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How to lose body fat through Ironman training

Jul 02, 2021


My Top Tips for how to Lose weight and still maintain energy levels through ironman training - without affecting performance

  1. Eat strategically
  2. Get a sports Dietitian Approved meal plan
  3. Let training drive the change
  4. Do it earlier rather than later
  5. You shouldn’t be race weight all year
  6. Conversely - you don't want big fluctuations of 5-10+kg
  7. Slow and steady wins the race
  8. Track changes with skin folds -  not the scales

If you are looking for a Sports Dietitian to help you with training and racing nutrition, learn how you can work with me HERE



Good morning everyone! Welcome to Coffee and Question! So I had a couple of weeks break there because my voice failed me, it’s still feeling pretty scratchy. So I'll see how it goes today, see if it holds up for me. But I'm sorry about the delay, a bit late – the internet is not working this morning and a bit of carnage going on in our house as well.

I’m definitely a bit late but hopefully that’s given people enough time to go and grab a coffee and join me this morning for Coffee and Questions. There's a bunch of people jumping on Insta, so Welcome! Thank you for joining me. I've got a really good question come through from one of my Ironman athletes, so I thought I’d talk about that today.

He wants to know how to lose weight while still maintaining his energy levels for Ironman training. He’s doing Port Macq in what 10 weeks now? I think we’re about 10 weeks away from Port Macq because it got postponed to September. I think this is quite a common thing for people doing Ironman training. Everyone wants to lean up. Because, I guess, power to weight. We always talk about power to weight ratio; you want to be as light as possible but also really strong. And I guess for an Ironman, you've got to carry your weight across that distance all day.

So the lighter you are, the better. BUT I guess as a Sports Dietitian who's been in practise for more than 13 years now, I see a really delicate balance with that. So it's really important to be lean, but you also need to make sure you're super strong at that weight. And I find that the stronger you are and the more muscle tissue you have on, the better than just trying to just get skinny. Like the message shouldn't be just get skinny.

I think that was probably the message maybe 10 years ago, particularly in the more elite space. The athletes were just like, super, super skinny, super lean. But weren’t in particularly muscley. And if you take someone like Flora Duffy as an example, if you have a look at her photos from 2014 or earlier to 2018 -2019, what she actually did was put on a whole heap of muscle, and then she started winning. So I think it's really important to understand that you want to be as lean as possible for racing, but there is a delicate balance between that and being too lean and also you want to be really strong at that weight too.

I've got a couple of good tips and good strategies for you around that. I think it's something I see really commonly in private practise. Everyone wants to come and lose a few kilos, but there's a few important considerations for that as well.

So a few tips for you for how to actually, I guess when Burkey asked for losing weight, I assume dropping body fat. So I'm going to talk about that. I'm not talking about just losing overall weight, including muscle. We're going to talk about losing body fat and maintaining those energy levels right through Ironman. I've got a few thoughts and comments for you around that.

Eat strategically

My number 1 tip - for trying to lose fat while still doing Ironman training is to make sure you're eating strategically. So one of the things I bang on about all the time is that you shouldn't eat the same thing every day. Like you should have some scale in what you're doing so your food matches training load. So you want to eat differently on a rest day versus a really heavy training day and then like a double session hard intensity day, you have a different strategy for that too. One of the things that I work with with my clients is they get a detailed meal plan to help them scale that and have a periodised approach across the week.

I often see people come in and their food dairy is eating the exact same things across the week. And the first thing I do is change that. So if you want to maintain energy levels for training, just doing that anyway even if you're at the body composition that you want to be at, then that's something that I'll do with you anyway. But if you're trying to drop body fat and still hold a really high level or high number of hours of training a week, then it needs to be very, very strategic because otherwise you’ll fall into a hole. We don't want to go catabolic. We want to make sure that you are still fuelling training and you're still laying down muscle tissue and recovering from sessions properly because that's what's going to make you a better athlete. Otherwise, you run the risk of being injured and getting sick constantly and just breaking before the start line.

So it's really important that you have a really strategic approach if you're trying to do that, rather than just trying to scale back, scale back, scale back like that's not a good sort of strategy if you're trying to lose weight because you will get injured, sick, broken.

