Congratulations on both your weight loss surgery and taking on the 26.2. Obviously, I can’t give you any medical advice…However, I can share my experience. “Carbing up” for runners is considered a little bit of a myth by now. The principal of carbo-loading is no longer widely accepted. Most nutritionists recommend a normal balanced diet for everyone – including marathoners AND those post-weight loss surgery.
However, I assume you mean fueling during your run. Being close to seven years post surgery, I no longer have capacity issues that prevent me from consuming enough liquids. What I can share is some insight on how I fuel during runs.
I have tried a variety of products. I have “experimented” with a large number of bars, gels and drinks. My favorite is POW (plain old water). Aside from that, I found as long as I use it during a long run, Gatorade seems to work fine for me. I also drink some before and after vigorous workouts. I have also tried quite a few products for fueling. The two I seem to like are GU (the original energy gel) and “Sports Beans”. Sports beans are electrolyte-enhanced Jelly Beans. These seem to work since I can grab one at a time slowly. I also use a capsule-based product called “endurolytes”, which is an electrolyte replacement capsule. You also want to be careful with some of the commercial products as some of them contain caffeine, which may have undesirable effects.
I would suggest you experiment with some various products and find what works for you and carry it with you in your race. You might want to also see what sports drink is on the course for your marathon. For instance, when I ran the Disney Marathon, they had Power Aide, which I find I cannot tolerate at all.
Finally, I would suggest that you don’t significantly vary your diet before race time since this may result in undesirable digestive side effects.
So I would say, as post-weight loss surgery patients, we are more sensitive to digestive issues related to refueling products as well as caffeine. So, bottom line, I would suggest trying a few different things and testing them all before your race. A good place to obtain different products and samples is at another marathon in your area, the number pickup usually has an expo where vendors of this stuff offer samples as well as opportunities to purchase products at a reduced cost. These expos are usually open to the general public even if you are not participating in that race.
Good luck with your training and your race. If you have any more specific questions, you can e-mail me at firstname.lastname@example.org.