Finding Optimal Performance Weight with Body Fat Percent by Matt Fitzgerald

If the method on the Livestrong website is correct, my BF % this morning is 8.4%

How to Measure Body Fat Without Calipers (

FWIW , I am just under 47 years now 5ft 9 in and for symmetry, lol, just out of bed I was 9st 5lbs.
When I left school at circa 17 I was 11st 7lb (circa BF% of 15.6%).

Metrics don’t tell half the story though.
At college I took a bout of pancreatitis and fell to 9st within a few months, that was way too light. (I’m not sure of my waist size then to calculate bf%).
I then lived in Ireland in my late 30’s and with Guinness my weight rose to 10st 7lb (I’m not sure of my waist size then either).
I re started cycling for commuting in Ireland and it became more serious in my early 30s when I moved back to Scotland. That and my reduced Guinness intake, lol, saw my weight fall to 9st 7lbs.
It was stable for years after then until I cut back on my mileage and focussed more on interval training after which it creeped up very gradually during my late 30s to 10st.
On hindsight, somewhere between 9.5st and 10st felt right for me,
Then wham, overnight I suddenly felt like a geriatric. It turns out I had a catastrophic iron deficiency. To combat that I stupidly turned to meat and only then did the frequent sore stomachs which was a sign of a cancer manifesting.
I was then rushed into hospital and came out about 9st after having a tumour removed.
I instantly felt better and more sustainable than I’d ever been but a few weeks later I got hit with the news whilst they were sure they’d got everything, I was getting blasted with chemotherapy. After talking to the docs and to avoid the vicious circle (symptoms>rest>more symptoms> more rest> yet more symptoms> yet more rest, etc, etc), Whilst I dropped my pre op blood infusion boosted FTP by an arbitrary 50w I continued to train (for some reason I decided to keep my eye on max HR though and keeping it below 90%). It worked anyway I’d only really get the severe effects of chemo (upset stomachs and tiredness) for a day or two after intravenous chemo. It did wreck my fingers and feet nerves which are slowly growing back (I’m 3 years out of chemo in November and they still feel weird). If I was miraculously able to reinsert the section of colon lost (circa 6.6lbs) I think I would be in what for me feels like a good weight zone. I don’t weigh much more than when I had pancreatitis as a teenager, which felt way too light, but now it feels about right given my current post op weight distribution (more in my legs than my stomach).

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As my watt gains gets slower I need to look elsewhere to optimise - so only recently i am starting to look at weight…

I am 175cm at 65kg (21.5 BMI) 27 years old.

I have never taken a body fat % test but I am guessing around 15 to 20% - I am quite happy with my body, and for now I will continue my diet as-is but closer to race season next year I will look to stop drinking alchohol and eating junk which is frequent in my current lifestyle!

As a runner 5 years ago i got down to 57kg and still felt very good… so i’d think 60-62kg is definately a healthy weight for my body type - but I am in no rush to make quick weight loss… I generally peak around 4.5 or 4.6 w/kg… so if I can healthily get to around 60kg i might see the big ‘5’ within reach!

Wish me luck…


When we look at pro riders and even high achieving amateurs I think we get sucked into their moment in time. Crit and sprinters are different but roadies are generally twigs with legs and unsustainable body fat levels. That’s not for the rest of us who live in the real world and at 54 where preservation of all muscle mass should be an overarching goal, not at all desirable.

Ride on


It’s always interesting to read how these threads evolve. This one is heading in a way different direction than I imagined. I enjoy reading everyones responses whether their personnel journey or general input.

Overall, I have gained weight over the last few years due in part to reduced lipid utilization (older), part just less active throughout the day and part eating and drinking too much and/or wrong things (booze) and/or timing.

There are so many things I can do to lose a few so I will. An extra 10-15 pounds of fat does no damn good. Whether or not the Matt Fitzgerald table above is germane to me IDK. Whether the Tinata scale gives valid reading IDK. What I do know is if I change a few habits and use the scale in a consistent manner I think a couple kilos from where I am will not only be easy but, way healthier than my current situation.

Lastly, my n=1 observations of group riders and even older racers compared to runners we are very way fatter and would benefit from slimming down.


I don’t have that scale, but pre-dexa I wasn’t using “Athlete” setting. However, on regular I was showing a significantly higher percentage, where as Athlete setting pretty much matched it. I’d just assumed I wasn’t an Athlete in those terms.

I still never got near 10% even at my lightest (which was with a lot of “you don’t look healthy” comments). 12.3% was the lowest at 69.3kg (183cm).


I have a Withings scale so you can take the accuracy with a grain of salt. A little over 6’ and at 175lbs right now I’m around 13%. I can get to 11% pretty easily, but never been able to keep it at 10%. Not because I couldn’t, but I’m just not that dedicated that I won’t go out to eat or have a few drinks on the weekends. And I like cookies.

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I googled around and found this calculator which is much easier to use, especially for us using SI units

It puts me around 12.1-13.7% (depending how tightly I measure)


That site puts me at 9.3%.


