We're losing the war on obesity, badly. 

New research suggests childhood fitness is in decline. Researchers at the University of South Australia's School of Health Sciences found that today's children have a cardiovascular fitness that's 15 percent lower than their parents did at the same age.

The analysis of studies on 250 million children found when it comes to running a mile, 90 seconds can be added to today's kids compared to children 30 years ago.

Researchers found that cardiovascular fitness in children is in a global slump.

They also say the decline in running fitness may lead to worse health, such as heart disease, when they become adults.

The main reason is an increase in body fat.