So that's my number 1 one tip is that making sure you have got a strategic plan for what you're trying to do if you're trying to drop body fat while still building to an Ironman and that I change my plans throughout the Ironman build too. So that's why I only do packages for Ironman athletes now, because there is so much that you can F up with your nutrition in an Ironman.

You can kind of get away with things for sprint, maybe Olympic distance as well. 70.3 things start to rear their ugly heads if they exist. But Ironman, you just can't, you can't get away with anything. So I will only work with Ironman athletes over a longer period of time now because there's lots of stuff that I want to do with you heading into an event to make sure that you have the most successful day in the office come race day.

Get a Dietitian Approved Meal Plan

I guess my main tip is eat strategically and then have a dietitian, a sports dietitian, write a meal plan for you so that you have something to follow. And I find triathletes in particular are good with a plan and you follow it because that's how you work. You know, you like to make training peaks go green. So I set my meal plans up like that as well. So you just know exactly what you're eating day in, day out and it changes. It's not the same every day. So that's really important.


Let training drive the body composition change

When I try and get athletes to drop body fat in an Ironman build, I really try and let training drive the body composition change rather than chase it. And I think that's one of the important things to consider when you are dropping body fat is that if you're eating well and you're doing a good job of fuelling training. You will naturally drop body fat if you're eating properly without having to really be aggressive with a calorie deficit and trying to really chase body fat loss.

If you are eating, you know, to plan that's done by a dietitian and you're being strategic. So that what you're eating every day is different to match your training loads, then you will naturally drop body fat anyway. And I find that happens a lot. Like people often come to me eating the same thing every day, or they also come to me eating not enough. Sometimes if I increase food in certain days that really need that extra fuel, then you do a better job of eating to support training, and that helps to let the body relax and also not play hungry catchup for multiple days after if you haven't done a good job of feeling big training. That helps you to drop body fat as well. So it's a whole big melting pot of stuff going on, which is why I think it's really important to have a dietitian, a sports dietitian, write a meal plan for you. Because all of that back-end thinking happens without you even knowing about it. So let training drive that body composition change rather than trying to chase it. But you need to do that with obviously eating properly and having some strategy around that.

Do it earlier rather than later

My other tip for dropping body fat in an Ironman build is to try and do it earlier rather than later. Now you want to be trying to drive some body fat loss and some fat adaptation, like you want to get your body used to burning fat as a fuel. You want to do that early because that helps you through Ironman as well if you can rely more on fat stores than just throwing heaps of carbs at the system, you'll have a better day on the day as well, if that's you.

I suggest doing it earlier rather than later. So, you don't want to be chasing your tail right at the back end of your Ironman build trying to drop weight then when your training level is at its peak and you should really just be focusing on fuelling for performance at that time. So, you want to do your body fat loss a bit earlier in your training build, which is again why I work with Ironman athletes for a 20-week program because we do that stuff early and then at the backend of training when you’ve got all your good race nutrition practice sessions the big long bricks and stuff, we’re not still trying to drive a whole heap of body fat loss then. A little bit might happen naturally just with that overall training volume - Let training drive the change. But you want to do the fat loss a bit earlier so that in the backend when you just need to be stoking in the fire, so to speak. You can just throw way more fuel rather than still trying to restrict what you’re eating. So, lose the body fat early rather than later.

You shouldn’t be race weight all year

My other tip with this that I see quite commonly, and I have this question asked a little bit, is that you shouldn’t actually be race weight all year. You want to have, again like food, a bit of periodised approach and have some eb and flow to your weight across the year. You don’t want to be Ironman lean for 12 months. You want to have some small fluctuations in your body composition so that you can race at your peak physical state and fitness but then it’s okay to gain a couple of kilos after that. I don’t think you should have big fluctuations. I’m not talking about 5-10kg of weight change. I think that’s too much. But a few kilos here and there is totally fine, and I’d encourage you if you’ve just done an Ironman, you’ve just done Cairns IM and you’ve dropped a few kilos, I’d probably put them back on. It will naturally happen potentially depending on how loose you are with your food afterwards. Make sure you are not race weight all year.


