|Image from Gay Travellers Network|
Both groups have one thing in common: you're going to get cranky; you're going to get irritable; you're going to have irrational thoughts of leaving [the sport you love, your spouse, your job, your hometown]; and you're going to have unexplained aches and pains and feel like a marshmallow. Absent legitimate medical explanations for these, when you're on a bike, the most likely reason is that you are dehydrated and hungry.
When the Training Ride Leader tells you during the safety speech to "eat before you feel hungry, drink before you feel thirsty," that is what he's talking about!
Hunger and dehydration can cause all sorts of symptoms. A wise man (me) once said:
Eat and drink more than you usually do before, during, and after your ride. Having an insufficient store of calories and salt can cause cramping, lightheadedness, nausea, vomiting, depression, anxiety, and the like... [Read my blog post "Eat!" for citations and much more information.]
So follow the ALC guidelines on nutrition and hydration before, during and after your rides. Listen to your body, true, but listen to those voices in your head too! When they start to get irritable: Drink! Eat!