How long can I live on lettuce alone?

I’m a 33-year old male, 5’10" and 165 lbs.
If I had to live on only iceberg lettuce and water, how long would I last?

My friend and I have a bet riding on this. There are probably no empirical examples of this so we’ll evaluate any rational explanations and determine which one of us is closest.

Iceberg lettuce is pretty much just water (90%) and cellulose. Almost no nutrients or calories. Low enough so that a quick Google search doesn’t even list them. Loose-leaf lettuce, which is much more nutrious than Iceberg lettuce, has 19 calories in a 52 g (1 cup) serving ( So even for loose-leaf lettuce, you’d have to eat about 100 cups (5 kilograms) in a day, just to maintain a decent caloric intake. I’m guessing that with Iceberg lettuce, you’d actually run a caloric deficit processing it.

So on an Iceberg and lettuce and water diet, you’d last roughly as long as you would on a purely water diet. Maybe a bit less, although the fiber would at least help to diminish the hunger pangs. How long is that? Based on David Blaine’s recent stunt, you’d could last between 3 and 8 weeks under ideal conditions. Here’s a site that actually backs up my WAG with some facts and a list of the damage you’d do to yourself in the process (