Food characteristics and dietary intake : the role taste, eating rate and energy density

The increases in obesity prevalence coincide with changes in our food environment, such as an increased consumption of processed, energy dense foods. This suggests that the foods we consume are at least partly responsible for the obesity epidemic. The aim of this thesis is therefore to investigate food characteristics, with the focus on taste, eating rate and energy density, and their relation to dietary intake. Taste is studied in two respects. First, the contribution of taste qualities to the diet is investigated, using the Food Consumption Survey 2003. Foods are classified according to their predominant taste (sweet, salty or savoury, sour, bitter or neutral). Energy intake of the foods within taste categories is assessed, showing that the largest part (34%) of the daily energy intake originates from sweet foods. Second, it is investigated whether taste, which is supposed to be a nutrient sensor, can fulfil this function within the current diet. Intensities of the five basic tastes of 50 commonly consumed foods are therefore assessed and associated with the nutrient content. Positive associations are found between sweetness and mono- & disaccharides and between both saltiness and savouriness and sodium and protein. The associations are less pronounced in highly processed foods, which suggests that in these foods the ability to sense nutrient content based on taste is limited. The influences of an incongruence between sensory properties and nutrient content are also investigated, byexamining the effects of fat perceptionon energy intake. We demonstrated that energy intake is almost 10% lower in case of visible fats compared to hidden fats, suggesting that hidden fats may contribute to overconsumption. Eating rateseems to be associated with food intake. The contribution of eating rate to the diet is investigated, using the Food Consumption Survey 2003. Foods are classified into one of four eating rate categories, and energy intake of the foods within each category is assessed. Results demonstrate that foods with slow calories (kJ/min) provide 10%, whereas foods with fast calories provide 37% to the daily energy intake. So in the current diet, the consumption of foods with a high eating rate is high. The effects of eating rate on intake are also investigated, showing that eatingrate is positively associated with food and energy intake. People may therefore be at risk of overconsumption, when consuming foods with a high eating rate. Consuming energy dense snacks is often blamed for affecting energy balance, but findings are inconclusive. Therefore, effects of snack consumption on body weight are investigated. No changes in body weight are observed after 8 weeks, when energy density of snacks was either low or high. This suggests that consuming snacks does not necessarily contribute to weight gain, at least in normal-weight young adults. In conclusion,when taste and other sensory properties do not accurately reflect the nutrient content, which applies particularly to highly processed foods, this may lead to high food intakes. In addition, a large part of the daily energy intake originates from foods with a high eating rate, which stimulates food and energy intake. So the high eating rate of the foods in the current diet may be responsible for overconsumption. These findings may be helpful in following the recommendations of the Nutrition Centre to lose weight. Last, even though we did not find evidence that consuming energy dense snacks results in weight gain, the advice should nevertheless be to limit the intake of energy dense foods, at least until evidence becomes more conclusive.