A tub of B&J choc fudge brownie ice cream contains a little over 100g of simple sugars. Even allowing for the buffering effects of the accompanying fats, that is a lot of sugar to be dumping on the body in one hit.
I would guess that that 100g acts upon blood sugar levels rather more decisively, rather more diastrously if the base level of blood sugars is low, or we might better say, appropriate (if somebody is not eating sugar every couple of hours).
This might suggest (for the rosacean concerned about flushing but not for general health!) that if you are good you must be consistently good and that if you are naugthy it doesn't much matter if from time to time you are very naughty.
It's good that you are enjoying your juices! As you imply finding alternatives to coffee is difficult; finding warm alternatives to coffee harder still. I find herbal teas and whatnot pretty tastless but have happened upon lemon flavour granules which are more toothsome (though about 80-90% sugar!). It tastes exactly like Lemsip, if anybody is interested.
