HIM Nutrition Advice

it really depends a lot on how hard you go, the environmental factors, and your fitness level.

to me, a HIM is pretty serious business w the nutrition. you can definitely cramp/bonk on the run if you aren't careful during the bike phase....

personally I make sure I take in adequate electrolytes, calories on both bike and run. I like Perpetuem for liquid calories, plus GUs/Blocks..

since you are days away, I don't want to recommend anything other than what you have been training with.

whatever you practiced with....don't look too much at what others do...that is how you get burned....

as far as overthinking it...it depends, guys/gals going sub 5 hrs have different demands then 6.5 hr....70.3 distance starts getting up there.  even 5 hr race is a decent amount for the body to be kept in motion. 

personally i take very little nutrition and live off a course in a half iron event.  i hate trying to come up with a big nutrition plan.  gel flask, gatorade and water...tha tis how i train that is how i race. 

Pre race is oat meal, banana, and 16 oz of coconut water(high in Potassium). Then hydrate with a Perpetuem loaded(2 scoops) with 24oz water.

Bike: Two 24oz bottles of 2 scoops Perpetuem, 1 scoop endurolytes, and water.  Then I will have to pick up a bottle at an aid station for anything more.

Run: Gels at out of T2, 4.5 miles, and 9 miles.  Drinking sports drink at each aid station for the first 9 miles.  The last 4 miles of the run, either I got it or not.

As far as the 'what', as others said, do whatever you did in training.

As far as the bottles, my opinion is that the best setup (assuming you are drinking both sports drink and water) is one bottle on the aero bars and one on the downtube or seat tube.  If you are just drinking water, then just one bottle on the aero bars would be my preference, although some bottles on some downtubes or seat tubes have been shown in improve aerodynamics, so that's definitely an option as well.

In general, and especially if it is a warm day, WATER, WATER, and MORE WATER.  As a bonk victim at the HIM distance myself, I can't stress the importance of this enough.  If you're going all liquid, be careful if you're counting on concentrated formulas.  Sports drinks are often optimized in terms of concentration for max efficiency in digesting carbs, so if you concentrating, be sure you're drinking lots of water on the side.  All liquid doesn't mean you won't get dehydrated.  Also, sports drinks (Gatorate, IM Perform, etc.) are not necessarily going to keep you hydrated - you still need water throughout.

Every situation and every athlete is different, as everyone above has stressed, so it's hard to give you specific advice.  But this is one tidbit that is relatively universal, IMHO.

yes but don't deplete your electrolytes...Hyponatremia can occur

Not for your race this weekend (too late to change nutrition), but in the future if you plan to still stick with all liquid, Infinit Nutrition has worked well for me in the past. You can completely customize your drink which is designed to be your entire nutrition, including electrolytes, carbs, protein, etc.

They help you by guiding you through a series of questions (what distance are you training for, do you have GI issues, sweat rate, etc.) and present you with a custom formula you can adjust - flavor, flavor strength, caffeine, up the calories, etc.

I agree with Jamie's advice to stick with water at the start of the run. 

I will add some advice someone told me that has helped me: don't take in anything during the last 10 minutes of the bike. 

Before I started following that rule I was never certain how I was going to feel during the run.  Now I can be relatively certain that I won't have any sloshing stomach problems if I cut myself off before the end of the bike.