Does taking on carbs in-ride reduce potential fat loss?
It's a really good question. I think the short answer is 'yes' but I have to admit I don't really know. I think it's complex, and a detailed answer would require knowledge not only of your body chemistry but also of the processes involved.
On a hard ride (a sportive for instance), clearly you need to fuel and replace glycogen stores pretty quickly. So that points to fast acting carb. And yes,generally speaking, consuming fast carbs does lead to insulin spikes and associated fat storage (imho
).
I think part of the problem (if you could call it a problem) is that we are not designed to be endurance athletes. We have minimal stores of glycogen that's best use is the short and intense effort. We're not built to do that over and over again over a period of hours. So on bike fuelling becomes a necessity. I think it's simply a compromise you have to except if you want to ride hard and/or long. Further, I believe that if weight loss is your prime aim, and you're serious about it, then DON'T exercise hard. Obviously, intense exercise has many, many benefits but I just don't happen to think it's conducive to loosing weight.
Obviously, a great deal depends on your levels of intensity. And clearly on the type of riding you want to do. You can keep your effort levels down on 'slow burn' long rides, and require little (or nothing) in terms of fast carb refuelling, but that's not much help if you want to work hard. The long, slow burn ride is still useful though if your aim is training to ride hard. It coaches your body to burn fat in preference to carb, preserving glycogen levels for when you need them.
I recall reading Sean Yates saying that back in his riding days when fuelling wasn't as well understood as it is today, the bonk (whilst not aimed for) was advantageous to the rides that followed. Riders felt supercharged after it. Basically, the bonk had given the body a crash course in carb deprivation. In the rides that followed, the body seemingly better protected the glycogen levels - so they were available when really needed (and riders were empty).
For the athlete that has accepted the need for on-bike fuelling via fast carb, the question is how to manage it. And here you need someone more knowledgeable than I! What I think you're aiming for is to consume only what you'll immediately burn. Trying only to keep the glycogen stores topped up and not overdosed. My naive belief is that this minimises the 'fat storage' effect of excess fast carbs. How you calculate the exact amount you'd need to take is where I've no idea! Sorry! But I think you have to accept that it IS compromise and not view your riding in weight loss terms.Weight loss is something you do via diet and not on the bike.
Personally, I don't ride that hard so I don't require that level of sophisticated calculation. I'll happily ride 100km at an average of maybe 20-22kph on only a banana or fig roll. I'm going to be riding a sportive in April time, and for that I accept I'll probably use gels or somesuch. My aim then will be to keep to a minimum; a gel an hour sort of level.
But you said what I was trying to :P
