Originally Posted by
big chainring
You still must eat. 1600 calories sounds dangerously low if you are doing anything but sitting on the couch.
Yeah. I wouldn't necessarilly say "dangerous" but you will lack the fuel to ride energetically for any length of time. If you're on a calorie restricted diet, and figure you'll burn ~600 cal in an hour ride, you need to eat some of those extra calories before/during the ride. I'll try to eat 300 extra calories a couple of hours before the ride and then 100cal of easily absorbed carbs (AKA sugars) every half hour during the ride. That 100 cal might be in the water bottles, a banana, gels, fig newtons, bars, or whatever.