New research carried out by University College London (UCL) scientists has found that it is possible to increase life expectancy by 50% without decreasing calorie intake - at least in fruitflies.
The research adds new complexity to the established view that dietary restriction works to extend life span by reducing calorie intake. This report reveals that the nutritional source (ie fat, protein, carbohydrate) of the calories is more important to longevity than a reduction in the total calories consumed.
The study published on 30th May 2005 in PLoS Biology, shows that fruitflies - ‘Drosophila’- can live longer without reducing calories but instead by consuming proportionally less yeast (which is the flies’ only source of protein and fat). The team, led by Professor Linda Partridge of UCL’s Centre for Research on Ageing, Department of Biology, believes that this demonstrates that calorie intake is not the key factor in the reduction of mortality rate by dietary restriction in this species.
The authors restricted the diet of the fruitflies by diluting the nutrients in the fly’s standard lab diet of yeast and sugar to a level known to maximize life span. Since both yeast and sugar (carbohydrates) provide the same calories per gram, the authors could adjust nutrient composition of the yeast/sugar mixture without affecting the calorie count, allowing them to separate the effects of calories and nutrients.