The human brain is equipped with centres that simultaneously regulate the sensation of hunger and of satiety. These centres are found in a small gland situated within the centre of the brain called the hypothalamus. These centres are sensitive to blood hormones called neurotransmitters, which exert a stimulating or inhibitating effect on hunger and satiety.

The neuro-mediators are adrenaline, noradrenaline, dopamine, and serotonine. Certain drugs such as the anorexigenes (or "hunger inhibitors") act on the neuro-mediators. These drugs are derived from amphetamine and increase the release of dopamine and adrenaline in the area where hunger is regulated, leading to the suppression of the latter.

The flenfluramines in turn increase the release of serotonine where satiety is regulated, thus stimulating it.

->> All mediators constantly interact, leading to an extremely fine-tuned regulation of the appetite and satiety for each individual, which is closely linked to their individual calorific needs and physical activity.