insulin in stimulating the creation of new body-fat.” (1)

#2.  “ASP is released in response to an oral fat load.” (2)

Did I Get Served On A Forum?

I started really getting into ASP research at about 10pm on a Saturday night, and by the time I found the above statements in peer reviewed research I started sweating and my stomach was twisted up in knots.  I tried to let it go and hang out with my fiancé, but I just had to know – “What’s the deal with ASP!?  Is this something the debunks low-carb?”

So I spent the next 6 hours combing everything that I could get my hands on about ASP, and every time a paper made on of the above statements (#1 & 2 above) I noted the paper they cited.  (By the way, my biochemistry textbooks were no help at all.)  Pretty soon it became clear that those two statements were pretty much built off of two papers published in 1989:

•    Statement #1 above was pretty much built off of a paper titled “Purification and characterization of acylation stimulating protein”, but let’s call it “ASP trumps insulin” for this article.

•    Statement #2 above was built off of a paper titled “Metabolic response of acylation stimulating protein to an oral fat load,” but let’s call it “ASP is released in response to fat, not carbs.”

Does ASP Trump Insulin?

For the “ASP trumps insulin paper” the researchers grew fat cells in cultures (outside the body).  It is true the addition of ASP REALLY accelerated the creation of new fat (triglyceride) – it was faster than insulin.

HOWEVER, both the ASP and the no-ASP cultures had insulin and carbs added to them.  So the water is very muddy:

Could the ASP be a way in which insulin accelerates its activity?  Maybe the super deadly combo a high-fat and high sugar meal?  Maybe the only thing to learn from this study is that frosting is more fattening than candy?  Why not test ASP without insulin and carbs if your goal is to see what the difference between them is?

Or, for that matter, why not just test ASP in actual people instead of cultures? (1)

Is ASP Released In Response to Fat, Not Carbs?

For the “ASP is released in response to fat, not carbs.” The “lipid meal” or “oral fat load” that was used to induce the ASP response was cream + one tbsp table sugar (sucrose) + one tbsp nonfat dry milk.

That mixture is 25% carbs by weight!  So, that really doesn’t tell us anything at all.

Why not just have people drink olive oil or melted butter instead of cream plus a bunch of sugary stuff?

Take It Home Gary

I shared my research with Gary Taubes and he had this to say:

Gary and his cat

“Nice to know you’re suitably obsessed Josef.

“One thing to keep in mind in all this is the need to explain the observations, not just work with possible mechanisms that can’t explain anything. So one of the observations is weight loss on a high fat diet — the Atkins diet.

“So if ASP was good at sequestering dietary fat away in the fat tissue without carbs being needed, why would people lose weight when they ate an Atkins diet?

“Another observation we’re trying to understand, as I point out in lectures, is the obesity in poor populations eating low-fat, high carb diets. So there ASP would be irrelevant. Now if we had obesity in populations eating low-carb, high-fat diets, that would be telling and a reason to invoke ASP, but, as far as I know, no such populations exist.

“So maybe ASP plays a role in obesity in rats that are fed high fat diets, but we’re not all that interested in rats.”

Epilogue – Falling Asleep At A Wedding

My obsessive researching kept me up ‘till 4am, but I had to be up at 8am to workout, shower and be at a friend’s wedding the next day.  I couldn’t put off my workout and sleep in because I had deadlines to meet that night.  So, while everyone else was watching the cake cutting and dancing, I passed out, face down on the table.  Even though I woke with drool on my cheek I felt a lot better.

References

#1.  J Biol Chem vol. 264, Jan 5, 1989, p.426-430

#2. J lipid res vol 30, 1989 p. 1727-1733