The aroma of calories

Food sniffing cancels the lifespan extension that comes from caloric restriction

Roital Lavie, Galileo 

As early as 70 years ago, evidence began to accumulate that limiting calorie intake, while consuming nutrients in sufficient quantity, could prolong life. Since then, a group called the Caloric Restriction Society of North Carolina has grown to 1,800 members who have reduced their caloric intake to half that recommended by the US Food and Drug Administration (FDA), hoping to live to be 120 years old. A new study will recommend that the organization attach nasal plugs to its next leaflet...
A group of scientists from the Baylor School of Medicine and the University of Houston in New Mexico found that the average lifespan of fruit flies fed a limited amount of calories decreased when they were exposed to food odors. The head of the group, Scott Fletcher (Pletcher) from Baylor's Huffington Center for the Study of Aging, claims that the flies sense the environment and believe that they are in a place rich in nutrients, and their bodies react accordingly.
The researchers conducted an experiment in which flies of two strains participated. The researchers exposed flies of both strains, which were fed a limited amount of calories, to the odors of yeast, an important component of the flies' menu. These flies died 3-10 days before their brothers who were not exposed to the yeast odors - a 6-18 percent decrease in lifetime! The lifespan of the flies was shortened as if they had actually eaten the yeast they smelled.
Fletcher claims that the smell of yeast only affects flies that are fed a low-calorie diet, and has no effect on flies that are fed a normal menu, which anyway perceive their immediate environment as an environment rich in nutrients. That is, animals that are fed a low-calorie diet, and are in a different physiological state, which grants a long life, are affected by food odors, which to a certain extent eliminate this physiological state. There is, therefore, some interaction between smell and physiological state.
To test these conclusions, Fletcher's team created a strain of flies whose olfactory receptors were defective. In odorless females that were fed a rich diet, a lifespan extension of 56 percent was found compared to the wild strain. Males lacking a sense of smell also lived longer than their wild-type counterparts. Fletcher believes that these findings indicate that smell-dependent aging and the effects of the menu on aging probably share similar physiological mechanisms.
It is possible that flies without a sense of smell eat less; It is possible that life span is controlled not only by real resources (food) but also by hormones, the secretion of which is influenced by smell. Before us, therefore, is a complete system that is not only affected by the actual resources, but also by information about the amount of resources in the force.