Sugar's harmful effects. Sugar consumption has been linked to a variety of harmful effects on the human body, including its potential to be addictive and contribute to obesity. Here are some of the ways that sugar can be harmful: Addiction: Sugar consumption can be addictive, as it activates the reward centers in the brain, causing the release of dopamine. Over time, the brain can become desensitized to this dopamine release, leading to a craving for more sugar to achieve the same effect. This c