Your race weight is something that can evolve overtime as well, it doesn’t have to always be a set number that you’re always aiming to achieve. As athletes who are in the sport for longer, if you eat properly, I see my athletes they build muscle over the years. So, if I do their skin folds, then they actually get leaner, but their weight is a little bit higher than when they first got that lean. I’m always strategic with my nutrition. You never have the same plan that you follow forever, depends totally what you’re doing. Having some eb and flow to the year as well. Make sure that you aren’t race weight all year. It’s okay to lean up a bit for racing and then put a couple of kilos back on but not big 5-10kg fluctuations. That’s not good for our health – cardiovascular risk, diabetes risk etc.

5-10kg is too big a fluctuation. So making sure you don’t come and see me for an Ironman prep and need to lose 10 kilos – that’s not so fun either. I’m working with an athlete now who does that, and he’s done it twice, and this time we’re not going to do that. He’s going to try and maintain his weight closer down to what his Ironman ideal race weight is. You know, couple of kilos up is fine but we’re not going to have a massive 10kg deficit to hit next year for Ironman.

Slow and steady wins the race

My other tip for body fat loss with Ironman build is slow and steady wins the race. I think a lot of people have really high expectations of what their weight loss should be - losing a couple of kilos a weekly type thing. There’s no way you can maintain your energy level for Ironman training if you’re trying to lose that much weight. It would also be impossible to drop only body fat if you’re trying to aim for such an aggressive weight loss. When we’re trying to lose weight, we’re just trying to lose body fat right. We’re not trying to eat away our muscles because we need that for our strength. Particularly on the bike and particularly not so much Ironman but the more draft legal style racing. You want to have much more strength than just the time trial type style racing. When we’re losing weight, we only want to be losing body fat, we don’t want to be losing muscles. The more aggressive you are with trying to drop more weight quickly, the higher the risk of eating away at your muscle.

A good sort of slow steady weight target is maybe 0.5-1.0kg/week – maximum. It might happen a bit more quickly to start with, you might find that if you go from whatever you are eating to a dietitian approved meal plan, then you might find that the first couple of weeks you do lose a kilo but then it slows down. We also let training drive that adaptation and that change too.

Slow and steady weight loss is key for making sure its fat loss that’s happening, not muscle. Also maintaining your energy levels through that build too. I don’t want to see somebody that’s trying to lose 10kg in an Ironman build. That’s not so fun. That’s why I think you should have a tighter range of body composition fluctuations across the year rather than big gains and losses. And I find a lot of Ironman athletes used Ironman to do that. To bring their weight down so they have an ‘all or none’ mentality where they’re ON and they’re doing Ironman training and they’ll lean up heaps and then they’re OFF, then beers happening, coffee and banana breads everyday – the habits don’t get fixed by doing an Ironman. I’m going to talk about that as a topic for another day just to round those habits. An Ironman doesn’t teach you to eat well.

Alison Ryan said on Facebook “Some people put 10kg on in their first feed post- Ironman”

Often with an Ironman, if you are in a real hole, you might have dehydrated yourself by good few kilos so that first feed you could put on a couple of kilos just with rehydrating. And think about also in an Ironman you have just emptied your glycogen fuel tank, you don’t have any carbohydrates stored in your muscle anymore if you’ve gone hard enough so just by eating carbohydrate over the next couple of days, you’ll gain a kilo or two just putting that glycogen back in the fuel tank.

When I write Ironman race plans, I always write their recovery nutrition in there as well to make sure that the recovery boxes are ticked properly first before you go to Maccas or the pub. So I think that’s important to note.

Bec said “It took me a week to even eat properly again after my first Ironman.”

It totally depends on how that first Ironman goes to and how your gut goes but we know that really high intensity exercise blunts your appetite too so a little bit of force feeding can’t go astray in that first window if that’s you. Because your body is really smart, it’s going to catch itself up later, it’s just going to start sending out all your hunger hormones and then you’ll be just like a bottomless pit - open the flood gates and you won’t be able to stop eating once that happens. And that’s the body being really smart and trying to catch you up from the hole that you’ve just put it in.

Maree said “great advice”

Bec said “It took me two years to eat vegemite again”

I see that often you OD on a product and you get flavour fatigue and then you can’t face it again. It often happens with things like sports drink. I often get people to rotate through a couple of different flavours, so they don’t get fatigue with that one flavour of sports drink and then even what they do heading in to race day is potentially a different flavour to race as well.


Track body composition change with skin folds, not the scales

I guess with body composition change, particularly with athletes, try not to use a scale as your measure for tracking that, there are really shit measure of body composition change. Because the scales fluctuate all the time based on your hydration status – whether you’ve drunk more or less. How much stuff is in your gut – how much food and bulk you’ve eaten through your whole gastrointestinal system. How much fibre you’ve eaten and that can bulk up what’s in your colon too so that can change. Plus, fluctuations with hormones across the month for females, our weight can change by 1-2kg just with hormone issues. And then you’ve got how well you’ve slept and a whole heap of other factors.

So the scale number is really not a good indication of what’s going on. I like to track body composition change with Skin Folds. That is a really good way to see what’s actually happening at the body fat level, rather than just a number on the scale. I see often, particularly females, you jump on the scales and the number’s the same and you’d get super disheartened that you’ve been working so hard on training and your nutrition and nothing’s changed. Then you do their Skin Folds, and they’ve dropped 5 or 10mm of Skin Folds. Because they’ve been eating properly, they’ve been able to drop body fat and maintain or even put on a little bit of muscle. So don’t rely on the scales when we’re talking about tracking body composition change.


So the Gold standard for me is a DXA which is a body composition scan once a year for my athletes which measures your whole body in a machine. It’s what you might jump in to if you do your bone density – different scan but similar machine and it tells you how much muscle tissues you are, how much bone tissue you’re made up of and also how much body fat you’re made up of. So, it’s getting a sense for how much of those things you are made up of.

And then Skin Folds we do every 4 weeks and that’s more fine tuning tracking your body composition and it measures the distance in the fold of the body fat that sits outside of your muscle. I’d suggest getting a trained anthropometrist to do that for you. So, look for somebody that’s ISAK accredited. That means they’re trained to the international standard to do Skin Folds properly. So that when you repeat the measure every 4 weeks, you know that that data - there’s always a little bit of noise with any body composition measure, even DXA. But making sure that noise is the smallest level possible so that you can accurately track that change.

Those would be my tips for how to monitor how your body composition is going through Ironman and make sure that you are actually dropping body fat and not dropping muscle. Because I change meal plans based on skin fold results as well. Again, why I do packages, because all of this stuff happens to set you up for success to make sure that your Ironman race day is the best that it can possibly be.

Journey to fitness said “thanks again for sharing, have a wonderful day”

You’re welcome!

They would be my top tips for how to lose body fat during an Ironman training build. Just to summarise quickly what they were:

  1. making sure you eat strategically,
  2. you have a sports dietitian approved meal plan,
  3. you let training drive that change your body composition rather than really trying to chase it. I think that’s important for making sure you lose fat and not muscle,
  4. try to do it earlier rather than later so you’re not chasing your tail in the back end when you should be really just fuelling for performance,
  5. you shouldn’t be race weight all year – I think that’s really important; you should have a bit of fluctuation with your weight but not big ones not like 5-10+ kilos. They should be smaller fluctuations.
  6. Slow and steady weight loss wins the race. It shouldn’t be really fast.
  7. And then also I guess finally, if we’re talking about tracking those changes in body composition make sure you’re doing that with something like skin folds with somebody that’s qualified to do so and not doing it with scales. I’m an ISAK accredited Anthropometrist. I have to do a whole heap of CPD and a number of profiles every few years to keep accredited. I’ve done thousands of skin folds so I’m actually going to do another session on what they are and what to look for when you’re looking for somebody to try and do them for you, so you know that they’re doing it properly.

If we’ve got a bunch of triathletes online and you haven’t got it yet, make sure you download my free Triathlon Nutrition Checklist. It’s a 50-point checklist to see how well you’re nailing your nutrition and I want you to go through it. And if you’re in the Dietitian Approved Crew Facebook group, jump on there and let me know what your number is and if there’s any particular areas that you need to work on or have any questions around like how to do that.

Alright, I might jump off before my voice fails but that’s for joining me! Thank you for asking that great question Burkey. I will see you next week!


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