No one-fits-all healthy diet exists
Search on for genes to explain why weight, cholesterol, insulin vary in mice on same food plan

EATING RIGHT Different genetic strains of mice had varying reactions to eating a ketogenic diet (example of foods shown), a high-fat, low-carb diet. The results back up recent evidence that people’s responses to foods may differ widely.
Joanna Alderson/Flickr (CC BY 2.0)