cmd111183 wrote:
RowToTri wrote:
ZenTriBrett wrote:
RowToTri wrote:
And 130kcal/hr is not absurdly low for a lightweight female triathlete. Her previous number is unbelievably high - 450/hr after the swim - probably higher on the bike. This is more than a large professional male triathlete can handle without gastric distress. No wonder she had severe gastro issues! Just eliminating all the gastro issues from excessive over-fueling during the race could account for her performance increase,
That's not exactly what is going on. As an athlete piles on more and more carbs in their daily diet, they become less and less sensitive to insulin. And then they need more carbs for insulin to extract the same amount of energy out of the food. It's the same process as a kid becoming diabetic from drinking cokes all day. The body becomes numb to insulin, because there's so much insulin being created in response to all the sugar coming in. Stevens wasn't choosing to eat 450 sugar cals per hour, she was having to eat 450 sugar cals per hour to generate the same energy to move forward at the same speed as her competition.
Since that is way too much fuel to digest hour after hour, high-carb dependent athletes like Stevens (and many of us) blow up a while into the run. We either get sick from trying to eat all the sugar we need, or we bonk from our stomachs shutting down right before getting sick and now we can't make the energy to keep going.
The trick that is proposed here is to eat way less sugar and simple carbs in your daily diet, get those calories from fat and slow carbs instead, which in turn increases your body's sensitivity to insulin, which in turn makes your body able to keep running on less carbs coming in.
There's also the problem that carbs coming in signals your body to turn off fat burning, because you don't need fat because you have carbs. So again, less sugar coming down the pipe turns the fat burning furnace on more and more.
In Steven's case, she swapped out the carbs in her daily diet for fat, which raised her insulin sensitivity, which in turn lowered her need for carbs and upped her internal fat usage for fuel at the same time.
The quoted statement above doesn't pan out exactly how you'd think. If she just cut the carbs during the race before fixing her metabolism, she'd bonk. At her past metabolic state, she had to have those carbs to race at all. It's fixing the underlying metabolic issues by adjusting the daily diet that worked and shifted her carb needs to where they are now.
People can go get tested to see how high of a carb burner they are. The Tri Shop in Dallas did it for me a while back and I came back super high, and also recently came back from blood testing as nearly pre-diabetic. All this while being super fit and low body fat from training for Ironmans. The big giveaway is not being able to have a strong workout without gatorade or other sugary stuff. I didn't understand the impact of the high sugar burn rate at the time, because I was way more focused on FTP. But FTP is useless if you've bonked because you can't feed the engine fast enough.
A mistake people make trying to fix themselves is removing too many carbs too soon and/or not replacing their calories with fat. Go slow and enjoy the process.
BTW, "1000 calories from soda is not the same as 1000 calories from broccoli" is definitely true, but if it took as long to digest those soda calories as it took to digest the broccoli ones, they'd be a hell of a lot more alike. :)
Regarding insulin sensitivity, it appears the opposite to what you say is true. High carb, low fat diets actually increase insulin sensitivity.
http://www.rice.edu/~jenky/sports/Insulin.athlete.html
and
http://www.ajconline.org/article/0002-9149(92)90981-4/abstract?cc=y=
I eat all the carbs I want. And I want a lot. And I burn a lot of fat. In Zone 1 I burn 0.87 g/min of fat and in Zone 2 0.86 g/min. This is comparable to the amount of fat burned by some grand tour cyclists they tested and shared the results with me (anonymously of course). The biggest difference was those cyclists kept it level into zone 3 and I dropped to 0.71. Still not terrible, and improvable with the right training. So obviously my high-carb diet has not ruined my ability to burn fat and made me "carb dependent". Inkinen's results of something like 750kcal/hr (if memory serves) from fat translates to 1.39g/min. I think that is pretty un-precedented. I would love to see an expert physiologist's analysis of his results and methodology.
So what actually does increase one's ability to burn fat then? A bigger aerobic engine? Sorry, it's tough to keep up with a lot of the more scientific discussion here and I'm trying to understand it as someone newer to endurance sports and nutrition.
Yep, the consumption of fat unequivocally (temporarily) increases insulin resistance (as well as noticeably slowing down how quickly carbs are digested). The suggestion to the contrary earlier in this thread belongs in the category of interesting (and ultimately incorrect) speculation rather than an empirical observation. The notion that one would want to eat a high-fat snack while working out/racing kind of blows my mind. (I've eaten plenty of high-fat fuel while alpine climbing and winter camping, but those are far longer duration, lesser intensity activities, i.e. you're trying to fuel multi-day efforts.)
As for what (if anything) increases one's ability to burn fat, I don't have any particular insight there.