If I marinate tofu or chicken, how do I know how much of the marinade are soaked up by the food?
I have an oil based marinade I love, but the oil makes it really high in calories. I know I throw most the marinade away, but the amount that stay with the food I think would have a significant difference.
Don't worry about it. Are you overweight? If not, and if you have been eating that marinade and are healty, you shouldn't stress over it. Eating also needs to be pleasant. And it's the fatty french fries and dressing-soaken salads people eat with the meat that make the difference. If you need to, I suggest you try reducing fat intake somewhere else ;)
Maybe measure how much marinade you made, how much is left over, and subtract the amount? That's the only thing I can think of.
Have you tried making the marinade without the oil? The only thing the oil in marinade does is keep things from drying out as much, so if you kept a careful eye on it, you might not need the oil, or maybe not as much. I agree with livelaughdrawx - if you want to use the marinade without changing it, then measure before and after, and write it down somewhere. Then you'll have a good idea for future use just how many calories that marinade adds.
A nutritionist friend of mine advised me years ago that for a paste type marinade (eg pesto) assume 1 tbsp of the marinade sticks to each 85 grams (3 oz) meat.
For a oil based liquid marinade, assume 0.5 tbsp of the marinade sticks to each 85 grams (3 oz) meat.
For a non-oil liquid based marinade (eg juices or wine etc) assume 1/3 tbsp sticks to each 85 grams (3 oz) of meat.
I hope this helps.