Weight loss and performance | 80/20 Endurance

Weight loss and performance

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    Hi David

    Over the past 6-8 weeks have been in maintenance mode since events being postponed. So I steam been focusing on getting down to racing weight.

    Just stepped training back up again, but the harder sessions I’m struggling with top end efforts.. anything that is top of zone 3 and beyond.

    For example – ran 21.4 kms today but just could not go faster than 5m/km when my threshold is 4:30.

    Is this likely due to dropping weight? (managed 3.5 Kgs in last 4 weeks) and generally gone from 93kg to 80kg over past 15 weeks.

    My form is ok -5 to -10 but legs have been feeling a little dead recently (DOMS like).

    thanks for any insight.

    Thanks CML

    David Warden


    Thanks for checking in. Losing weight can be a help or a hindrance in performance. Ultimately, weight does not matter (if it did, then a 3,000 pound Ferrari would be slow). What matters is power-to-weight ratio. If that improves, regardless of total weight, you’ll be faster.

    So, is your weight loss due to losing fat or muscle? The former would improve power-to-weight ratio, the latter might actually make it worse.

    This is a long way of me saying: I don’t know if your weight loss is related to your current struggles with high intensity. It might, and it might be in combination with just coming back into formal training.

    For now, don’t worry about higher than Zone 3, even for Zone 4 and 5 intervals. Lower Zone 3 is still high intensity. It’s not 80/10/5/5 training, it’s 80/20: 20% at high intensity. Yes, distributing and polarizing that high intensity over Zone 3, 4, and 5 is best, but you’re still going to get most of the benefits of high intensity if you just hold low Zone 3 for now.

    Your fitness will come back and you’ll be rocking those Zone 4 and 5 intervals within a few weeks if you stick with a plan. This is a normal part of cyclic and periodized training.



    Hey David

    Many thanks for the rapid response 🙂 it’s made me think a bit more about it logically.

    The weight loss has mostly been fat rather than muscle.. but I will go get another DEXA scan to double check. When doing your level 2 Ironman I have a reference point, so can compare.

    The loss of upper zone 3 – 5 has only been past week or 2.. during maintaining I was hitting climbs and setting PRs. So was losing weight and therefore increasing power to weight. I could compare climb segments and see I was climbing faster for the same power.

    The past 3 weeks have average 750 TSS and this week 840 – whilst maintaining was keeping about 600.

    So like you said might just be a reaction to increasing volume/intensity.

    Will up the food intake to match the training and ease back into Zone 4-5 training sessions.

    Love the training plans and always follow them as closely as I can.

    Thanks CML


    Your description in the original post sounds like lack of carbohydrates/glycogen. Your answer to David’s post confirms the same. How do I know?
    I have insulin resistance and need to check my carb intake if I want to lose some fat until the next event. My carb intake during marathon training is limited to 100-130g/day, except for the last 4 days before the thing. That makes it almost impossible to hit the higher intensity targets you described. So, before a day where I need to do high intensity stuff, I up my carbs just a little, which works fine for me.
    I know my required carb intake for a long run so I don’t get the dead-leg syndrome you described. It takes quite some testing and manipulating. But, hey, when I started, I was 265 lbs, and right now I am at 150. So yes, it can definitely be done.


    Thanks for that and my mate reminded me I had done this before during Ironman training!!

    I usually track all my food via MyFitnessPal when in training, but stopped during maintenance as wanted a break from it and didn’t think the intensity was high enough to worry about it.
    Obviously trying to ramp back up intensity/volume I should have started to ramp up carb intake as well.

    Ah well, another lesson learned 🙂

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