Food intake is controlled by an appetitive behavioural control system. The desire to eat is generated by a hunger centre in the hypothalamus of the brain. This is switched off only by the satiation centre also in the hypothalamus in response to the stretch receptors in the stomach being activated by the distension of the stomach as it fills with food. Fat receptors have recently been detected in this centre and these will activate the hunger centre if the required fat intake has not been achieved. This explains why Chinese take-away foods cause initial satiation then hunger quickly returns. The satiation centre switches off the hunger centre due to stomach distension, but the fat centres soon switch the hunger centre on again as they have not been effectiviely deactivated.