Postprandial glycaemic response to white and wholemeal bread consumption between normal weight and overweight/obese healthy adults

Obesity and the increased postprandial glycaemic response (PPGR) are risk factors for type 2 diabetes. Few studies have explored the association of body weight with PPGRs. The study aimed to investigate the PPGR between healthy adults with normal weight and overweight/obesity to two commercially available breads (white and wholemeal) with different dietary fibre contents. In this acute randomised crossover trial, 20 healthy adults (10 normal weight, 10 overweight/obese) consumed two slices of white (100 g, fibre 3.6 g) or wholemeal bread (88 g, fibre 5.6 g) alongside 150 ml of orange juice and 10 g butter on separate visits in random order after fasting for 8-12 hours. The blood glucose concentration was measured fasted, 30 min, 60 min, 90 min and 120 min postprandially by finger pricks. Information on age, gender, ethnicity, body mass index (BMI), and body fat percentage were collected. Two-way repeated measures ANCOVA was used for controlling for age, gender, ethnicity and body fat percentage, and results showed no significant difference was observed in fasting blood glucose concentrations (F(1, 14)=2.968, P=0.107), incremental areas under the curve (iAUCs) (F (1, 14) = 0.702, P=0.416) and peak values (PVs) (F (1, 14) = 0.507, P=0.488) between participants with normal weight and overweight/obesity, or in fasting blood glucose concentrations (F(1, 14)=0.007, P=0.964), iAUCs (F (1, 14) = 0.008, P=0.929) and PVs (F (1, 14) = 0.036, P=0.851) between white and wholemeal bread consumption. The BMI or body fat percentage was not associated with iAUCs or PVs regardless of bread type adjusted by age, gender and ethnicity. Our results did not find that body weight is associated with PPGR in healthy adults, and the wholemeal bread used in the current study did not deliver the health benefit of attenuating PPGR compared with white bread consumption despite the higher dietary fibre content.