Without taking into account the known complications, the effects of obesity and excess weight alone have long been disputed in the medical community.
Previous studies have found that being obese and overweight are risk factors for stroke, heart disease, type 2 diabetes and cancer, which can all lead to an early death. However, there is no general consensus on the absolute impact of both medical conditions.
Being obese or overweight can be determined by measuring a person's body mass index (BMI), although many scientists argue that this is a "flawed measure." BMI charts weight against height, but experts say it does not allow for the muscle that replaces fat, particularly in athletes.
Now, a new study conducted by a large group of international experts sought to find a definitive answer to this longstanding dispute.
A Meta-Analysis Of All Studies
Researchers analyzed a vast amount of data gathered in separate small-scale studies which involved 3.9 million adults in 32 countries across the world.
They compared the mortality risk to the participants' BMI, and they defined the following: 18.5 to 25 as normal BMI; 25 to 30 as overweight; 30 to 35 as moderately obese; and more than 40 as severely obese. For instance, someone who is 5 feet 4 inches tall is obese even at a weight of 174 pounds (78 kilograms) or more.
In the end, scientists found that overweight people faced premature death compared to those who were of normal weight.
Overweight people lose one year of life on average compared to their peers, while those who were moderately overweight lose about 3 years of their life, researchers say.
A previous study also discovered that severe obesity could lead to the loss of as much as 8 years in life expectancy.
Differences Between Men And Women
Additionally, researchers discovered a huge gap between obese men and obese women, revealing that obesity is much more dangerous in the former than the latter.
Richard Peto, one of the authors of the study and an expert from Oxford University, says the risk of premature death is nearly thrice as big for men who are obese compared to women who are obese.
He says that men were at higher risk of premature death in general and the mortality risk worsens when obesity is added to the equation.
Statistics from the Global BMI Mortality Collaboration showed that men with normal BMI had a 19 percent risk of premature death, while women with normal BMI faced an 11 percent chance.
For men who are moderately obese, the mortality risk rises to 29.5 percent. For women with the same BMI, the risk is 14.6 percent.
Reduce Obesity Rates
Researchers say that if obesity does directly cause the premature deaths, one out of seven cases could be avoided in Europe, while one out of five could be avoided in North America if those who are obese could reach normal weight.
Peto acknowledged that more is needed than simply telling people to lose weight, because reducing a few pounds and maintaining it is difficult.
"It might be easier to recommend that people try very hard not to put on weight in the first place, particularly before they hit middle age," says Peto.
Details of the study are featured in the journal The Lancet.
Photo: Tony Alter | Flickr