Portion Size: What We Know and What We Need to Know

There is increasing evidence that the portion sizes of many foods have increased and in a laboratory at least this increases the amount eaten. The conclusions are, however, limited by the complexity of the phenomenon. There is a need to consider meals freely chosen over a prolonged period when a range of foods of different energy densities are available. A range of factors will influence the size of the portion size chosen: amongst others packaging, labeling, advertising, and the unit size rather than portion size of the food item. The way portion size interacts with the multitude of factors that determine food intake needs to be established. In particular, the role of portion size on energy intake should be examined as many confounding variables exist and we must be clear that it is portion size that is the major problem. If the approach is to make a practical contribution, then methods of changing portion sizes will need to be developed. This may prove to be a problem in a free market, as it is to be expected that customers will resist the introduction of smaller portion sizes, given that value for money is an important motivator

Efficiency of five biosolids to supply nitrogen and phosphorus to ryegrass Eficiência de cinco biossólidos em suprir nitrogênio e fósforo para azevém

Biosolids have been considered satisfactory to supply crops and plant nutrients. The ideal biosolids application rate should result in high crop yields and nutrient uptake, and leave low concentrations of nutrients in soils to avoid environmental problems. The objective of this study was to estimate the capacity of five biosolids to supply N and P to ryegrass (Lolium perenne) after a single application of either fertilizers or biosolids to a Spodosol and an Oxisol. Results showed that 6% - 36% of N and 3% - 7% of P applied as biosolids were recovered in plants grown on the Spodosol, while the range on the Oxisol was 26%-75% for N and 1.2%-3.7% for phosphorus. Biosolids' efficiency on supplying N and P to plants was similar to fertilizer on the Spodosol, but on the Oxisol it refrained to 65%-67% fertilizer's efficiency. After a single application of biosolids followed by six consecutive harvests, 25%-94% of the N and 93%-99% of the P were not used by plants and remain in the soils.<br>Biossólidos têm sido considerados eficientes em suprir nutrientes às culturas. A dose ideal deve resultar em alta produtividade e absorção de nutrientes pelas plantas e em baixas concentrações de elementos químicos nos solos, a fim de se evitar problemas ambientais. O objetivo deste trabalho foi estimar a capacidade de cinco biossólidos em suprir N e P para o azevém (Lolium perenne) após a aplicação de dose única de fertilizantes ou de biossólidos num Espodossolo e num Latossolo. Os resultados mostram que entre 6%-36% do N e 3%-7% do P aplicado como biossólidos foram recuperados nas plantas cultivadas no Espodossolo, ao passo que no Latossolo os valores variaram de 26%-75% quanto ao N e 1,2%-3,7% quanto ao fósforo. A eficiência de biossólidos em suprir N e P para as plantas foi similar ao fertilizante no Espodossolo, mas no Latossolo alcançou o limite de 65%-67%, medida com a aplicação de fertilizantes. Após uma única aplicação de biossólidos seguida de seis colheitas consecutivas, 25%-94% do N e 93%-99% do P adicionados não são utilizados pelas plantas e permanecem nos solos