I think many people are very confused about cortisol. I'm probably among them, but here is what I've learned.

As far as I can tell, cortisol is released in response to stress, not in response to low blood sugar. Yes, one of the things it then does is stimulate gluconeogenesis, but that doesn't imply that cortisol is released whenever you are running out of glucose. In normal circumstances glucagon takes care of that.

So I don't really see the point in eating starch to try to somehow mitigate cortisol. If cortisol is released, it is released, and it's going to do what it does. How does eating starch on top of that help? If cortisol hasn't been released, then glucagon will take care of your blood sugar.

If you have cortisol issues, you need to avoid going for too long between meals, make sure your sleep is restful, and limit caffeine and alcohol.

As far as intense exercise goes, personally, I can do it just fine as long as my calorie and protein intake are adequate. But my hunch is that a small amount of starch before or after the workout won't actually hurt you, because it is going to get used so quickly.

If you workout intense enough you can avoid the cortisol. warmup plus eight fourty second sprints with 2-3 minutes in between will finish in about 30 min. That is more than quick enough to avoid cortisol. This 3 times a week plus a leasurly run on another day is what I do.

The recomendation to eat carbs post workout is something that coaches teach their athletes so that they can recover faster. Two varities. Whey protien with a simple carb or a glass of chocolate milk... (Now this advice is the advice of coaches that may or may not be paleo) I mention this to give context. The brief insulin spike allowing the protien to be absorbed into the muscles.

However another effect of the simple carbs is that it kills HGH.

I don't know the science behind it, but if I either fast or eat only protein and fat after a fasted workout, I feel that it takes longer to recover and my muscles are sore for longer. I also feel unsatisfied and have the munchies, which is unusual. If I have some carbs, not much, such as a banana and a glass of whole milk, after workouts, it feels fantastic.

This is more true after intense workouts (sprinting or weights) and less so for jogging, but still true all the same.

Other than that I eat a pretty low-carb diet, really nothing starchy at all, some carbs from dairy and red wine, and the occasional blueberries.

I have not really pushed it though. I could try to "train" myself to adapt to fasting or eating only protein after workouts. I really noticed a big difference when having even just a half a banana after workouts, so I'll probably stick with it. Some fruits and starchy vegetables (i.e. sweet potatoes) are great sources of certain nutrients, so my thinking is that this is not a bad way to get them.

Glycogen is depleted in intense workouts and carbs are what "restock" the glycogen supply. In order to burn fat for energy, glycogen is needed. The best way to have this happen is to "re-feed" immediately after a workout. It doesn't have to be a lot, half a sweet potato, a piece of fruit etc.

I don't know about the effects of longevity, but if feeling good and looking good and performing well are important, I'd re-feed with some carbs immediately following a workout.