Birtwhistle, who has this week been training in New Plymouth with team mates, Olympic Team nomination Aaron Royle and Australia's top placed international triathlete Ryan Bailie, admitted his pre-race nutrition played havoc during the UAE heat in the World Triathlon Series opening round a fortnight ago.
Birtwhistle and Royle, who has already claimed an automatic Olympic Team nomination for Rio, will be among a strong field of Australians – 16 in all – who will line up in the combined Elite/Under 23 field – against 11 New Zealanders with the winner securing his country a guaranteed third quota spot for this year's Rio Olympics.
It will be the same in the women's race with the winner of the combined Elite/Under 23 Oceania Championship securing that all-important wildcard position as both countries look to a maximum of three men and three women for Rio.
Dual Olympian Emma Moffatt, who is well up the Olympic points totem pole with a host of Australian girls, heads the small Elite field who will bolstered by Under 23s Jaz Hedgeland, Emma Jeffcoat, Laura Dennis and Holly Grice.
Moffatt began her campaign for a third Olympic team with a fast finishing second place to Commonwealth Games gold medallist Jodie Stimpson in the Mooloolaba ITU Oceania Cup Sprint last Saturday and is looking forward to this week's Standard Olympic distance.
And for Tasmanian-born Wollongong-based Birtwhistle his race-day diet has left him with some food for thought.
"ln Abu Dhabi l took on too many carbohydrates pre race and my body couldn't handle it in the heat," admitted 21-year-old Birtwhistle.
"It's frustrating that it is such a simple thing that I have only just learnt, but I'm glad I have learnt it early in the season.
"I started to feel sick from the warm up and this continued throughout the entire race.
"It was annoying to have come so far, but still only learning the basics of how my body works in certain environments.
"Fortunately though, I learnt this at Abu Dhabi and not on the Gold Coast in one month's time where it will likely be warm again.
"I can put it past me and move on with the year ahead and things seem to be going well leading into Gisborne this week.
"The squad has settled down here in New Plymouth (where they will spend the next month) and we have put in some quality training since Abu Dhabi, so things are looking positive."
Birtwhistle was 39th in Abu Dhabi, one place behind New Zealand Under 23 representative Sam Ward who was also 24th in the Chicago World Championship race won by Birtwhistle last year.
The pair, who have raced right through their Junior and Under 23 careers together, will again line up in the Oceania Championships which will be run in conjunction with the Elite Men's race with that guaranteed quota spot on the line.
The winner must still fulfill their National Federation's individual selection criteria with Australia's Shadow Squad chasing the final automatic Olympic Team nomination with a top ten finish in the next WTS race on the Gold Coast on April 9.
Royle, who opened his Olympic campaign with a solid fifth placing over a sprint distance Oceania Cup race in Wollongong earlier in the month will spearhead the Elite Australian group of Ryan Fisher, Cam Good, Tim George and James Thorp while Birtwhistle will headline an exciting group of Australian Under 23s, Declan Wilson, Marcel Walkington, Matt Baker, Luke Willian, Dan Coleman, Brandon Copeland, Joel Tobin-White, Matt Roberts, Charlie Quin and Kane Edwards.
Walkington has already secured his automatic selection in the Under 23 team for the ITU World Championships in Cosumel, Mexico in September – the others will be out to earn their places.
The cream of Australia's juniors will also line up for the Oceania Championships with defending champion and 2016 Australian Junior Series leader Matt Hauser at the forefront of the Australian group along with training partners Kye Wylde and Jack Van Stekeleburg and the likes of Jack Tierney and first year junior Lorcan Redmond.
The Junior girls will see Series leader Sophie Malowiecki joined by Youth Olympic champion Brittany Dutton, Australian champion Kira Hedgeland, Jess Claxton, the Hoitink girls Grace and Ellie and the Leahy sisters Elle and Zoe amongst a host of emerging Australians.
Saturday's 19th March Race Schedule (NZ times)
9.00am Junior Women Sprint (750m Swim / 20km Bike / 5km Run)
9.02am Junior Men Sprint (750m Swim / 20km Bike / 5km Run)
1.00 pm Elite and -23 Women (1500m Swim / 40km Bike / 10km Run)
4.00pm Elite and -23 Men (1500m Swim / 40km Bike / 10km Run)
Sunday 20th March 2016
11.00am Junior Mixed Team Relay (300m Swim / 8km Bike / 2km Run)
Gisborne Sydney Brisbane
9am 7am 6am
11am 9am 8am
1pm 11am 10am
4pm 2pm 1pm
IMAGES Credit: Delly Carr | ITU Media