Over the past many years or decades, people believed that obesity was caused by a misbalance of calories: obese patients consume more calories that they expend. While this is true in many cases, it is not the complete picture. Recent research is discovering a whole host of causes that contribute to obesity and it is not just calories. Ignoring the evolving genesis of obesity is doing a terrible disservice to patients.

Obesity is now an epidemic in the US as well as many other countries around the globe. Alarmingly, the rate also appears to be increasing annually. According to the American Heart association, there are 154.7 million people who meet the criteria for being overweight or obese among adults over the age of 20 years in the US. In 2013, a Gallup poll found a statistically significant increase in the rate of obesity from 26.2% to 27.2% of American adults. This increase was observed across all major demographic and socioeconomic groups.

Even more alarming is the rapid gain in the number of children and adolescents with obesity. Over the past three decades, the CDC tells us that the number of children with obesity has doubled and the number of adolescents has quadrupled. Among children 6-11 years old, 18% meet the criteria for obesity. In those aged 12-19, nearly 21% now are considered obese.

Obesity gives rise to many other conditions, including diabetes mellitus, hypertension, osteoarthritis and many others. Additionally, many studies are now showing the factors that contribute to obesity now play a role in the development of many cancers. It is therefore imperative that we achieve a full understanding into what causes obesity.

What is the genesis of obesity?


We are all aware of this cause: if calories out do not exceed calories in, weight gain is the results. However, this is an overly simplified view of this cause. It does not take into account the type of calories that are taken in or how it is expended. Science tells us that different food types are digested and broken down differently. Therefore, it is important to know if a calorie came from a protein or a carbohydrate, etc.  Also, not all exercise burns calories at a similar rate. To truly evaluate this cause we need all this additional information. In the 21st century, the calories in/calories out model no longer is valid in and of itself.

In the US, culture teaches us to eat poorly. We live in a fast-paced instant gratification society. This applies to our food choices and how we eat as well. It is much easier to go through a drive-thru at a fast food restaurant than to search out a healthy meal when we are on a tight schedule. And most of these foods are laden with saturated fats and heavy with “bad” calories. These foods are made to be very tasty and are heavily marketed to children.

As a society, we are exercising less. In our schools, budget cuts often come at the cost of sports teams. People cite lack of time as reason not to exercise and this may be true for many. But, we are living in a more technological and digitalized society. It is hard to get people unplugged from their mobile and not so mobile devices for long enough to do most anything.  Many parents complain that they can’t get their kids to stop playing computer games. Even our interactions with other people are becoming more virtual and less real world. We can talk to people all across the globe without getting out of our seats.

  1. GENES

Genetic factors are increasingly being found to play a significant role in the development of obesity. Obesity is often found to run in families and it is not environmental causes alone that contribute.  Research is showing more and more genetic influence. Obesity,, in fact, appears to be influenced  by  polygenetic  conditions. The Human Obesity Gene Map shows the complexity of genes and obesity. Not only do genes predispose certain individuals to obesity, they also appear to predispose some to the diseases caused by obesity.


There is currently much research being conducted in this area. In fact, many pharmaceutical companies are exploring this association to develop new medications that may treat obesity. There are a whole host of neuroendocrine factors that appear to make some contribution to obesity. These factors especially appear to play a role in visceral obesity and may explain why it is more common in patients with certain diseases such as diabetes mellitus and Cushing’s disease.

Some interesting studies have been carried out in primates and show that a stress reaction is often followed by visceral fat accumulation, similar to humans. Neuroendocrine factors appear to be a major influencer here.


Many new interesting studies have come out linking lack of sleep with obesity. The largest study and longest study currently done on adults on this topic is the Nurses’ Health Study. It looked at 68,000 middle-age American women for up to 16 years. Compared to women who slept seven hours a night, women who slept five hours or less were 15 percent more likely to become obese. There have been many studies done on 5 continents in children showing a similar correlation between decreased amounts of sleep and decreased weight.


Other possible contributors to obesity are certain disease, medications and emotional factors.

Obesity has hit epidemic proportions among children and adults across the world. Without a full understanding as to why it develops, we will never be able to treat it effectively. If the rates continue to rise as rapidly as they have been, we will see epidemic rises in the rates of diseases where obesity is implicated, such as diabetes, many types of cancer, etc. We need to identify these causes and aim treatment at treating these underlying causes of obesity. Yes, energy balance does play a significant impact and eating healthy and exercising is always a good goal. But, if we do not address the whole story, we will continue to fail and we will see a reversal of our life expectancy that is unprecedented in history.


About the Author

Linda Girgis MD, FAAFP is a family physician practicing in South River, New Jersey. She was voted one of the top 5 healthcare bloggers in 2016. Follow her on twitter @DrLindaMD.