Adolescence /ˌæd

dietician , dietitian /ˌdaɪ.əˈtɪʃ. ə n/ noun [ C ]
a person who scientifically studies, and gives advice about, food and eating
disease /dɪˈziːz/ noun
1. [ C or U ] (an) illness of people, animals, plants, etc., caused by infection or a failure of health rather than by an accident
a contagious/infectious disease
a common/rare/incurable/fatal disease
They reported a sudden outbreak of the disease in the south of the country.
The first symptom of the disease is a very high temperature.
She has caught/contracted (= begun to have) a lung disease/disease of the lungs.
Starvation and disease have killed thousands of refugees.
2. [ C ] something that is considered very bad in people or society
The real disease affecting the country is inflation.