In an ad titled "Pep talk with Stephen Hawking" the cosmologist and physicist addresses "the most serious public health problems of the 21st century."
"Today too many people die from complications related to overweight and obesity. We eat too much and move too little," Professor Hawking says in the ad shot for Swedish non-profit GEN-PEP.
The solution, he says, "is not rocket science," and he recommends that people eat less and take up more physical activity.
The British cosmologist, considered by many the smartest man alive, concludes "For what it's worth, how being sedentary has been a major health problem is beyond my understanding."
GEN-PEP is a non-profit launched by The Swedish Crown Princess Couple to help “spread knowledge and get people involved in promoting the health of children and young people.”
Physical inactivity is now the fourth leading cause of death in the world and most of the world's population live in countries where obesity kills more people than underweight, according to the World Health Organisation .
In 2010, US First Lady Michelle Obama launched an ambitious campaign "dedicated to solving the problem of obesity within a generation".