We are adaptation executors, not fitness maximizers: http://lesswrong.com/lw/l0/adaptationexecuters_not_fitnessma...

Also, evolution doesn't care about life span, beyond what is necessary to ensure the survival of genes across multiple generations.

First of all, sugar isn't bad, it's bad in the quantities we generally eat it in modern diets. People also generally don't recognise that sugar you put in your coffee is pretty much the same as the carbohydrates in your pasta.

Evolutionary wise, in palaeolithic times sugar was probably very rare (you'd come across a bush of fruit every now and then perhaps but not all the time). Sugar is something extremely beneficial for your body if there's a lack of it in your diet and you're in a daily survival situation, it's pretty much pure energy. So evolutionary wise, when you come across a patch of sugary fruit it's beneficial to eat it all!

Nowadays we're surrounded by sugar and our diets are saturated with it. The food industries are advertising lies to us all the time. Seen those green cans of Coke with 'healthy' sugar in them? Pretty much complete bullshit!

It was scarce, and starvation was more common threat than diabetes.

Also evolution doesn't care if you are happy, healthy, live long, etc. It only cares how good are you at spreading your genes. We only live long because grandparents make kids more probable to live long enough to procreate.

I think it's because our ancestors didn't have easy access to food in the way we do now. Our bodies are wired to consume and store energy which are necessary for survival in times of starvation.

Evolution is "supposed" to make the genome live longer. Managed to recreate? Cool. You've served your evolutionary purpose.

You could apply this argument to anything addictive, such as smoking...

it isn't bad for us at normal levels of modern consumption