Obesity reduces longevity by 8 years

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Doctors at the Research Institute of the McGill University Health Centre and McGill University examined the relationship between body weight and life expectancy. Their findings show that overweight and obese individuals have the potential to decrease life expectancy by up to 8 years. The study, published in the The Lancet Diabetes and Endocrinology, further demonstrates that when one considers that these individuals may also develop diabetes or cardiovascular disease earlier in life, this excess weight can rob them of nearly two decades of healthy life.

“In collaboration with researchers from the University of Calgary and the University of British Columbia our team has developed a computer model to help doctors and their patients better understand how excess body weight contributes to reduced life expectancy and premature development of heart disease and diabetes,” says lead author Dr. Steven Grover. Diabetes and cardiovascular disease: the predictors of health Dr. Grover and his colleagues used data from the National Health and Nutrition Examination Survey (from years 2003 to 2010) to develop a model that estimates the annual risk of diabetes and cardiovascular disease in adults with different body weights. This data from almost 4,000 individuals was also used to analyze the contribution of excess body weight to years of life lost and healthy years of life lost.

Their findings estimated that individuals who were very obese could lose up to 8 years of life, obese individuals could lose up to 6 years, and those who were overweight could lose up to three years.

In addition, healthy life-years lost were two to four times higher for overweight and obese individuals compared to those who had a healthy weight, defined as 18.5-25 body mass index (BMI). The age at which the excess weight accumulated was an important factor and the worst outcomes were in those who gained their weight at earlier ages. “The pattern is clear – the more an individual weighs and the younger their age, the greater the effect on their health,” Dr. Grover adds. “In terms of life-expectancy, we feel being overweight is as bad as cigarette smoking.”

Hidden Sugars and Obesity

While some doctors say fructose is being unfairly maligned-1, other researchers say consumption of calorie-sweetened beverages has continued to increase and plays a role in the epidemic of obesity, the metabolic syndrome, and fatty liver disease. Reducing intake of soft drinks is associated with less weight gain.2 Recently, researchers at the University of Colorado School of Medicine reported that the cause of obesity and insulin resistance may be tied to the fructose your body makes in addition to the fructose you eat.

Studies challenge fructose

In recent years the role of added sweeteners, such as high fructose corn syrup and table sugar (sucrose), has taken center stage as risk factors for obesity and insulin resistance. Numerous studies suggest that the risk from added sugars may be due to the fructose content. In a study published in Nature Communications,  University of Colorado School of Medicine researchers reported that fatty liver and insulin resistance may also result from fructose produced in the liver from non-fructose containing carbohydrates. The study, whose first authors are Miguel Lanaspa, PhD, and Takuji Ishimoto, MD, reported that mice can convert glucose to fructose in the liver, and that this conversion was critical for driving the development of obesity and insulin resistance in mice fed glucose. “Our data suggests that it is the fructose generated from glucose that is largely responsible for how carbohydrates cause fatty liver and insulin resistance,” said Lanaspa. Richard Johnson, MD, professor of medicine and chief of the division of renal diseases and hypertension at the School of Medicine and senior author of the paper, said: “Our studies provide an understanding for why high glycemic foods may increase the risk for obesity and insulin resistance. While some of the weight gain is driven by the caloric content and the effects of stimulating insulin, the ability of high glycemic foods to cause insulin resistance and fatty liver is due in part to the conversion of glucose to fructose inside the body.

“Ironically, our study shows that much of the risk from ingesting high glycemic foods is actually due to the generation of fructose, which is a low glycemic sugar. These studies challenge the dogma that fructose is safe and that it is simply the high glycemic carbohydrates that need to be restricted.”3

Associations between fructose consumption and weight gain

In a study examining possible factors regarding the associations between fructose consumption and weight gain, brain magnetic resonance imaging of study participants indicated that glucose but not fructose reduced cerebral blood flow and activity in brain regions that regulate appetite, and ingestion of glucose but not fructose produced increased ratings of satiety and fullness.4

In other words – fructose can trigger brain changes that may lead to overeating. This research while new, reveals findings consistently found over the past few years. In another study, overweight and obese individuals who consumed glucose- or fructose-sweetened beverages that provided 25% of their energy requirements for 10 weeks were observed. During this period, individuals in both groups put on about the same amount of weight, but only those consuming fructose-sweetened beverages exhibited an increase in intraabdominal fat. Further, only these individuals became less sensitive to the hormone insulin (which controls glucose levels in the blood) and showed signs of dyslipidemia (increased levels of fat-soluble molecules known as lipids in the blood).

In a recent article we noted research that also suggested how a diet steadily high in fructose slows the brain, hampering memory and learning.

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1. van Buul VJ, Tappy L, Brouns FJ. Misconceptions about fructose-containing sugars and their role in the obesity epidemic. Nutr Res Rev. 2014 Mar 25:1-12. [Epub ahead of print] 1. http://www.eurekalert.org/pub_releases/2013-09/uocd-rlo091013.php

2. Journal of Clinical Investigation News Release

3. JAMA News Release

4 Bray GA, Popkin BM. Dietary sugar and body weight: have we reached a crisis in the epidemic of obesity and diabetes?: health be damned! Pour on the sugar. Diabetes Care. 2014 Apr;37(4):950-6. doi: 10.2337/dc13-2085.