The amount of sugar, taurine and caffeine in those things! Funny enough taurine helps the liver and is also used to treat diabetes... how ironic.
It's not the caffeine in these drinks that make you perky (Especially if you drink coffee etc), it's simply the amount of simple carbohydrates (sugars). It spikes your blood sugar level, your body then releases insulin hormone to store excess glucose, which is why you get fat from drinking all this shit.
Limit it to 90g a day boys! A can of coke has about 50g!
Vodka and red bull is for pussies!
I'm such a nutrition geek!