It's just 300 calories less that your body will use from previous fat stores, but you will still get fasting benefits. If you want to drop more body fat faster, use less creamer.
I've been combining ideas from Leangains with my Primal way of eating/living for a little while now, but certain questions eat at me. For example, I try to do my daily workout (strength, bike ride, hike, whatever) in a fasted state each day. Ideally, I will rise at 8:30, exercise by noon, eat at about 2pm. I usually try to keep my feeding window between noon and 10pm. The Leangains dude says not to worry about a splash of milk in your coffee or tea, regarding calories before working out fasted. I tend to use heavy cream in my coffee (2 cups usually) and taht can add up calorie-wise.
So, what actually DO the calories from the cream in my coffee do to detract from the effectiveness of my fast? To what extent does that hinder the benefits my body gets from the fasting? I have to guess that I my get 300 calories from a morning of coffee creamer......i use a lot.
I have two cups too, but much less cream. Maybe about 100 calories worth. I say that if you enjoy your coffee that way, and you are making gains in strength and losses in fat, then keep enjoying your cream.
Lean Saloon guy agrees with you that using a little cream during your fast does virtually little damage to your fast.
As a former "few cups of coffee w/ heavy cream" a day person, I think that the hardest thing about Leangains style fasting has been giving up my morning coffee. Especially when i sit across from my Mother (she's my business partner) all morning, and she's drinking this huge cup of coffee. Makes me super jealous.
Regardless, as the days and weeks went on I realized I needed it less and less.
Recently, I've started adding a tiny cup of coffee back into my morning schedule. I used to drink huge cups, but in the AM now I'll have maybe 1/3-1/2 cup of coffee with a TB of Mimmiccream (I've also given up dairy...another thing I "never thought I could do"). This hasn't seemed to have affected my fasting/results, and to be honest it brings me great joy!
So instead of either depriving yourself or feeling guilty, my advice would be to try a smaller cup, or at least one cup, and see how it goes! I honestly don't think a small amount of calories will do anything - but I echo the statements of others in saying that you should probably try and keep it under 100 cal during the fast. Johnny from Leansaloon and Martin both say that those calories will just deviate your body from burning fat for the amount of time it takes to burn those calories in, so it shouldn't disrupt the fasting benefits for too long!
Haha and PS - I'm someone who appreciates a good milky-colored cup of coffee - the more cream the better . If someone ever suggested to me to try my coffee black I'd slap them across the face