Been bumping up my time in the saddle these past couple of weeks, and it occurred to me this evening that I'm probably not eating enough. After a moderate to quick 1.5 hour ride yesterday I felt really lethargic today and I couldn't figure out why, but I'm wondering if it's because I should be consuming more calories to improve my training. My Strava suffer score was 46 based on heart rate zones built from LTHR and the related recommendations from Friel and Coggan, so it's not like it was a hammerfest in the slightest.
For reference, I'm around 187 centimeters tall and weigh about 72 kilos, and currently have a 75 centimeter waist. So I'm reasonably slim but I wouldn't call myself skinny. I feel like I eat normally; a bowl of cereal for breakfast, some larger meal during lunch, and then whatever I happen to eat for dinner. But maybe that's not enough? My goal is to be maximizing recovery so I can put in the high-volume zone 2 work I'm going for right now.
How do you tell?