The Far Reaches of Hypothetical Dietary Design
Based on recent research, it seems to be the case that the operation of calorie restriction in laboratory-bred flies is as dependent on what a fly senses as what it eats. See this review for example:
Could the mere perception of food availability reverse the beneficial effects of diet restriction, which robustly increases lifespan and reduces aging-related disease in many species? We had noted from previous work in Drosophila that the effects of dietary restriction were fast acting, completely reversible, and largely independent of the energetic content of the food. Indeed, some characteristic of the diet seemed to be "sensed" by the flies independent of their tendency to eat it. We quickly realized that the Drosophila olfactory system, with its well-understood architecture and associated set of genetic tools, was the ideal model to test our hypothesis. Subsequent work resulted in the identification of particular odorants and populations of sensory neurons with potent effects on lifespan, obesity, and metabolism.
From there one would hypothesize that a diet for flies could be constructed that doesn't use methionine or protein restriction to trigger calorie restriction benefits, yet nonetheless extends life span and enhances health through use or avoidance of specific scents.
Then we might ponder, completely speculatively, whether primates have inherited any such sensitivity to specific scents as part of our evolutionary heritage. There is no evidence to suggest that we have, but it is nonetheless interesting to postulate a scent-based array of possible ways to build a diet that is rich in calories but still triggers some form of positive calorie restriction biochemistry.
Meanwhile, feet back on the ground, the strong evidence for the benefits of methionine restriction in mammals is a fairly direct pointer to a way to engineer a diet that will produce health benefits without adopting a calorie restriction lifestyle. I continue to be surprised that no elements within the "anti-aging" marketplace are pursuing this sort of product development; given the financial success and public awareness of branded dietary products, you'd think this would be right up their alley.
Pletcher, S. (2009). The Modulation of Lifespan by Perceptual Systems Annals of the New York Academy of Sciences, 1170 (1), 693-697 DOI: 10.1111/j.1749-6632.2009.04926.x