That is certainly part of it at the macro level, but there is another level of fitness I personally can’t get through training along. I need to drop that last 5 lbs to get there regardless of what I’m doing on the bike. Like I said, it may be more about diet than actual BF% because those always “peak” together. It could also totally be in my head, but whatever works…
Calipers would be weird for me, I slammed hard on my right side 3 years ago and there is still a bunch of junky scar tissue under there that hasnt gone anywhere. The other side is much smaller.
There’s obviously going to be significant cross-talk between training volume and leanness, but thermodynamics would suggest that the less of your ejection fraction that goes to keeping your core temperature below 40 degrees Celsius the bigger your VO2 (in absolute terms).
Of course, I may be completely off base, since I’m not an expert in physics or physiology…
Yes, you are right, I stand corrected.
I would put some asterisks here: if you are peaking and all the stars align (power, freshness, race weight), then yes. However, I think more long-term, a slightly higher weight is advantageous.
AFAIK not being at the lower end of what is feasible for you all the time will reduce the probability that you get sick. That factor alone will be much more important for most athletes. In my case, this has definitely proven to be true, although N = 1 does not a statistic make.
Obviously, if your body comp is far from ideal, then also yes, you will be fitter if you have less body fat on board and the above does not apply.
No. No no no no.
DXA is thought to be a gold standard for body composition. This is not based in fact and I’m not sure where it originated from (note: cadaver study is the gold standard for body composition, but as an attending once said to me, “autopsy is a never the best time to make a diagnosis”). DXA may end up being the practical standard for assessing body composition, but I don’t think the sport science community is ready to make that declaration. DXA has many, many sources of error that get amplified with repeat measurement (meaning it’s hard to track your progress).
Refs (both open access)
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That’s what I heard, too. I think this was covered on Sigma Nutrition (?) a few years back. Apparently even software upgrades on the same DXA scanner can lead to quite different numbers. Ditto when you upgrade your DXA scanner with a new one. That obviously leads to problems when you do scientific studies and expect DXA to be the gold standard.
Agree with all of that. I probably should have stated - I’m a 50+ guy that isn’t sniffing sub 10% BF. I’ll push to the upper teens in the off season (maybe over 20% at times) and I’m doing well to hit 12% when I’m at my leanest. My point was that most amateurs are probably nowhere near the body comp danger zone where you start getting sick or negatively affect performance. I’m sure there are exceptions and it sounds like you’ve been there. Also, maybe there are benefits to carrying a little extra fat beyond a healthy minimum level, but I’ve never seen anything showing that.
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Within your context this makes a lot of sense. 12 % body fat at 50+ is great, by the way, I hope I’ll be able to hit that in 8 years, too. 
I went from 12ish % to 16ish %, which ballooned to 18 % over the holidays. (When the pandemic started, I made a conscious decision to gain a few kg to reduce the probability of illness. Plus, all races in Japan were canceled/I decided not to participate.) Now I am working on shedding the extra body weight. I have already lost 1.4 kg so far. I would like to lose about 2.5 kg more and hover around 73 kg.
I have two small kids, and they are constantly sick and I don’t want to deny them hugs and love when they nose is running (which seems to be about 360 days a year). 
Once they are a bit older, I might be less at risk. At least that is my hope.
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Thanks, I looked through that first article and the issues with DXA discussed mainly have to do with best practices. The implication is that using a DXA isn’t like weighing yourself on a scale, and any old scale will do—I agree with this, and I think it is an important cautionary note. In the US, you can google “DXA near me” and find tons of DXA services, including some operating out of supermarkets or even mobile units in the back of a van. Since a lot of the value in DXA’s is being able to compare changes over time, I would be concerned about the consistency of results from such services.
In my own case, I have had all my DXA’s done on the same machine at an R1 research university, by the same tech every time. I schedule my scans for the morning prior to eating, and try to be similarly hydrated each time. I don’t follow a crazy diet (at present 
)*
TLDR, use a reliable scanning service, use the same machine, be consistent in your preparation for the scan.
Isn’t it already the de facto standard in published research?
*I got my first scan in April 2021, when I started a keto diet. I did a followup scan three months later in July 2021, just a few days after I had completed a 72hr fast. The tech told me at the time that this could have skewed my results, due to glycogen depletion. In any case, by February 2022 I had moved on from all that keto nonsense and had acquired a wattbike, so I got a third scan to have a benchmark for my “pre-bike” body composition. I then did a couple followup scans and they showed the effect that biking was having on my body. I am scheduled to get another scan next week, to mark one year since my pre-bike benchmark scan, and I plan to get a scan every six months or so going forward.
I can tell you that these scans have been a great source of feedback and motivation for me as I have tried to reverse the effects of a couple decades of neglecting my health in my mid-50’s.
