An unhealthy diet can significantly impact mood, as poor nutrition often leads to feelings of fatigue, irritability, and anxiety. Diets high in sugar and processed foods can disrupt neurotransmitter balance and overall brain function. Nutrient deficiencies, particularly in omega-3 fatty acids, vitamins, and minerals, can contribute to depressive symptoms. On the other hand, a balanced diet rich in whole foods supports energy levels and emotional well-being, highlighting the importance of nutrition for mental health and mood regulation.