Dr. Robert Lustig, MD, MSL

Lustig's research explains a pattern that pure glucose tracking misses. Fructose, the sugar in soda, fruit juice, and most processed sweeteners, barely raises blood glucose on its own. But it is processed almost entirely by the liver, where it is converted into fat and chronically suppresses leptin, the hormone that signals fullness. A food can look mild on a glucose meter and still be driving fat storage and constant hunger through this separate pathway.

That is why the WI Score does not rely on glucose response alone. Following the dual-mechanism argument Lustig lays out in Fat Chance, a food high in fructose and low in fiber can score poorly even when its immediate blood sugar impact looks moderate, because the liver and leptin effects Lustig describes are part of the same insulin-first picture RealFoods scores for.

Metabolical widens the lens further, arguing that processed food, not personal willpower, is the primary driver of the modern rise in metabolic disease. That framing, examine what the food industry engineered rather than blame the person eating it, matches how RealFoods talks about food choices throughout the site. The articles below apply the same lens to specific everyday foods.

Lustig's background in pediatric endocrinology adds another dimension to his argument. Treating children with metabolic syndrome and early insulin resistance, he saw the same fructose-driven pattern showing up earlier in life than expected, tied closely to the rise of processed food and sweetened beverages in children's diets. That clinical experience is part of why his work treats metabolic syndrome as a single connected condition, elevated insulin, liver fat, and leptin resistance moving together, rather than as a list of separate risk factors to manage individually. RealFoods reflects that same connected view by scoring meals on their combined hormonal impact rather than any single number in isolation. It is also why sugar science, in Lustig's work, is never just about glucose. Fructose's near-total bypass of the normal blood sugar response is exactly the kind of hidden mechanism the WI Score is built to surface, rather than a food's calorie count or glucose reading taken on its own.