Biological classification groups living organisms based on their shared characteristics, reproduction, mobility, appearance, and functionality. Simply put, it is like a system of filling cards in the library. Each card represents a species and is filled in the order in a folder with other species with the same similarities or characteristics (Khawaldeh et al., 2017).

The blood-brain barrier is a protective layer of cells and blood vessels surrounding the brain and spinal cord. It acts like a filter that prevents harmful substances, such as toxins and germs, from entering the brain and damaging its delicate tissues. The BBB allows only certain substances, like oxygen, glucose, and some medications, to pass through and enter the brain. This helps to maintain a stable and healthy environment for the brain to function correctly.

Brain-derived neurotrophic factor (BDNF) is a protein involved in the growth, maturation, and survival of nerve cells in the brain. It plays a vital role in learning and memory and is critical for cell-to-cell neuronal communication within synapses (Castrén & Monteggia, 2021). In the context of the diet-mental health relationship (DMHR), a healthy and nutritious diet elevates the level of BDNF, resulting in improved metabolic and cognitive health.

The brain’s reward system, involving regions like the nucleus accumbens (NAc), regulates pleasure, motivation, and reinforcement. It’s tied to behaviors seeking rewards and is linked to dopamine release, reinforcing pleasurable actions.

Bulimia nervosa is an eating disorder defined by recurrent episodes of binge eating, followed by compensatory behaviors, such as self-induced vomiting, laxative misuse, or excessive exercise, to prevent weight gain. This disorder is associated with a preoccupation with body shape and weight and can lead to severe physical and psychological complications, including electrolyte imbalances and gastrointestinal issues.