We can’t pick up the paper, go online or turn on the TV without hearing about obesity. Our society is obsessed with it. There is no end to the number of programs willing to take your money with promises of melting fat away without doing anything. So much so that in the United States alone the weight loss industry is worth more than $66 billion per year. For most of these programs, however, the only weight you’ll lose is in your wallet.

Obesity is identified using the body mass index (BMI), which is calculated by taking one’s weight (in kilograms) and dividing it by one’s height squared (in metres). A value of greater than or equal to 30 kg/m² is defined as obese, while a value of 25 to 30 is overweight. An ideal BMI is between 18.5 and 25.

Obesity is not a new phenomenon. It’s been around for thousands of years. What is new is the alarming rate at which it has increased in recent decades. It’s been increasing throughout the world for the past 50 years. In the US, now 1 in 3 adults are obese. Obesity is also increasing in countries that have historically been associated with being thin. While the prevalence of obesity in China is much lower at around 5%, it is increasing more rapidly having almost doubled in less than a decade.

Unfortunately obesity is not just limited to adults. The prevalence of obesity in US children and adolescents is 17%. While this is much higher than in years past, the prevalence does appear to be levelling off. The problem though, is that children who are obese are more likely to stay obese into adulthood and it increases the risk for diabetes in children by fourfold.

With the BMI measure used to define obesity, which uses weight in the calculation, it is common for people to mistake obesity as a condition of excess weight but it’s not. It is excess fat, not excess weight, which is the concern. Weight includes not only body fat but also muscle and bone. There are plenty of people with a BMI over 30 who are not obese and healthy. Dwayne Johnson is just one person who comes to mind. In addition, strict weight loss regimens can result in a loss of muscle. This may look good on the scale but losing muscle isn’t a sign of good health.

Excess fat is associated with a whole host of health problems. Many of these might be familiar to us such as heart disease and diabetes, but obesity is also associated with some cancers, arthritis, back problems, sleep apnea and mental health issues. People who are obese are also less likely to get married, family and get paid less than their thinner counterparts. Women who are obese or gain excess fat during pregnancy are more likely to have larger babies, which can lead to later obesity as the child grows and continue a cycle across generations. The risk for congenital defects also increases for babies of obese women.

Despite obesity increasing and individuals experiencing increasing body fat over the years, our bodies do a really good job in regulating our body fat. For many of us, from Jan 1^st to Dec 31^st of that same year, our weight may have only changed a pound or so (or for some, not at all). To me, this is incredible. When you think an average adult can eat 1996 pounds (907 kg) of food per year and has varying levels of activity during that time, the fact that our body stays so closely regulated in terms of body fat is amazing. And for most of us, we don’t eat the same amount each day. I don’t think we give enough credit to how well our body works. Of course, if we gain as little as one pound per year, over 30 years, well, that’s 30 more pounds, and most likely all fat.

What may matter more from a health perspective is where the excess fat is located. The so-called apple versus pear shape. Fat around the waist is far more problematic than fat elsewhere on our body. That’s because the fat in this area is different. It releases different amounts of certain hormones and has a different metabolism. Even a low body weight won’t protect you if you have fat around the waist.

The rapid rise in obesity is similar to that of infectious epidemics like the plague but there is no infectious agent causing obesity. Likewise, the short time frame of the increase rules out genetic origins (although genetics does have a role). Could it be a conscious decision by millions of people to eat more and exercise less? Unlikely. This would assume that obesity is fully in control of the individual. While many people believe that obesity is an individual choice, it isn’t that simple.

Many people would have you believe that if someone is obese, it’s their own fault. They ate too much or didn’t get enough exercise, or both. A national US survey supports this, in which most people laid the blame of obesity at individual choices. While we can’t ignore individual responsibility, we must look beyond that to explain the rapid rise and currently high prevalence of obesity. Shaming and blaming people who are obese is not the answer.

At the same time that obesity was increasing, our environment and way we live our lives was also changing. We’ve automated many physical tasks reducing our activity, the food we eat has changed as well as how it is made and our communities are designed in a way to prioritize the car over active transport to name a few. The Foresight Map of Obesity (above) highlights these and many other probable determinants of obesity.

In order to tackle the epidemic of obesity and potentially reverse it, we need to look for solutions that address the probable causes. We all make choices based on the options presented to us. For example, if we live in an area with a lot of fast food restaurants, we’re likely going to eat more fast food and have a greater likelihood of obesity. If, instead, we make the healthy choice the easy choice (more opportunities for healthy nutrition and physical activity), this can go a long way to impacting obesity and improving health.

In coming weeks I’ll be focusing more on obesity and related topics.

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