Just to burst a myth amongst the 'science': white sugar is not a direct cause of type 2 diabetes.
The problem with white sugar is that it is what is known as an 'empty carb' meaning that other than the calories from sugar there is zero nutritional value, your man is correct in saying that energy comes from sugar but this is in the form of glucose that the body has converted and frees into the system over time. A simple sugar will pass almost directly into the system and be used up almost as quickly. This is why it is important to eat foods that will slow down this action saving simple sugars (glucose tabs for me) for emergencies. The body is a lot more complicated than your Aussie friend would have you believe as I think his banana and sugar smoothie would need to be on a drip to sustain him and then only until he graduates to a realistic diet.
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