Glycemic index and glycemic load

The glycemic index (GI) ranks foods by how fast their digestible carbs raise your blood sugar, compared with pure glucose (GI = 100). A GI of 55 or under is low, 56 to 69 is moderate, and 70 or over is high. But GI ignores serving size. So glycemic load (GL) captures the real-world hit: GL = GI × available carbohydrate (g) ÷ 100. High-GI, high-GL meals cause fast glucose spikes and big insulin surges. Over time that promotes high insulin, oxidative stress, and low-grade inflammation. Those processes are tied to insulin resistance, β-cell trouble, and faster biological aging. The PURE cohort (Jenkins et al., NEJM 2021; 137,851 people across five continents) found something specific. In people with existing heart disease, the highest versus lowest GL fifth carried a hazard ratio of 1.34 (95% CI 1.08 to 1.67) for major heart events. In the prevention group (no prior disease), there was no significant GL link. A Weizmann Institute study (Zeevi et al., Cell 2015; 800 people) showed that blood-sugar responses to identical foods vary a lot from person to person. The drivers include your gut microbiome, genetics, and metabolic state. In a randomized follow-up, algorithm-based personal advice beat generic GI-based advice. The 2015 ICQC consensus backs low-GI/GL diets as evidence-based ways to prevent type 2 diabetes and coronary heart disease. It also notes that processing, ripeness, and meal makeup can shift a food's effective GI by 20 to 30 points.

Last reviewed: June 22, 2026

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