I am 62 but started the year pretty near to your stats; 173-175lbs, 15% body fat as measured by my scales (inaccurate but looking at trends). I got some dietician help about 4 months ago in an attempt to lose some weight (I had come down to 171’ish when I started) while working to maintain performance. I am now at 159-161lbs, 11.2% body fat. I had some w/kg downgrade for about 4-5 weeks but have rebounded back to pre-dietician level of 3 w/kg. It’s doable and has been worth the 3-4 months of commitment.


33, currently at 20-21% according to withings. Had a dexa scan which said I am at 25%. My goal is 15% (on withings).

I am 6’3 and 202 lbs right now. When I was 24 I went from 235 to 198 through weight lifting/HIT + diet, and it is amazing how different my body comp is being 202 primarily from cycling. I have recently decided to start lifting weights more to help with that.


One thing to consider…I have the immune system of a rhino…I have taught for 25 years, have had 4 days off in that time. Didn’t get Covid even surrounded by 1000+ teenagers who don’t know how to wear a mask. However, 3 of those 4 days absent came in 2018 when I started TR. I did the old HVSSB…2 hour sessions after work…when I started HV build I lasted 2 weeks - my weight had dropped from 62kg to 57kg and I got the flu…3 days off work, nearly fainted at a parents evening…3 weeks off the bike. Since I have done a hybrid MV with some running. Weight now 61/62kg and back to never being ill…sometimes being super skinny is not good - especially if you work in a school :grimacing:

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Just for comparison, and my N=1. Currently 68 years old, 5’9", used to be 5’ 10" . Currently weight 154,155. Got up to 165 this past winter but this was all around my middle. 15 years ago when I was actively racing, I weighed about the same, mid 150’s. I think as we age, the mirror is a better guage than the scale.


Lots of interesting perspectives in this thread. As a followup I know pretty much when I’m too heavy - without a scale - I feel sluggish on the bike. I also know when I’m too light - my stamina and power fall off pretty fast. My decent weight fluctuates between 175 and low 180s. Recognizing that I carry on general weight training

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Oreo here’s a better explanation how Fitzgerald comes up with optimal performance weight. My numbers as example:

  1. Calculate lean body mass=current lean body weight x lean body mass %.
  2. Calculate optimal body weight=lean body mass/optimal lean body mass %.

So the 10% is arbitrary as I picked it just to come up with a goal weight. The huge unknown is the lean body mass% (from a scale) could be way off. But, without a more realistic way to come up with that number this will have to do. Do I think 164.30# for me is 10%? Hell no. If that were true have been at 10% or under forever and if you saw me you’d realize that the lack of vascularity=not true.

When I calculate for 20% body fat I come up with an optimal weight of about 155 for 10%. I think this is close. But, I have no way to prove/disprove nor do I really care to. With my history of riding weight from 147 to 175 I do know I’m extremely vascular at 155-ish. I also know 155 is probably not realistically sustainable for me. I keep coming back to 160 as a sweet spot.

It will be interesting to see changes in BF as I lose weight even though the scale is probably reading 4-5% low.

@cartsman TBH I don’t know if athlete setting or regular? Not home at the moment but will check soon. I got the scale and just programmed following the prompts and hopped on.


I’m 53 and have dropped 10kg and counting using the app MacroFactor by Stronger by Science. It costs money but worth it.
I also have Tanita scales. The SBS guys have advised that there aren’t any scales that accurately measure body fat percentages. I’ve noticed that weighing myself daily how much the body fat number jumps around. The body weight measure is accurate and consistent.
Check out the app and you’ll achieve your goals guaranteed.


Are you fat shamming cyclists? Sinner.



This thread makes me feel fat. My legs are pretty damn lean, but have always carried some belly fat, currently 180 lbs at 5’ 9". I need to cut some weight, I have been down to 155ish, but couldn’t finish any workout with intensity, 170 would be a good weight for me. In reality, gaining 20 watts will make me faster than losing 10 pounds.

In the past, running was the only way I could actually shed weight, with a rebuilt knee running is a lot harder on the body.

I struggle finding bibs that fit over my legs, how do those sprinters get bibs that fit their quads well?

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Only masters. Me included…:wink:

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My initial strategy was to lose weight until I look thin in lycra :rofl:

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6’3", average weight for August is 167.7 lbs, with my scale reporting anywhere from 8.8 to 9.4% body fat

Currently lighter than usual, and lighter than I like to be - but I’m recovering from injury so was off the bike entirely and have been easing back into very low intensity so presumably my weight will creep up as my blood volume comes back (assuming I’m able to resume training)

I’ve more or less moved away from looking at BF% - this post was the first time I’d looked at anything other than the weight value from my scale in months.

Skimmed the thread - but curious why you’re looking at a target BF instead of a target weight. Wouldn’t a clean diet and focusing on the workouts (weights, bike, whatever) allow your body to dictate whatever BF it needs to support the weight you want rather than trying to control the fat percentage