Key signs of a nutrient imbalance in the diet may include symptoms like fatigue, poor concentration, and frequent illness. Physical manifestations, such as skin issues, hair loss, or unusual cravings, can also indicate deficiencies or excesses of specific nutrients. For example, a lack of iron might lead to anemia, while excessive sugar intake could result in energy spikes and crashes. Monitoring dietary habits and being mindful of any changes in health or well-being is essential for identifying and addressing any imbalances to ensure optimal nutrition.