At the same time—and to tie this back into the theme of the thread a bit—these results also keep me realistic on further weight loss. At 192cm, I am finding it difficult to get much below 85-86kg. My last scan in October showed body fat of 12.8%, and I suspect this number is now under 12%, maybe down to 11%. It’s hard to imagine I will get much lighter without dieting or losing lean mass, and I consider those things a dealbreaker—as Peter Attia likes to say, no 90yo has ever wished that they had less muscle. Likewise, I don’t think it’s healthy for people in middle age, who are not former bodybuilders and whose job title is not “professional cyclist,” to shed lean mass simply to improve watts/kg. Personally I only care about absolute FTP on a lean frame. Let the little guys win the watts/kg contest, so what?
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I’m a researcher in this field. My point is that while it has been used as a standard in the past, many of us are now questioning whether it should be used as such going forward.
I’m also of the belief that body composition measurements (serial or one-off) in non-elites can be problematic, but that’s a different can of worms.
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I’m not implying you aren’t a very strong ‘big guy climber’ in the Ottawa area (I have no idea who you are), but I’m pretty sure Emile Hamm takes that title (unless you are Emile Hamm lol).
Could you crack open that can open a little bit? Body comp seems like a really good metric to me (even for general population. non-athletes), but I’m far from an expert and would love to hear another viewpoint.
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So I’m right on the big guy borderline (85kg), but I’ve had a goal for a while now to get to 4w/kg. I’ve been using TR for over 4 years now, so the increase in FTP these days is realistically ~3% max per year. I am still committed to increasing my FTP and am currently playing with adding training volume in small amounts where I can to help with this.
If you are like me and have been training for a while, I would highly recommend putting more focus at the other part of the W/Kg equation.
I’m 6’2" and have a relatively muscular build, especially my lower half. After being consistent with TR for a few years I was hovering around 91kg. The thing that changed was last year when I did the Dialed Heath Shred in January. The nutrition portion of it where you are doing the calorie counting with a small calorie deficit (I used MyFitnessPal) was what really made the difference. I did it for a month and lost ~5kg getting down to 83kg. I also did Dry January which also really helped with cutting the calories.
I think I could have gotten a little bit lower if I did it longer, but honestly doing calorie counting long term is a little more work that I’m willing to put up with. That said, doing calorie counting once in a while really does seem to help making better food choices even when you’re not calorie counting - I’ve not really gone much over 85kg since last year.
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Speaking of gold standard body fat percentage estimation…
I have be contemplating whether I couldn’t find a way to do hydrostatic weighing at home, since I have bathtub is that is more than deep enough to submerge my entire body under.
But then I did the math, and being off by 300 grams is equivalent to an error of almost 2% body fat at my height and weight. No wonder hydrostatic weighing is so expensive and error prone.
He is one of the other big rouleurs in the region for sure, but he didn’t post a faster time last year on the segment.
It’s hard to pick apart as many fast group rides are responsible for people setting PRs.
The key detail is your age, I’m guessing (hoping) that you are a bit older than me.
What’s the segment you are referring to out of curiosity?
2016 TT out, the uphill section of the 2016 selection for the Canadian men
Empirical Cycling has an interesting podcast about this, the hosts talk about (cycling) power and the relationship with body size, and the impact muscle has on cycling performance.
I seem to top out @ around 180lbs (@5’10") before I just start putting on excess fat, no matter how much lifting I do! This seems to put me on the higher end of the ‘cyclist’ spectrum. I’m 177lbs/80Kg at the moment and at my highest absolute FTP, and 4.1w/kg.
Last season @ 172lbs and 3.9w/kg, I increased volume from ~7-8hrs (previous 2 years) to 10-11hrs/wk in October '22, along with starting to lift 5x5 again. Target events of criteriums and rolling road races I wanted to hit chads sprinter lifting benchmarks (albeit for 5x5 not just 5 reps 
)
A ~33% increase in volume (as Z2/LT1 work) equated to ~10% FTP bump, that was in base (Oct-Jan) with 1x Vo2/Threshold session a week. My 5s power was also up 200w on previous PB’s with no specific training (no doubt lifting contributed)
I’m probably 15-20% bodyfat, I have been down to 8-10% when I was younger and exclusively lifting, it didn’t feel great and with 10,000KJ of bike work a week + 2 lifting session I don’t want to jeopardise the work for extra w/KG, I’d rather just the raw watts.
I don’t think there is a magic sauce for anyone ‘big’ or ‘small’, the more I train the more I conclude its volume that really matters, the sexy sessions are just icing on the cake.
I’m hoping during build I can squeeze out a few more top end watts and TTE, if I could do 15hrs a week I would (gradually!) as I am convinced this would probably push me closer to the 4.5w/kg mark.
Personally I think most people looking to the type of workout for big gains are barking up the wrong tree, if you want to be faster, then ride more than you are right now - and do it consistently.
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