At the start of treatment, some patients notice changes in their energy levels. Some people experience temporary tiredness, drowsiness or weakness, which is usually linked to the body adapting to the treatment and a reduction in calorie intake. Over time, as the body gets used to the medicine, patients often feel better. As they lose weight, many people find they have greater physical fitness, improved stamina and find it easier to carry out everyday activities. However, if the fatigue is severe, persists for several weeks or is accompanied by other worrying symptoms, you should consult a doctor. A specialist can assess whether the cause of the symptoms is the treatment itself, nutritional deficiencies, dehydration or another health issue requiring diagnosis.