Phase zero, which is a certain signal but does not necessarily indicate a disorder, is of course excessive exercise and excessive attention to healthy eating (the term "healthy eating" is defined subjectively by the sufferer. Furthermore, it is the excessive use of food supplements (typically protein, but also others) and in the case of bigorexia, the abusive use of anabolics is alarming.

The sufferer devotes an increasing part of his thinking capacity to thoughts about healthy eating and exercise. He seeks information on this topic, reads relevant literature. This topic gradually starts to dominate the conversations.

Over time, the social contacts of the affected person are significantly reduced. He prefers to communicate and meet people who share his values and lifestyle, while distancing himself from former friends who are not close to him or do not understand his changes. This process often leads to loneliness and other social difficulties.

As the disease progresses, the sufferer becomes more irritable and has a low tolerance to stress. Often there are unexpected outbursts of anger, which may be disproportionate to the situation. These emotional outbursts negatively affect interpersonal relationships and increase feelings of internal tension or frustration.

Unlike other eating disorders, orthorexics and bigorexics tend to change their surroundings, promoting their eating style and regimen.

People with disabilities gradually abandon their former hobbies, interests and activities that used to bring them joy or meaning. They begin to focus all their time, energy and attention exclusively on their new lifestyle - planning, controlling and constantly improving it. Everything else recedes into the background.

If the sufferer finds himself in a situation that makes it impossible for him to follow his dietary or exercise rituals, he experiences intense stress, anxiety and inner tension. These negative emotions may be so strong that he or she starts to deliberately avoid the situation - for example, avoiding social events, travel or contact with people who do not fulfil his or her routine.

The sufferer becomes increasingly plagued by intrusive, recurrent thoughts related to eating, exercise or physical appearance, over which he or she gradually loses control. These ruminations become a dominant component of his or her internal experience and can negatively affect concentration, sleep and overall psychological balance.

In advanced stages, the initially dominant form of the eating disorder may change or combine with other types. Cross-diagnoses occur - for example, episodes of psychogenic binge eating, vomiting or other forms of purging behaviour may be added to the overall food restriction. The clinical picture becomes more complex and difficult to grasp.