Adolescence /ˌæd

depression /dɪˈpreʃ. ə n/ noun UNHAPPINESS
1. [ U ] the state of feeling very unhappy and without hope for the future
I was overwhelmed by feelings of depression.
2. [ C or U ] a mental illness in which a person is very unhappy and anxious (= worried and nervous) for long periods and cannot have a normal life during these periods
Tiredness, loss of appetite and sleeping problems are all classic symptoms of depression.
If you suffer from depression, it's best to get professional help. See also clinical depression
diagnosis /ˌdaɪ.əgˈnəʊ.sɪs/ /-ˈnoʊ-/ noun [ C or U ] plural diagnoses
a judgment about what a particular illness or problem is, made after examining it
"What was the diagnosis?" "Arthritis in both joints."
The doctor has made an initial diagnosis.
Diagnosis of the disease (= saying what it is) is difficult in the early stages.
diet /ˈdaɪ.ət/ noun
1. [ C or U ] the food and drink usually eaten or drunk by a person or group
Diet varies between different countries in the world.
a healthy/balanced/varied diet
Rice is the staple diet (= most important food) of many people in China.
The children seem to exist on a diet of burgers and chips.
2. [ C ] when someone eats less food, or only particular types of food, because they want to become thinner or for medical reasons
I'm going on a diet next week and hope to lose two kilos before Christmas.
a crash/strict/calorie-controlled diet
The doctor put me on a low-salt diet to reduce my blood pressure.
3. [ S ] a particular type of thing that you experience or do regularly, or a limited range of activities
He was brought up on a diet of political propaganda from birth.
The TV only offers a diet of comedies and old movies every evening.