Ironman Race Weight

sunilshah123

I have an Ironman in mid-August, and I realised on Monday this week that, although I have done loads of training, I have put on weight, which is slowing me down. No point in doing all that training and being heavy for the actual race. I tried to read the forums about weight loss for an endurance event, so I've been super focused on healthy eating this week. So far, so good, healthy eating with my training load is pushing me exactly in the right direction. Going on an all-you-can-eat (and drink) holiday with fam next week.. challenging!!!

misfrances

Heck ya, congrats on the iron man, that’s super impressive. I just completed a marathon and found adjusting my nutrition took a bit to figure out. At the beginning of the training block I gained a bit, I was so hungry all the time but eventually my body adjusted to the increase in activity and I was able to get back into a normal eating pattern. I still focused on calories throughout. Every pound of fat lost equals to about 1.4 sec per mile improvement in race time. So I wanted to cut about 5-10lbs before race day while still ensuring I was fuelling my runs and recovery. Which was a ton of juggling.

This was how I managed calories:

On regular run days (8-12km), easy runs/intervals/hill repeats or weight training days: Ate at maintenance. This is my regular level of activity so didn’t really require more. (1800 calories for my age, gender, weight)

Long Run days and Double run days 18-35km: Added extra 300-400 calories. Mainly carbs during runs. Pretty much consisted of a heavier pre meal and gels. Or a bigger lunch between run sessions. (2,000-2,200) calories for me) These days were twice a week and consisted of 2-4 hours of running)

Rest days: ate a 200 calorie deficit but focus on high protein for recovery. (1500-1600 calories)

I found my weekly average would work out close to maintenance calories so with all the training I would loose 0.25-0.5 of a pound a week. So my weight-loss was more through working out to cause a deficit.

I would eat the majority of my calories before, during and right after workouts. High carbs before and during and high protein after. Tons of water, electrolytes daily, caffeine before all morning sessions.

I ended up being 12lbs down after peak week. I was doing 90-100km weeks during the end. I gained back 5lb during the carb load. But ended up still feeling leaner overall on race day and I do think it helped my time.

My favourite carb pre meals for big block days were white bagels with jam, Carmel rice cakes and peanut butter, I would sometimes drink a high carb drink like Maurtens or nakk but only for long runs to prep for what did eat on race day. Easy run days or intervals I would just have a banana or carb bar. Protein after runs was always a whey shake, or Greek yogurt, or eggs and toast.
Dinners were usually a mix of carbs and protein too, I always made sure there was a meat with a vegetable side. Chicken, steak, pork or salmon. Yams, potatoes, corn of the cob and rice are great carbs.

I didn’t drink much throughout the training block, but I am also a mom of 2 so don’t have many nights out to do that anymore.

I am currently in a bulk session this summer so my diets changed again to less carbs and more protein. January 2026 I’ll be starting another training block for my first ultra marathon so I will probably switch back to high carb then.

If you are doing multiple brick sessions and long bike sessions you may need more days of eating in a surplus. Also not sure of your age, gender or current body fat percentage but that would change your needs.

Good luck on your race, I hope you absolutely crush it!!