Ironman Triathlon Diet Plan

The Eternal Question.

What to eat. Again a lot of people think they need to turn to diet plans to get them through their training. But like training plans the rigidity of this often leads to failure after a short while. An Ironman Triathlon diet plan is best if it is fluid. It’s much easier to understand the basics of nutrition and eat a certain way rather than stick to a ridged plan that could or should last for over 9months! It’s just not feasible to eat that way. So how should you eat while training for an ironman.

Well the good news is, it is quite forgiving. Eating right most of the time, while having the odd breakdown binge is perfectly ok. Given the high volume of training the body is normally somewhere in the calorie deficit area most of the time. But what’s Right?

Sorry as much as I’d like it to be burgers and takeaway food even with the high amounts of training involved it’s not goingburger chicken pops fries to cut it. But not really just because of the calorie content. Which is obviously very high with these type of food. but its also junk calories. The demands of training put large amount of stress upon the body, So we need to be looking after it well. So foods need to be nutrient rich. But again its about eating right MOST of the time. the odd treat is not going to severely affect a hobbyist athlete.

An Iron distance athlete can quite happily eat quite a large amount of food. If the food it of the right quality. For example a 3hour bike ride is worth almost 3,000 Calories, according to That’s more than an average male is recommended to eat per DAY. So on your long Cycling day can you happily eat the calories of two and still loose weight? Well not quite. The problem with long exercise is the body like to fuel it with your limited blood glucose and when this runs out or low performance is highly compromised. So fuelling will need to take place as you ride in order to complete the ride successfully. See my Nutrition and Fuelling page for more info on fuelling long sessions and Races.

The best Diet for me is basically a regular healthy balanced diet. Breakfast, Lunch and Dinner. Extra calories then come as an exercise sandwich, not that kind of sandwich (but it could be!). You eat some additional calories before the workout, approximately an hour before, complete your workout, then have additional calories afterwards.

So what actual food do I eat!








Still though I’ve not said what is the right foods for you to be eating. The problem here is its such a VAST topic with so many variables and a huge amount of debate. It also depends upon your goals. A high carb diet may be great for fuelling an Ironman training plan but it may be sabotaging the weight loss element. But a High protein-low Carb diet may leave you sluggish and prone to Low Blood Glucose (hypoglycemic) which is not a good place to be when training. And for every 100 people who tell you one diet is best another 100 will tell you its not. I could also tell you to eat lots of Fish (You should) but you might hate fish…so that advise is wasted.

Diet is SO personal. What works for one doesn’t work for others. There is current research that this is down to the individual make up of your gut bacteria, but its pretty new research and could still be completely wrong. But its still true we are all very individual in this respect.

Good foods to me are mainly unprocessed wholefoods. foods that you know what animal or vegetable they came from. So buy meat. Chicken, beef, pork not Chicken nuggets, Burgers or sausages. Buy Fillets of fish or whole fish rather than fishcakes or fish fingers. Eat with plenty of veg. Any veg. It helps if you are not fussy as you can eat a wide range. But if you are its time to dig in. There are hundreds of types of veg and there mush be something you like, or a way of preparing it you will like. I’m pretty handy in the Kitchen so intend to post quite a few recipes using all kinds of veg and alternative ways to prepare.

I mentioned Meat, but if you are vegetarian or vegan I think you will already no that choice of diet doesn’t stop you doing anything. Iron distance racing is no different. You need a balance of fat, Carbohydrate and protein. where that comes from is irrelevant.


This is the heart of an Endurance athletes Diet. How much Carbohydrate, how much fat, and how much Protein you need to consume. Again the answer is not completely simple.  The Recommended “normal” approach is :

Carbohydrates: 45-65% of calories. Fat: 20-35% of calories. Protein: 10-35% of calories

As you can see that’s quite a large range of possible Recommended ratios. You are also probably thinking “how do I work out the rations in my food?” Well there is a simple answer as well as some long convoluted solutions. I won’t / Don’t bother with the latter. To calculate Ratios I use : or download the App from Google Play or the Apple App Store. Its is a very detailed and powerful tool. but also very simple to use. And the best part, Its totally free! I’m not affiliated in anyway, its simply the tool I personally use to Track calories and ratio’s. it even works out your exercise calories so you can fuel to compensate.

Back on the Correct ratio’s I intend to write in detail about the diffent types of diets you can employ. By aiming for the guidelines you are on to a good start.

However don’t be a slave. use the Targets as just that, targets. If you go over one day and under another, don’t sweat it. don’t macro analyse things. Its just important to have an idea, not be a saint. Should you have a huge Blowout. again. Forget it. Move on. Success comes from consistency over time. the odd lapse isn’t going to hurt in the grand scheme.

Finally, if you feel inputting things take quite a bit of time, persevere as you only need to do it for SO long until you will get a good feel for they type of foods you are eating and there make up. after that you can scale back the use of the app. You don’t need to log every meal for the entirety of the training cycle.






image By Lillottama – Own work, CC BY-SA 4.0,

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