Every few months, a new "miracle cure" for cancer trends on social media. From superfoods and supplements to extreme diets, the promises are always bold – and almost always misleading.

The latest claim suggests that a 21-day water fast can "starve" cancer cells and trigger the body to heal itself. It sounds simple, even empowering: stop eating and your body will do the rest.

But biology is rarely that simple. Cancer is not a single disease , and metabolism does not switch neatly between "sick" and "healthy." While fasting can affect how our cells use energy, there is no scientific evidence that it can eradicate tumours.

In fact, prolonged fasting can be dangerous, especially for people already weakened by cancer or its treatments.

While fasting can influence metabolism , imm

See Full Page