There are EXTENSIVE studies that show a restricted calorie diet can lead to extremely long life. That means that a normal diet leads to comparatively shorter lifespan. It may have something to do with mitochondrial degredation by the extra processing it does due to a high caloric intake. Look up the I'm Not Dead Yet gene in drosophila, and its homolog in mice. The idea is that eating more of ANYTHING is probably going to cause more rapid degredation of your mitochondria, and therefore probably shorten your lifespan, but which is worse? Is it worse to die at 75 rather than 80 after a lift of health, fitness, and pulling tons of girls with your 8-pack and V and rippling biceps? Or is it better to live out those 5 years as an invalid in an old folks home.
You shouldn't do things to avoid dying, sicne that could happen at any time and it's guaranteed to happen eventually. You should act to improve the quality of your life. That is why I eat as much as I can at every meal, and take a protein supplement daily. I enjoy the food and it improves the quality of my life by helping me gain muscle.