Harcombe is a diet-book selling charlatan. You can pretty much disregard any advice she gives.
My Carb Sane-Asylum: Zoe Harcombe ~ Credentials?
Besides, the fact that a food "spikes your insulin" is no reason not to eat it. Insulin is a necessary and healthy hormone.
Insulin is NOT the enemy! | Fat Fighting Formula
Insulin…an Undeserved Bad Reputation » Weightology Weekly
“The whole concept of a macronutrient, like that of a calorie, is determining our language game in such a way that the conversation is not making sense." - Dr. Kurt Harris