1.- steroid: any of a large group of fat-soluble organic compounds, as the sterols, bile acids, and sex hormones, most of which have specificphysiological action.

Sentence: Many friends have consume steroids to look muscular.

source: http://dictionary.reference.com/browse/steroid?s=t

2.- Purge: to cause evacuation of the bowels of (a person).

Sentence: A friend have purge yesterday because he felt fat.

source: http://dictionary.reference.com/browse/purging

3.- Binge: a period or bout, usually brief, of excessiveindulgence, as in eating, drinking alcoholicbeverages, etc.; spree.

Sentence: Normally when people are stressed they binge.

4.- Obesity: the condition of being very fat or overweight;corpulence:

Sentence: I meet a guy that eat everyday and as a consequence he have a problem of obesity.

http://dictionary.reference.com/browse/obesity?s=t

5.- Anorexia: Loss of appetite and inability to eat 

Sentence: some times when I don't have appetite I believe I have problems of anorexia.

http://dictionary.reference.com/browse/anorexia?s=t

6.- Bulimia: habitual disturbance in eatingbehavior mostly affecting young women ofnormal weight, characterized by frequentepisodes of grossly excessive food intake followedby self-induced vomiting to avert weight gain.

Sentence: when I was sick I vomit a lot and my parents thought that I have problems of bulimia.

http://dictionary.reference.com/browse/bulimia?s=t

7.- Manorexia: ?

Sentence: ?

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8.- bigorexia: