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  • Writer's pictureNatalia Roman Lopez

A nerdy experiment fueled by fat & speculation

Before low-carb/Bernstein/keto (20-30g carbs a day, high protein, moderate fat) there was a full year of training and racing on a high-carb nutrition with type 1 diabetes. Back then my endocrinologist (endo) advised to cut basal by half on +4h days. At least 2 days a week are +6h for me, with races between 4 and 24h. I blindly followed the prescribed insulin regimen with somewhat acceptable results. Somewhat acceptable thanks to the fat-burning switch that my body had already been using for years. I would have hypos within 15' but these would stop after 1.5-2h. However each food intake would be followed by a spike and then a drop.

Then, 10 months ago, I discovered low-carb (LC). A new self-learning process kicked off. In parallel the science behind LC, exercise and T1DM absorbed most of my free time. Summer has been a concatenation of long days - keto helps recovery btw! The good news is that somehow my body can stand the exercise load while maintaining normal BG (most of the times). But I want to understand HOW this homeostasis is achieved. What are our friends and foes in this equilibrium? what if we change some of the variables: more/less insulin, more/less carbs, HR, fasted...but at the same time, why changing what works?!

Anyway, let's get to the point. On LC I inject 12u Lantus 6/6 evening-morning. With reductions up to 2u. Sounds crazy to reduce basal by less than 20% when going for a 10h mountain run. During such days I very rarely have a hypo. If so, I can correct it with 2-4g of dextrose. Another interesting fact: I can get going with insulin on board from recent boluses. How come BG flattens at 3.4 no-matter-what?

From all the reading there is one hormone that fascinates me: GLUCAGON - thought to be dysregulated in type1, hugely under-studied and not routinely (even less continuously) measured. My hypothesis: what if glucagon shows up to save the day? of course in the context of fat burning from the onset. I'd assume glucagon is overwhelmed/over-riden/numb on HC (and high insulin!). could it be that I have been 'unnecessarily' injecting basal?

This was my test protocol:

- Evening basal 6u

- Skip morning basal dose.

- Cover a high protein breakfast w/ R. I actually added 1u ultra fast 30' before exercise.

- Backcountry ski from 10am to 2pm. At least 3h uphill and mid/upper-mid effort.

- Ultra-fast boluses in case the lack of basal raises BG

- No food except for dextrose to treat hypos

- Inject 2/3 of daily basal after skiing and go till the next morning

Part 1: what happened during exercise

The curve while exercising looks no different to a full-basal day. Perhaps the initial gradual drop was faster due to the 1u ultra-fast only 30' before starting the vigorous uphill. The most interesting insight is that at 3.4 BG simply FLATTENS. I did not treat it (pls ADA don't call the sugar police). Why? first, because I was feeling great. Second, because I wanted to see which direction BG would take. It flattened but i still kept pushing the uphill for 2 more hours!!!

What do we learn from that:

- Lack of morning basal was irrelevant - no highs.

- In my opinion, glucagon kicks in whenever needed.

Part 2: what happened post-exercise

The 9u basal injected at 2pm did the job wonderfully till 8:30am when I went back to my 6-6 regimen. Before someone raises the DKA flag... check those ketones!

BREAKTHROUGH: glucagon could have been counterbalancing a basal 'overdose' for months!!

Further testing coming up the next two weeks. It does feel like landing on the moon nevertheless! I wonder if that extra insulin could have additional anabolic effects that explain my non-stop muscle gain... to be continued... Stay tuned!!

Side note for my non-type1 sporty friends: burning fat for fuel is an endless and steady source of energy. If you are an endurance athlete the improvements in performance are most pronounced during the second half of the workout/race. You stay steady while your carb-burning friends/competitors run out of fuel or suffer the swings of BG & insulin coming along with the gels - not to mention the stomach issues.

I am happy to answer your questions, pls just drop a message in the contact form below :-)

Also thrilled to hear your experiences. We are on the learning boat together!!

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Jose Gabriel
Jose Gabriel
Feb 20, 2023

Hello Natalia, Just found your blog while trying to see if there's someone doing keto/LCHP and Marathon Training / traveling long distances. I would love to hear more from your story. I also read Bernstein and it's life-changing, honestly. Keep it up with your blog, the imagery looks awesome!


Feb 18, 2021

Do you use a CGM?

Natalia Roman Lopez
Natalia Roman Lopez
Feb 25, 2021
Replying to

Yes, the glucose graphs you see are from my Dexcom G6.

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