It's irresponsible to glamorize restrictive dieting without talking in detail about why medical supervision is necessary - not just breezily saying "you get dizzy".

http://www.canyons.edu/offices/health/nutritioncoach/concern... - list of physical/cognitive/emotional effects of restrictive dieting: "decreased resting metabolic rate, loss of lean body mass, changes in brain chemistry that increase appetite, constipation and gastrointestinal upset, sleep disturbance and weakness, feeling cold all the time, decreased sexual interest, depression and anxiety, irritability and anger", etc.

Along with causing physical problems, restrictive dieting can be a factor in developing an eating disorder.

http://health.nytimes.com/health/guides/disease/anorexia-ner... - "Bulimia is often triggered when young women attempt restrictive diets, fail, and react by binge eating" (and eating disorders are perfectly happy to grip men as well).

http://calorielab.com/news/2013/03/26/orthorexia-restrictive... - "there are many individuals who display symptoms consistent with an obsessive-compulsive restrictive eating disorder and have an unhealthy concern with healthy eating patterns."