Why can a drink be a poison?
Part of what makes the human body disturbing is how thin the line is between a substance people enjoy and a substance that harms them. Chemically, most alcohols are quite toxic to the human body; ethanol happens to be the only one that should ever be consumed, yet people regularly poison themselves with others [1]. The unsettling part is not that poisons exist, but that the body's own chemistry makes the difference between a familiar drink and a toxin a matter of which molecule is in the glass [1].
This is a fact about vulnerability rather than exotic danger. The same body that processes a familiar substance can be harmed by a near-identical one, which is why the toxicity of alcohols is described as a property of their chemical structure and not simply of dose or intent [1].
Can you be wrong about your own body?
Perhaps the most disturbing bodily fact is that perception of your own body is not a reliable measurement. In body image disturbance, a frequent symptom of eating disorders, patients with anorexia nervosa continue to perceive themselves as average weight or even overweight despite being severely underweight [4]. The misperception comes with severe bodily dissatisfaction and distress, and it is serious enough to be part of the diagnostic criteria for anorexia nervosa [4].
What makes this especially unsettling is how stubborn it is. The disturbance often persists after treatment and is considered hard to treat; medication does not reduce the body misperception itself, and there is no hard evidence that current body image treatments effectively reduce eating disorder symptoms, though newer approaches such as virtual reality experiences, mirror exposure, and multisensory body techniques are showing promising results [4]. In other words, the body you inhabit and the body you believe you have can diverge, and that gap can outlast the treatment meant to close it [4].
Why do some bodies unsettle us?
A different kind of disturbance is social rather than medical. Bodily differences are not neutral facts: in society, some bodies are read as disturbing, and ideas about what it means to be human and to have a human body shape how those differences are judged [2]. The discomfort, on this view, comes partly from the expectations surrounding bodies rather than from the bodies themselves [2].
That framing matters because it changes what counts as the disturbing fact. Rather than a body being inherently shocking, the unsettling element can be the gap between a body and the narrative of normalcy applied to it [2]. The same logic appears in how medicine visualizes the body: the Visible Human Project, which changed how the body is viewed and studied, is described in cultural and theoretical terms, including a moment of disturbance in encountering the body this way [3]. Together these suggest that some of the most disturbing facts about the body are about how we look at bodies, not only about what bodies are made of [2][3].
Sources used in this answer
Buzzed: The straight facts about the most used and abused drugs from alcohol to ecstasy
Most alcohols are quite toxic to the human body, and ethanol is the only one that should ever be consumed, yet people regularly poison themselves with others.
Disturbing bodies–reimagining comforting narratives of embodiment through feminist disability studies
Bodily differences are not neutral facts; society can view certain bodies as disturbing, shaped by ideas about what it means to be human and to have a human body.
The visible human project: Informatic bodies and posthuman medicine
The Visible Human Project changed how the human body is viewed and studied, and the study treats this way of encountering the body in cultural and theoretical terms, including a moment of disturbance.
Body image disturbance in eating disorders
In body image disturbance, patients with anorexia nervosa continue to perceive themselves as average weight or overweight despite being severely underweight, with severe distress, persistence after treatment, and no hard evidence that current treatments reduce eating disorder symptoms.