Specific nutrients consumed in the individual’s diet form the brain’s chemical composition since nutrients are the precursors of neurotransmitters, which affect the brain’s functioning. These chemical molecules are transmitted from one nerve cell to another through nerve conduction. Depending on the level of these messages, mental health, mood, sleep patterns, and thinking capacity change. Therefore, the nutrients consumed affect mood, behavior, and brain functions. The brain has intense metabolic activity and uses 20–30% of the daily energy intake, even at rest. Changes in the energy and nutrients taken into the body affect the chemistry and function of the nerves in the brain. The relationship between nutrition and mental state is two-way. While a person’s diet affects their mental state, their mental state also affects their nutrition. Emotional state affects which food individuals consume. In various studies, most participants said they changed their diet during stressful times. In a stressful situation, the individual looks for foods that will help them relax quickly. However, it should not be forgotten that this can lead to a vicious cycle; foods high in carbohydrates can cause drops or increases in blood sugar accompanied by surges in adrenaline or epinephrine, commonly called the ‘stress hormone.’ Accordingly, high consumption of refined carbohydrates and sugars can worsen the stress response. The relationship between food and mood can also work in the opposite direction. Namely, the foods consumed can also affect mood. There is a view that there may be foods that make one more resistant to stress.