Pre-trip nutrition

Depends on the trip, of course. For up to a week-long trip, I don't do anything different before trips, nutrition wise. I'm also not out trying to 'push' myself, 15-20 mile days are fairly easy and as much as I need to do.

Are you talking about long-trail trips?

For long distance trail runs, I'm pretty particular about what I eat the night before and the morning of the run. In contrast, I haven't found it to make a big difference when backpacking, even for sustained high (25-30) mileage days. The steady pace promotes fat burning over glycogen depletion, and there is ample opportunity for refueling.

I may allow myself to gain a little weight the week before, knowing that I usually drop 5 lb on a typical trip.

Business as usual, for the most part.

The hours or day leading up to a trip, usually involves spending extended time on the road, and my dietary intake once we hit the interstate tends to lean towards the long haul trucker end of the spectrum.

Don't carbo-load because you can eat while you are hiking and don't need to rely on your energy stores (unlike when doing a long run when your intake is limited).

Don't lose weight before hiking because any weight loss entails some loss of muscle mass, and you don't want to start your hike weak.

Don't fatten up before hiking because that would mean more mass for your muscles to move and more stress on your joints. Why make hiking harder?

Just eat normally.

I try to eat more fruit the day(s) before the trip, to build up Vitamin C.
I also try to eat a big breakfast before starting on the trail (I like big breakfasts in general, but time/traffic constraints get in the way).

"Just looking for some opinions on what to eat during the days before heading out on a trip.
I've considered;
Carbo-loading
Eat very little (lose every ounce of body fat to carry less)
Eat loads of fat (extra warmth on my body which doesn't count as base weight!)"

If you are normal weight, I don't think it makes much difference for trips up to around a week or so, assuming you're not doing 25 plus miles/day. That said, I definitely wouldn't recommend eating very little-no sense throwing away potential fuel. I'm on the skinny side, so for trips beyond a week, I try to put on 3-4 pounds over 3-4 weeks to provide extra fuel and a reserve for unplanned situations. This allows me to reduce the amount of food I carry and thus the weight.

Some sort of fried potato and, as a nod to Eugene, readily available at truck stops (plus fast food joints, gourmet food places, etc..). Try not to get too crazy with the road food to keep "intestinal" issues at a minimum.

Also avoid dehydration with water and maybe some electrolyte solution. This past May, I drank some beer meeting some BPLer's (including Eugene) near Santa Fe, then inadvertently doubled my usual coffee in the AM. Slept very sound at the TH but, in retrospect, I should have forced some water though, as I became very dehydrated on the trail.

Big dinner of pasta and chicken the night before, eggs in the morning. Doesn't get much better than that.