I’ve always been struck by the imprecision of how the terms “low-glycemic-index diet” and “low-glycemic-load diet” are used. In theory, these are diets that reduce post-meal blood glucose and their benefits derive from this property. In practice, they often differ from typical diets in multiple ways. If a “low-glycemic diet” is also higher in fiber and protein and/or lower in palatability, calorie density, and carbohydrate, can we really attribute its beneficial effects to...