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Thank you all for the caring and helpful replies.

Quick, chart-type summary
periactin, probiotic diet with acidophilus
problems with absorbing fat might mean gall bladder trouble
drink Ensure (2)
Ensure chocolate fudge bars
small but frequent meals (3)
avocado (3) or nut butter (1) is sometimes easier than more processed
fats
yogurt
frequent small servings of rice
gatorade
carnation instant breakfast
suscatal, sipped throughout the day
milkshakes, ice cream, at bedtime
consult D'Adamo, Eat Right for Your Type
canned or well cooked fruit and vegetables
L-Glutaminine and vitamin K
Boost (soy) (3)
Fattening snacks, enough sleep
http://forums.delphi.com
and, the grand winner advice, CUT BACK ON THE SUGAR

So, I went and analyzed my calories and discovered that the refined
sugar, while excessive in and of itself, was nothing compared to the
fruit sugar.  I've started snacking on tortillas rather than fruit,
increasing slightly the amount of rice in a serving.  It seemed to be
helping until the day I gave a birthday party for seven eight and seven
year olds and sort of forgot to eat much of anything - but that only
happens once a year!  Even that day, the feelings of bloat, gassiness,
excessive fullness were MUCH less.

Thank you all again - I guess the moral for us slightly underweight folks
might be that although some foods go down easily, they also don't really
stay put long enough to help.

Elizabeth