While the typical body starts to deteriorate after 3 weeks without food, some people are able to slow their metabolism and survive significantly longer, potentially up to 60 days. According to Dr. Mike Stroud, an international authority in human endurance, it is extremely rare but possible for a human to survive around 60 days without food, granted the weather conditions are right and the person has access to water.
In 1981, Bobby Sands dies after 66 days of a hunger strike. Other stories have emerged of stranded hikers surviving upwards of 50 to 60 days. Without food, the body succumbs to hunger and starts to eat away at muscle tissue and fat for energy. Some bodies are able to do this more efficiently than others, which explains the huge gap in how long a person can survive without eating.