Attacking a Sugar Free IRONMAN

Posted Chris Ambassadors, Articles

by Vince Sesto
Tri Swim Coach Ambassador

For me, my experiment with cutting out sugar and processed carbohydrates from my diet is over. It’s now become a natural day to day part of life and don’t see any way that I can now go back.

My first IRONMAN was an amazing experience which has left me buzzing, even almost a month after the race. Removing sugar and processed carbohydrates from my diet is definitely working for me when it comes to endurance training and racing, as well as my day to day life.

It did take a little hard work and some trial and error, but overall, consistent training over a long period of time combined with these changes to my eating habits allowed me to convert to being a more efficient and hopefully a healthier athlete.

I am sure that everyone needs to take an individualized approach to changing their eating habits but if it works, you’ll be able to process fat more efficiently as an energy source instead of relying on sugar or carbohydrates. I don’t like to use the term “Bonk Proof”, but the first time you head out for a long ride or run and don’t need to be accompany it with gels or other food, it’s a pretty big change and feels amazing.

The following is a list of the main things that I’ve learned over the past five months while transitioning into a low carb triathlete.

Some People Just Won’t Get It
It doesn’t matter how hard you try, some people just won’t get it. Don’t let this get you down and don’t feel the need to constantly explain yourself. You don’t need to be an evangelist or preacher, even when things are working well for you. On the other hand, some people will see what your doing, see the amazing results and be influenced to try it for themselves. Feel free to give them as much help as you can.

Give Yourself Time to Adapt
You’re going to need time use any existing carbohydrates in your body and allow your body to become more efficient at processing fat as a fuel source. If you have come from an endurance background, this will most likely be easier for you but each person will be different.

I found my energy levels were not bad during the first week, crashed and struggled to even get to training in the second week, and things started to gradually improve during the third. At the start I committed to six weeks before I would rethink my approach.

Cut Out All Sugar and Processed Carbs at Once
Once you know you have things right, you can always add in an occasional piece of fruit or a piece of bread, but if you want to do this, I believe you need to make a clean break. There are some approaches that suggest a gradual decrease where you remove fruit the first week, bread the second, then all grains for the third, and continue until you have cut out as much carbohydrates and sugar as possible, but see this as giving people a way to fall back into old habits.

How Low is Low?
Some people suggest that you need to drop your carbohydrate intake to under 50g a day, but if you’re training hard, you may find that this isn’t achievable. With trial and error, you’ll be able to see what is right for you and most likely be able to achieve a level of between 100g and 150g of carbohydrates per day, which most likely would be a massive reduction from where you originally were, but still allowing you to switch to utilizing fat a fuel source more easily when needed.

Practice Your Race Nutrition
It doesn’t matter how efficient you are in using fat as an energy source, an IRONMAN is not something that you are wanting to be going into without having properly practiced for, especially nutrition. This includes what you plan to eat for breakfast on race day and the night before. My race nutrition consisted of an omelette for breakfast, nuts during the first half of the ride, then nut butter during the second half of the ride and run.

Be Prepared for Nutrition to Fail Occasionally
With any nutrition, there are always variables that are out of your control that may end up causing your race day nutrition to fail. On race day, I swallowed a nut butter sache in the transition area when I left for my run, I felt nauseous after that and knew that I was not going to be able to continue using them for the rest of the run leg. I switched to diluted coke for the rest of the race with no ill effects.

Using Supplements?
Yes, I use supplements. I take 6g of Omega 3 each day, as it’s been shown that it can help reduce inflammation and can increase the body’s efficiency in converting fat to energy.

I also take a Zinc and Magnesium supplement before bed, as it helps me sleep and can also help reduce cramping. When reducing your intake of carbohydrates, you also need to be mindful that this may reduce the amount of sodium in your body, so I also have a cup of chicken broth on most days.

Some people use ketone supplements, which have gotten some exposure during the Tour De France recently but I don’t have any real experience with them. (

Eat Regularly
Eat three regular meals a day and avoid snacking. You may be excited by the fact that you can go for longer periods of time without feeling hungry, but use this sparingly. Include some fasted training sessions into your weekly plan, but make sure they are not every day as you may send your body into starvation mode where your body thinks that it needs to start storing fat due to there being no food available.

Occasionally Count Your Calories
I don’t think that it’s necessary to count calories, but I do think that, from time to time, it may be worth counting your calories over a three-day period, just to make sure you are still on the right track. It may give you an indication that a recent change to your diet is making a major change to the amount of carbohydrates that you are taking in daily.

I would have loved to be racing my first IRONMAN in my home city, but New Zealand turned out to be a great place to race my first event.

The mass swim start and calm conditions turned out to work in my favor, with a strong exit on to the bike course. It was evident that I still have a long way to go with my bike leg but held firm and stuck to plan even after having about 200 people ride past me. It was all worth it in the end though as I was able to run strong on the picturesque three lap run course, with the local support cheering everyone on.

I just need to work out where my next IRONMAN will be.

See the following link if you are interested in results: