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... or even less

Some people are willing to go even farther on their quest for eternal youth: Studies have shown that animals live longer if they eat only every other day, and a few diet programs have embraced this idea. (These types of diets are likely very difficult to follow, however, and not safe for people with any chronic health conditions.) Research from Washington University has also found that people who restrict their calorie intake have lower core temperatures—an indication that their bodies can operate as efficiently as possible.

Next: Japanese diet