It is impossible to compensate for a poor diet with physical exercise ("You cannot outwork a $hit diet"); a mediocre diet causes invisible internal damage despite a deceptive outward appearance.

noli's read

The principle that exercise cannot cancel out the metabolic effects of a low-nutritional-quality diet is widely supported by research. Meta-analyses (e.g., Journal of the American College of Cardiology) confirm that metabolically healthy obesity is a transient state and that nutrient quality impacts cardiovascular health independently of weight. It is accurate that physical exercise, while crucial for metabolic and muscular health, has a limited caloric impact compared to the energy density of certain ultra-processed foods. The claim regarding "internal damage" is scientifically grounded: a diet high in added sugars and saturated fats promotes systemic inflammation and insulin resistance, even in thin or athletic individuals. The idea that some appear to "get away with it" due to genetics or performance-enhancing substances is a common clinical observation. The advice is therefore robust, although it simplifies the complexity of the interactions between metabolism and exercise.

the sources

No named source held this one up — that absence is part of the verdict.