Okay, first question that I'm answering.
I recently saw a film about the food industry called "Fed Up" and it mentioned how in a study cocaine addicted rats were offered a choice of two different kinds of water. The first kind had cocaine in it and the second kind had ether sugar water or an artificial sweetener. Something close to 90% of the rats preferred the sweeter water, even with their cocaine addictions.
I didn't think this study was true, so I checked around on the internet to be sure and it's true from what I can tell. I'm aware that HP is not always reliable, so I looked around for the source and I found what looks like the scientific paper on it. It seems to check out and I looked at the sources for their information, how the tests was run, and so on.
Below is the summary of the report.
Here we report that when rats were allowed to choose mutually-exclusively between water sweetened with saccharin–an intense calorie-free sweetener–and intravenous cocaine–a highly addictive and harmful substance–the large majority of animals (94%) preferred the sweet taste of saccharin. The preference for saccharin was not attributable to its unnatural ability to induce sweetness without calories because the same preference was also observed with sucrose, a natural sugar. Finally, the preference for saccharin was not surmountable by increasing doses of cocaine and was observed despite either cocaine intoxication, sensitization or intake escalation–the latter being a hallmark of drug addiction.
And right below this is what the conclusion was.
Our findings clearly demonstrate that intense sweetness can surpass cocaine reward, even in drug-sensitized and -addicted individuals. We speculate that the addictive potential of intense sweetness results from an inborn hypersensitivity to sweet tastants. In most mammals, including rats and humans, sweet receptors evolved in ancestral environments poor in sugars and are thus not adapted to high concentrations of sweet tastants. The supranormal stimulation of these receptors by sugar-rich diets, such as those now widely available in modern societies, would generate a supranormal reward signal in the brain, with the potential to override self-control mechanisms and thus to lead to addiction.
Hope this helps.