There is no doubt that eating a balanced diet is essential for maintaining a healthy body weight as well as appropriate arousal and energy balance, but the details about how the nutrients we consume are detected and processed in the brain remain elusive. Now, a research study discovers intriguing new information about how dietary nutrients influence brain cells that are key regulators of energy balance in the body. The study, published by Cell Press in the journal Neuron, suggests a cellular mechanism that may allow brain cells to translate different diets into different patterns of activity. "The nutritional composition of meals, such as the protein:carbohydrate (sugar) ratio has long been recognized to affect levels of arousal and attention," explains senior study author, Dr. Denis Burdakov, from the University of Cambridge. "However, while certain specialized neurons are known to sense individual nutrients, such as the sugar glucose, it remains unclear how typical dietary combinations of nutrients affect energy balance-regulating brain circuits." Dr. Burdakov and colleagues studied how physiological mixtures of nutrients influenced "orexin/hypocretin" neurons, which are known to be critical regulators of wakefulness and energy balance in the body. Previous research had demonstrated that orexin/hypocretin neurons are inhibited by glucose. Surprisingly, the current study revealed that physiologically relevant mixtures of amino acids, the nutrients derived from proteins (such as egg white), stimulated and activated the orexin/hypocretin neurons. The researchers went on to show that when orexin/hypocretin neurons were simultaneously exposed to amino acids and sugars, the amino acids served to suppress the inhibitory influence of glucose.