Appreciate you digging into this study, Brady. The detail that matters most: beta-CTX rose while P1NP stayed flat, so even with calories matched at nearly 3,900 per day, four days of low carbohydrate availability uncoupled resorption from formation.
One nuance for readers: beta-CTX is strongly suppressed by feeding, especially glucose-driven insulin, so part of that rise may reflect the loss of normal post-meal suppression rather than true net bone loss. Four days is far too short to know whether remodeling balance actually shifted.
Still, the practical takeaway lands. "I eat enough calories" is not a clean bill of health for bone. For masters endurance athletes already at higher fracture risk, stacking a low-carb strategy on high training volume looks like a plausible way to nudge resorption upward without noticing. Timing carbohydrate around training, as you noted, seems like the safer experiment.
The author has missed the bigger application here and that is to people who need under fuel to get to a healthy weight, that process might take months or possibly years. That person needs to exercise in a near constant calorie deficit to do so, surely that isn’t going to be causing bone problems?
That is I believe why strength training is an important part of a fitness and health regime
I think it’s a pity that that study was only done in men. I wonder if women showed a different response or rather a more sensitive response to low carbohydrate availability.
I'd also be interested in an extrapolation to see if carbohydrate and energy TIMING have an impact on bone - i.e. training fasted or not fueling adequately during exercise, thereby creating within-day energy deficits even if total intake is sufficient
Appreciate you digging into this study, Brady. The detail that matters most: beta-CTX rose while P1NP stayed flat, so even with calories matched at nearly 3,900 per day, four days of low carbohydrate availability uncoupled resorption from formation.
One nuance for readers: beta-CTX is strongly suppressed by feeding, especially glucose-driven insulin, so part of that rise may reflect the loss of normal post-meal suppression rather than true net bone loss. Four days is far too short to know whether remodeling balance actually shifted.
Still, the practical takeaway lands. "I eat enough calories" is not a clean bill of health for bone. For masters endurance athletes already at higher fracture risk, stacking a low-carb strategy on high training volume looks like a plausible way to nudge resorption upward without noticing. Timing carbohydrate around training, as you noted, seems like the safer experiment.
- Moses
The author has missed the bigger application here and that is to people who need under fuel to get to a healthy weight, that process might take months or possibly years. That person needs to exercise in a near constant calorie deficit to do so, surely that isn’t going to be causing bone problems?
That is I believe why strength training is an important part of a fitness and health regime
I think that omission was purposeful, David! This article was more geared toward the athlete/ person prone to underfueling! Thanks for reading.
I think it’s a pity that that study was only done in men. I wonder if women showed a different response or rather a more sensitive response to low carbohydrate availability.
I’d speculate, yes! Hopefully they have a plan to do this in a female cohort.
I'd also be interested in an extrapolation to see if carbohydrate and energy TIMING have an impact on bone - i.e. training fasted or not fueling adequately during exercise, thereby creating within-day energy deficits even if total intake is sufficient
The answer to that is absolutely yes.