According to a study quoted in the Daily Mail, men who are obese by the time they are 20 double their risk of dying prematurely.
The study also found that a majority of obese 20-year olds found it increasingly harder to lose weight as their got older.
The new research was presented at the International Congress on Obesity in Stockholm.
Scientists followed more than 5,000 army conscripts starting at age 20 until they were 80. They learned that obese men at any age are two times more likely to die a premature death.
The study showed how obese men died on average eight years earlier than men who had a normal weight.
Study leader, Esther Zimmermann works at the Copenhagen University Hospital. She commented: "As the obesity epidemic is still progressing rapidly, especially among children and adolescents, it is important to find out if obesity in early adulthood has lifelong mortality effects."