Diet composition and energy intake in humans.

Absolute energy from fats and carbohydrates and the proportion of carbohydrates in the food supply have increased over 50 years. Dietary energy density (ED) is primarily decreased by the water and increased by the fat content of foods. Protein, carbohydrates and fat exert different effects on satiety or energy intake (EI) in the order protein > carbohydrates > fat. When the ED of different foods is equalized the differences between fat and carbohydrates are modest. Covertly increasing dietary ED with fat, carbohydrate or mixed macronutrients elevates EI, producing weight gain and vice versa. In more naturalistic situations where learning cues are intact, there appears to be greater compensation for the different ED of foods. There is considerable individual variability in response. Macronutrient-specific negative feedback models of EI regulation have limited capacity to explain how availability of cheap, highly palatable, readily assimilated, energy-dense foods lead to obesity in modern environments. Neuropsychological constructs including food reward (liking, wanting and learning), reactive and reflective decision making, in the context of asymmetric energy balance regulation, give more comprehensive explanations of how environmental superabundance of foods containing mixtures of readily assimilated fats and carbohydrates and caloric beverages elevate EI through combined hedonic, affective, cognitive and physiological mechanisms. This article is part of a discussion meeting issue 'Causes of obesity: theories, conjectures and evidence (Part II)'.

Towards a satiety map of common foods: Associations between perceived satiety value of 100 foods and their objective and subjective attributes.

Hunger is one of the main reasons given by people experiencing problems in managing their weight. Identifying the types and properties of foods that enhance satiety may help consumers improve appetite control and weight management. However the attributes of foods associated with their perceived satiety value have been largely unexamined. The current research examined a range of objective and subjective attributes of foods and sought to map them onto ratings of their perceived satiety value. Participants (n=1127) rated 100 individual food images, through online surveys, based on subjective (e.g. perceived energy content, control over eating, healthiness, palatability) and objective (e.g. actual energy content, macronutrient composition, cost/kcal) attributes. Perceived satiety value was quantified from ratings of how filling each food was judged to be. Results showed that when controlling for perceived total energy content, perceived satiety value was associated with lower energy density (r=-.74), lower %fat (r=-.47), higher %protein (r=.31) and higher cost (r=.48). In terms of subjective attributes, perceived satiety value was associated with greater healthiness (r=.90), weight management (r=.91), frequency of consumption (r=.58) and greater control over eating (r=.76). Linear regression models indicated that the objective attributes of energy density, %fat, fibre content, %carbohydrate and cost (R(2)=.69) and the subjective attribute of utility for weight management and frequency of consumption (R(2)=.83) accounted for the most variance in the perceived satiety value of food. These findings may help towards a 'satiety map' of the diet with implications for public health promotion and the development of satiety enhancing foods.

Effects of added fruits and vegetables on dietary intakes and body weight in Scottish adults.

An increased consumption of fruits and vegetables (F&V) has been suggested as a way to limit, or even lower, energy and fat intakes. The present study examined the effects of incorporating F&V supplements into the diets of adults who reported consuming <240 g (three portions) of F&V per d on energy and fat intakes, and change in body weight, over 8 weeks using a randomised parallel design. Thirty-four males and twenty-eight females (age 42.6 (sd 11.1) years, BMI 23.7 (sd 2.7) kg/m(2)) were each provided with supplements of 0, 300 or 600 g F&V per d. Food, nutrient and energy intakes were measured before, during and at the end of the supplementation period using 7 d weighed records. Mean daily energy intakes were not different among the three groups before (P = 0.151) or during the supplementation periods (P = 0.407), although changes in energy intakes over the study period tended to be more positive with increasing amounts of F&V supplements (P = 0.078). There was no difference in changes of body weights during the study (P = 0.242). Carbohydrate (P < 0.001), sugar (P < 0.001), fibre (P < 0.001) and weight of food consumed (P = 0.022) increased in the treatment groups. There were no significant differences, or changes, in fat intakes among the three groups. Consumption of mandatory F&V supplements for 8 weeks produced beneficial changes in diet composition, but did not result in lower reported energy or fat intakes, and did not result in loss of body weight.