70lbs gone and counting!!
Fat 2 Fit - One Woman's Journey
For example, if you fast for more than 24 hours and you are relatively lean, you will see on the order of a fivefold increase in secreted growth hormone. This has a twofold effect :
- It promotes lipolysis ... mobilizes fat stores to make them available as an energy substrate.
- Related to the first point, this is protein sparing, as tissues that can use fat now rely on the increased FFA availability for energy, lowering overall glucose needs, and attendant gluconeogenesis from protein substrates.
But let's assume that we consider fasting and potato fasting equivalent, so we eat nothing but potatoes for a couple of weeks, as you mentioned. We will bathe our metabolism in glucose periodically, resulting in elevated insulin levels throughout the day. An interesting question to ask is what would be the effect be on growth hormone? Well, according to Ji. et all:
A subsequent investigation led them to conclude that :... we found that insulin pretreatment for 8–24 h downregulates GHR levels and inhibits the acute effect of GH on STAT5B phosphorylation via the GHR/JAK2/STAT5B pathway ( Ji et al. 1999).
So, these studies tell us that after a mere 8 hours of elevated insulin, the number of growth hormone receptors starts to get down regulated. Well, so what? Not much, except that this is the exact opposite result of what happens when you fast. Overall, then, when you potato fast, you are less responsive to growth hormone effects. The one effect that is most bothersome here is the absence of the protein sparing benefits of growth hormone that result from mobilizing fat.The present studies indicate that prolonged hyperinsulinemia, such as that found in some obese patients or patients with Type 2 diabetes mellitus, may have profound effects on GH signaling via STAT3 and STAT1.
On the all potato diet you insist on forcing your metabolism to subsist on glucose, and if you eat conventionally, where that means multiple meals, you effectively maintain high insulin levels throughout the day, suppressing fat mobilization. Potato proponents have also advised that you do not count calories, so you may be eating well below maintenance requirements, or maybe you aren't, but you don't know because you are oblivious to your caloric intake.
So what happens if you don't get enough glucose? Well, you're going to have to find it somewhere, because you are forcing your metabolism into an "all glucose, all the time" mode. Your energy options are therefore severely limited at this point to glycogenolysis or gluconeogenesis, and if you keep at it long enough, you are explicitly forcing your body into gluconeogenesis. And a very nice substrate for gluconeogenesis in the presence of suppressed fat metabolism is protein.
But isn't this the case with fasting as well? No, it isn't, because if you keep at it for prolonged periods, as a direct consequence of increased fat metabolism, your body becomes ketone adapted, which grossly reduces your glucose needs to about 1/3 of what they normally are. Of the substrates that the liver can use for gluconeogenesis, a very nice one is glycerol, which happens to be the backbone of triglyceride molecules, which the fasting metabolism is furiously stripping down to provide FFAs for energy for the tissues that can oxidize fats, whereas the liver is furiously churning out glycerol based glucose for those tissues that absolutely must have it.
Whenever I mention to people that I habitually fast for 48 hours, I can hardly get the words out of my mouth before someone starts pestering me about the "starvation response" and muscle wasting nonsense. If I were to go off the deep end and suggest fasting for a couple of weeks, they would seriously question my sanity, of that I have no doubt. But, when you look at that monster potato hack thread, you will see people blithely advocate just potatoes, with indiscriminate calories, for weeks on end because they are "a complete protein." As if that actually makes a difference when you are consuming starvation levels of it.
But have I not been exploring the "magic" of potatoes as a side project? Yes, I have, but I have modified things to correspond to my understanding of metabolism. Specifically, I eat only one meal a day, which limits me to one episode of elevated insulin levels, rather than chronic levels throughout the day. Second, I make sure to eat sufficient protein, well in excess of what would be possible with potatoes only. Third, I measure my caloric intake fastidiously, as well as my weight, my caloric expenditure, and my body composition via both bioelectrical impedance and ultrasound measurement. I am not interested in weight loss at any cost. I am, however, avidly interested in body recomposition and how to best achieve that.
I only briefly scanned your blog, and saw no weight loss but I didnt look closer to see if any redistribution or recomposition? I would think that a person of low fat would not see the same kind of weight loss as a person with more to lose, but if it is doing anything for you, it might not be weight loss but you are more likely to see some definition?
70lbs gone and counting!!
Fat 2 Fit - One Woman's Journey
Last edited by Paysan; 11-12-2012 at 04:29 PM.
"Times fun when you are having Flies" Kermit the frog
PK, about what would you say is the difference in insulin levels between your average insulin sensitive potato faster and a hyperinsulinemic type II diabetic (eating normally, I suppose)? Also, are you aware of any high carb calorie restriction studies that measure loss of lean mass?
I kind of have a hard time believing this little potato hack would have essentially the same effect on GH, lipolysis and muscle wasting that you would see in a diabetic.
By the way, can you provide a link to that study you quoted?
That was interesting to read how it works. So I guess you can starve to death eating only carbohydrates or only lean meat. I don't remember if you can starve to death eating only fat. You can live indefinitely on just lean and fat meat. Meat eaters are we.
Female, 5'3", 48, Starting weight: 163lbs. Current weight: 135.
Starting bench press: 30lbs. Current bench press: 75lbs.