Cooking Methods Modify the Glycemic Index of Carbohydrate‐Rich Foods: Evidence From a Systematic Review and Meta‐Analysis

ABSTRACT

Food preparation methods markedly influence the glycemic index (GI) of carbohydrate‐rich staple foods, impacting postprandial glycemic control and associated health risks. We aim to systematically review and quantify how common cooking methods influence the GI of staple carbohydrate foods to inform dietary advice and food policy particularly in high‐diabetes‐prevalence regions like Asia‐Pacific. We conducted a systematic review and random‐effects meta‐analysis of 35 in vivo human trials ( n ≈ 580) comparing GI across boiling, baking, frying, steaming, pressure‐cooking, and refrigerated (“cook‐chill”) preparation methods for rice, potatoes, corn, sweet potatoes, cassava, bread, pasta, and lentils. Data were pooled using DerSimonian–Laird random‐effects models, and subgroup analyses were performed according to food type and preparation method. Boiling produced an intermediate GI (63.1; 95% CI 59.2–67.0). Baking (71.5) and frying (72.8) raised GI, while steaming (59.9) and pressure‐cooking (58.7) lowered it. Refrigeration followed by reheating (“cook‐chill”) yielded the lowest GI (46.3). Subgroup analyses confirmed consistent effects across rice, potatoes, bread, and legumes. Cooking practices substantially alter the GI of carbohydrate‐rich foods. Promoting steaming, pressure‐cooking, and refrigeration with reheating as everyday preparation strategies may reduce the glycemic impact of staple foods, with cook‐chill methods showing the largest reductions in GI compared with boiling. These findings have direct implications for dietary guidance in Asia‐Pacific populations, where rice and tubers predominate, supporting behavioral nutrition interventions, policy reforms in school/institutional catering, and the development of region‐specific low‐GI convenience foods to combat rising diabetes rates.