Help: How do you know when you are overdoing carbs?

I find myself in a very puzzling predicament. As part of a routine checkup, I found out my HA1C is 5.6, implying an average blood glucose of 114, so borderline pre-diabetic. I say it’s puzzling because of my profile:

  • Lean and athletic build, visible 6 pack, despite my age. No to brag, but I look better than most people 25y younger.
  • Not gained weight. In fact I have lost weight. Not excess weight around the waist, of course.
  • Fluctuate between 138-143lbs at 5’8”. THIS IS NOT A CALORIES ISSUE.
  • Consume about 2900cal a day. I track and weight my food. On average 260g of carbs daily.
  • Fit, 4.0-4.2 w/kg at 8500ft
  • Carbs as a % of calories are not greater than 37% on average.
  • Only do more than 60g/h in races
  • No carbs in less than 2h endurance rides.
  • The most I do for a 2-3h hard ride is 30g/h. And it’s mostly fruits.
  • The day I do a 5h /250-300TSS I do 60g/h and consume 500g of carbs total in that day.
  • I lift weights and do other physical activity aside from cycling.

Even if by absolute measures It seems that I’m not overdoing it, maybe relative to my physiology and training, I am. Signs that I could be over doing it, aside from blood tests:

  • I never bunk, rarely too tired (due to diet) to train.
  • Sometimes after a big ride I GAIN weight…albeit temporarily.
  • Despite looking great, DEXA says 19% BF. Could I be under muscled despite appearance suggesting otherwise?
  • Volume has been low (7-8h bike) for last 3 months (indoor season). With 3D of intensity.

It’s important to note that over the last week, since I found out the result, I reduced carb intake, an adjusting the timing a bit, except the day of the big ride and seem to be doing fine energy wise, however not blood sugar wise yet.

Additionally, there’s a tiny chance that this is caused by the small dose of statin (Rosuvastatin 2.5mg), but is highly unlikely.

I’m arranging appointments with an endocrinology team and will get to the bottom of this, but will like to hear input from the forum.

Thanks a lot


I’d have them retest in a week. Had this scenario once and all subsequent tests were not a red flag. (Minus the having a six pack bit)


The thing is that I’ve been testing my blood sugar, fasting and 2h Postprandial, and it’s indeed high and consistent with the HA1C reading.

Did you get numbers on subcutaneous vs visceral fat? Despite being more visible and hiding abs, the subcutaneous fat is the one you want to have.

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64000g body mass. X 19.3% = 12352g of fat, of which 279g is the estimated VAT.

Not to get too deep into your medical history but why are YOU on statins? It just feels like drug pushing at this point, the statin thing is out of hand.

The one thing in this equation that makes no sense is the statins. If there is some concern around your cholesterol then maybe there is something to look at there, for example very high triglycerides, etc. Have you tried ‘eating to the meter’ where you monitor your blood sugar after meals? Then adjust away any large spikes? It could be dose and timing of your carbs. who knows. My mom ate to the meter for a while and saw that morning meals and evening meals had very different profiles which she thought was quite interesting. Makes some sense, breaking fast and all that. She changed up her diet to reduce spikes and after those changes, her cholesterol dropped and her HA1C moved out of prediabetic range.

But honestly of all that it really sounds like the statins should go step one. Sadly, statins are the perfect money maker, they are dangerous to quit. Thanks, big pharma.

No, but they bounce from 40 to 80, never ever higher than that.

Horrible history of hyperlipidemia in family and high ApoB despite being in the top 0.1% of fitness and a clean diet.

It’s also 2.5mg….which is a sub clinical dosis. I also take Ezetimibe 10mg.

Yes that’s why I’m worried.

How’s your Hb, if Hb is low HbA1c tends to be higher

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This is not super relevant since I measure my blood sugar directly.

Post prandial and early morning glucose spikes (dawn phenomenon) are normal. What matters is the damage being done chronically of which Hb1ac can be a measure but not under all circumstances. Otherwise I would get a continuous blood glucose sensor and see how you respond to foods under different situation

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I’m not a doctor, nor am I your doctor, but there is plenty of data out there that tells us taking statins has MANY negative effects, including high blood sugar and insulin resistance. I’ll also add, low carb will also increase insulin resistance, so that is not a very good solution either. If I were in your shoes, I’d try to get off of the statins and continue your healthy diet and training.


It’s definitely not a carb problem. Actually, if interested, a heavier carb diet would very likely cause you to perform better both in exercise and in daily life due to an increase of energy.

Studies that show low carb contribute to insulin resistance? This isn’t what I’ve read, so interested in seeing what I’ve missed.

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few things…

retesting A1c a week apart is useless. A month, yes, a week, no.
Look into Adult onset T1DM. Doesnt sound like your diet or fitness level is the culprit here. Its not really understood why it happens, but it certainly does. One day of eating big carbs while doing a 300TSS ride isnt likely to cause diabetes. Id venture to say your glucose is probably on the low side after a ride like that. MAybe a CGM is in the cards for the next few weeks to track it around the clock?


Long term low carb or keto can contribute to insulin resistance. Yes, it can lower hba1c and blood glucose, because you aren’t taking in any carbohydrate, but it actually can further increase insulin resistance and reduce carbohydrate intolerance. It’s like taking statins for cholesterol, yes it lowers them, but only by limiting your bodies ability to synthesize it, not addressing the reason why it’s doing that in the first place.

My non-doctor thoughts.

  • You seem to not eat enough carbs when on the bike. 30g/h for a 2-3h hard ride seems too low.
  • What type of carbs are you eating? 260g of gummy bears with Coke is very different than 260g of oatmeal with protein powder and peanut butter.
  • Try a glucose monitor for 2 weeks to know your true blood glucose and how it varies by what you eat and what you do.
  • Get a coronary calcium scan to better assess your need for a statin. They’re surprisingly inexpensive. I think I paid $100 at a UCSF facility. The price was without insurance.
  • How old are you? Higher age and unlucky genetics can sometimes cause higher A1C despite good eating and high physical activity. That’s when you’ll probably be prescribed 500mg of metformin.
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I’m similar profile - lean, fit, eat reasonably well - but have HbA1C of 5.5 and high cholesterol. Been that way for the past 10 years when I started getting regular physicals. Unlucky genetics I think.


I’m gonna go with “it ain’t your diet” I know, not super helpful.

Can’t wait to see how it turns out though!


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Yeah similar here. My most recent fasting glucose test showed 5.2 and my cholesterol levels are high. My doctor isn’t particularly concerned and my wife (also a doctor, but not mine) is not concerned at all.

0% 3 years ago

Oatmeal, rice, fruits, veggies. On the bike Figs, banana. Racing and long rides Skratch Superfuel and Maurteen Solid.

Yes very likely. I’m getting tired of pricking my fingers.

I looked at these data and it’s highly unlikely that my tiny even sub clinical dosis is the culprit.

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