How Does It Work? Nutritional Response Testing is a non-invasive system of analyzing the body to determine the underlying causes of illness or poor health. We treat the root of the issue – not just the symptoms. Nutritional Response Testing allows your own body to communicate where imbalances are occurring and potential causes of these imbalances. Examples of imbalances in the body are weight loss/gain, inconsistent digestion, poor memory, mood swings, irregular sleep patterns and lack of energy.