Cacomorphobia (from Greek kakos meaning bad, and morphoun meaning form) is the fear of fat people. It is commonly triggered through a traumatic experience with fat people, such as getting intimidated or bullied by them in school. Many sufferers think that fat people are evil and willing to attack, while more severe sufferers are afraid that fat people may explode. As a result, cacomorphobes would stay distant from fat people. Despite that fat people are often disliked, it is rare for people to intensely fear fat people. Panic symptoms of cacomorphobia when encountering fat people include a desire to flee and hide, rapid breathing, fast heartbeat, shivering, trembling, depression, and agoraphobia. Medications are often the only way to treat cacomorphobia, however, psychiatrists often avoid these as they may cause side effects like drowsiness and only suppress symptoms. Other methods effective in treating cacomorphobia include hypnotherapy, behavior and desensitization therapies, which modify how people feel and respond to fat people by gradually exposing too fat people via images, media, and then in person.
You can say its kind of fat shaming.