Chocolate Train Food Art, Brussels, Belgium

On the other hand, the unconstrained consumption of large quantities of any energy-rich food such as chocolate is thought to increase the risk of obesity without a corresponding increase in activity. Raw chocolate is high in cocoa butter, a fat which is removed during chocolate refining, then added back in in varying proportions during the manufacturing process. Manufacturers may add other fats, sugars, and milk as well, all of which increase the caloric content of chocolate.
Chocolate absorbs lead from the environment during production and there is a slight concern of mild lead poisoning for some types of chocolate. The average lead concentration of cocoa beans was a very low ≤ 0.5 ng/g, one of the lowest reported values for a natural food. Lead concentration of chocolate was as high as 70 ng/g for chocolate products and 230 ng/g for manufactured cocoa. 200,000 ng is the WHO tolerable daily limit for lead consumption. Additionally, chocolate is toxic to many animals because of insufficient capacity to metabolize theobromine.
A study reported by the BBC indicated that melting chocolate in one's mouth produced an increase in brain activity and heart rate that was more intense than that associated with passionate kissing, and also lasted four times as long after the activity had ended.