The 31-year-old won in seven hours, 49 minutes and 20 seconds after the 2.4 mile swim was pulled for safety reasons and the race was changed to a duathlon.
The race in Cork saw athletes complete a 112-mile bike ride with nearly six thousand feet of climbing before running a hilly 26.2-mile marathon.
This feat of endurance required a new nutrition strategy for Alistair, with fuelling on the bike leg key to maintaining glycogen stores enough to sustain the marathon distance run off the bike.
“I aimed to take on between 60 and 70g of carbohydrate per hour using a combination of energy gels, “Super Carbs’ energy drink and rice-based energy bars.” This equated to over 1,500 calories and 400+ grams of carbohydrate during the ride.
"I then had a Mars bar in transition and picked up two OTE caffeine energy gels and some Super Carbs drink from the special needs drink station at 10k. I topped this up with banana and water from the feed stations on the run route too!"
Hydration was also key with Alistair drinking 2 litres of water with ‘electrolyte tablets the day before containing a balance of magnesium, potassium and sodium. Electrolytes were also consumed within the energy gels and drinks during the bike and run.
With an early 4.45am start, breakfast consisted of a simple bowl of porridge, toast with butter and jam and a cup of tea.
“When I found out the swim was cancelled I had a bit more time so I ate an Anytime Flapjack Bar and drank a bottle of electrolytes to stay on top of my hydration before the bike leg started”.
Alistair consumed a total of 2,234 calories during the race and 573g carbs, approximately 70g of carbs per hour, meeting his fuelling target for the event.
"It was a tough, long day," said Brownlee, who won silver at the 2018 Ironman 70.3 World Championships.
"I'd have preferred a swim to make my day easier. The course just drags on, especially in the second half of the bike.
"I set off on the run and thought I'm not sure I'm going to do it (make up 17 minutes on race leader Bryan McCrystal) I just set into a rhythm and tried to eat up some ground. Until the last 10km I was quite enjoying it, but the last 10k’s weren’t fun as my quads tightened up."
“Energy-wise, I felt fine at the finish and was hydrated enough for the doping control straight after the race so the nutrition strategy definitely paid off.”
Alistair recovered with a protein shake followed by burger and chips in a local Cork pub.
Alistair’s Ironman diet in numbers:
80g porridge with semi-skimmed milk – 600 kcal / 76g carbs
2 slices of toast with butter & strawberry jam – 170 / 36g carbs
Total: 770 kcal / 112g carbs
1x 500ml electrolytes
1x Cacoa Nibs Anytime Flapjack Bar – 250 kcal / 35g carbs
Total: 250 kcal / 35g carbs
Bike – 112 miles, 4hrs 54 mins
12x OTE Energy Gels (in a bottle) 1,008 kcal / 246g carbs
2x OTE Duo Bars – 550 kcal / 80g carbs
1x OTE Super Carbs energy drink bottle – 321 kcal / 80g carbs
Total: 1,579 kcal / 406g carbs
1x Mars Bar – 228 kcal / 60g carbs
Total: 228 kcal / 60g carbs
26.2 mile run – 2 hours 51 minutes
2x OTE Sports Caffeine Energy gels – 162 kcal / 40g carbs / 200mg caffeine
0.5x Super Carbs energy drink bottle – 160 kcal / 40g carbs
1x banana – 105 kcal / 27g carbs
Total: 427 kcal / 107g carbs
1x OTE Sports Recovery shake – 185 kcal / 19g carbs / 25g protein
1x Burger & Chips – 1,000 kcal / 100g carbs