Mark is on a strict diet. he has cut down on fats in order to lose weight. because mark is severely restricting his fat intake, he may be getting lower amounts of . this would directly affect the and normal body functions.

Mark may be acquiring lesser concentrations of vitamins and nutrients, that is, omega-6s and omega-3s. This would directly influence the brain and the usual functions of the body as the body requires adequate nutrients and vitamins to survive. This could also influence the chemical balance in his brain, leading to schizophrenia/depression/or other issues like eating disorders.  

Restricting fats may also result in overeating proteins and fats that result in an overbalance of nutrients, and various other health complications. Not getting adequate fat may also influence bone growth.