Common signs of nutritional deficiencies may include fatigue, weakness, and changes in appetite. Specific deficiencies can lead to particular symptoms; for example, a lack of vitamin D may result in bone pain, while insufficient iron can cause anemia, leading to pale skin and increase fatigue. Other signs include hair loss, digestive issues, and weakened immunity. Regular check-ups and blood tests can help detect these deficiencies early, allowing for timely interventions and adjustments to dietary intake.