Pretty much agree with the trend here, Skratch is good for electrolytes but one needs calories too. I never thought Skratch had enough frankly. But its easy to add this. Gels, honey waffles, etc., is a good start. The extra sugar (glucose) often aids in hydration as water is absorbed more efficiently into the blood and body.

Couple things.

While what others have detailed is true - skratch is light on calories - it doesnt mean it can't be used as a calorie source. Especially in a race like Kona where the hydration needs will be heavier than in more moderate temps. More fluids, and more fluid mixed with skratch, means more calories. So yeah 80 calories in a 16 oz serving isnt enough to fuel you, even if your hydration needs call for 32 oz in Kona like conditions. But Lim doesnt balk on slightly concentrated mixes. Personally, I've had success using slightly concentrated bottles of skratch - roughly two servings in a 22oz bottle (160 cal/22oz). So if my hydration requirements were around 32 oz for a race like Kona, I could theoretically be getting about 230 calories from Skratch alone. Then, you could supplement with additional simple carb sources (not malto/carbopro) to make up for the gap in calories. But you'll also find that being well hydrated in hot/humid races, is much more important than being properly fueled. So 230cal/hour with 32oz of fluid/hour might just be enough.

In practice, it could be hard to execute that option on race day though. You'd definitely need three bottles on your bike to start and then you'd need refills at special needs. Doable. But maybe not ideal.

The other option would be to run a more concentrated bottle of skratch and supplement with on course water - maybe a 600 cal bottle to start and then another at special needs for a total of 1200. The strategy here would be sip water, sip concentrate, sip water. Skratch works because it has a low osmolality (read more about it here: http://blog.skratchlabs.com/...science-and-practice). There's no secret sauce to skratch - its a simple 4% carbohydrate solution with the necessary amount of electrolytes. And more sports nutrition companies are now copying Lims formula essentially. This concentrated skratch bottle would increase the osmolatlity of the solution significantly. Which means its very important to dilute each sip with water. This can mean more room/opportunity for user error. Because if you don't dilute the solution with added water with each sip, you'll end up with the gut rot you've suffered from while using CarboPro.

The problem with CarboPro is its essentially just maltodextrin. Malto already has a higher osmolality than the more simple carbs used in skratch - but through some fun chemical processes that happen during the attempted digestion of malto, it becomes even worse. Which for most people, wreaks havoc on the digestion system - let alone the digestion system while under the stress of racing. Sure, malto is an easy way to load up on calories. But if the actual calories you're consuming prevent proper digestion, its as if you didn't even consume them in the first place. Your gut rot issues are just that. Under stress, like exercising/racing, your body is tasked with a myriad of other internal processes that its not tasked with while at rest. The blood that would be used to aid in digestion of those calories you just consumed is being rushed to other areas - primary of which are the areas of the body that aid in cooling. You can see how this becomes even more important in conditions like Kona. Its imperative that you're consuming calories and fluid that can actually be absorbed WHILE racing.
'
The last part not yet touched on is the importance of electrolytes for all of this. Think of electrolytes as the tiny taxis ferrying all the fluid you've consumed across the cellular membranes of your stomach/intestines to be absorbed into your body. Electrolytes assist with hydration. The Magic Johnson's of the fluid absorption process. This is why drinking only water is a very bad idea. Again, theres some very interesting and complex science behind all of this that I dont pretend to fully understand (though do find quite fascinating). The takeaway is that you need electrolytes and I'm of the opinion that more is typically not a bad thing - under the premise that you'll piss out what you don't need.

The final thought is that science can say one thing - but you'll find examples of others who succeed or have success with strategies that science says shouldnt work. And thats why anything that you try should be tested and retested. Simulating as close as possible to the environments you intend to use them in.

Last thought. I love gluten. Pasta, bread, etc. But I remove all types of gluten in the 48 hours before a race. Most of the reading I've ever done on the subject of race nutrition/nutrition in general appears to agree that gluten is a stomach irritant for everyone to some extent. The last thing I want to do leading into a race is irritate my stomach considering I need it to be primed and ready to absorb everything I consume on race day. So as a general rule of thumb, I advise any athlete I've worked with to at least try the same.

---

"One Line Robert"