Hot dogs which are all beef tend to be very high in fat, and unless you routinely eat a lot of dietary fat, that's likely to upset your stomach.
Oscar Mayer All-Beef Hot Dogs, calories 147, calories from fat, 123
Hebrew National All-Beef Hot Dogs, calories 150, calories from fat, 130
Ball Park All-Beef Franks, calories 140, calories from fat 117
You can do a little better on the fat with a reduced fat all-beef hot dog.
Ball Park Lite All-Beef Franks, calories 110, calories from fat 63
Angus Beef Franks, calories 130, calories from fat 90
And you can do a lot better if you choose a hot dog which is not beef but made from poultry. As already noted, you may be sensitive to certain preservatives or fillers, too. But my guess is the fat, since it really does bother a lot of people who eat healthy most of the time.
Maryn, who enjoys Zweigle's pop-open white hot franks several times per summer
