Even when they know what they are eating is high-calorie, most people do not change their eating habits. Pleunie Hogenkamp of the Human Nutrition chair group reached this surprising conclusion after getting students to eat high-calorie and low-calorie yoghurt for 20 days. The foods were clearly distinguishable by taste. The test subjects proved slow learners. Contrary to expectations, they did not eat less of the high-calorie yoghurt. Nor did it make a difference whether it was thick or thin yoghurt.
Knowledge but no action
A second experiment made clear that the test subjects did adjust their behaviour somewhat when different foods were combined. Students who first ate a low-calorie pudding took larger helpings of the next dish than those who ate a more substantial pudding first. But this adaptation hardly compensated for the difference: the ‘high-calorie group’ still ate over 500 calories more. So eating habits seems to be hard to influence. ‘It seems we do learn’, says Hogenkamp, ‘but we do not act on the new information.’ The PhD researcher defends her thesis on 13 January.