Obesity linked to premature death

It is well known that being overweight can lead to health complications including diabetes, heart disease, stroke and cancer.

A recent study published in Lancet reports on a meta-analysis of 239 prospective studies published from 1970 to last year (median follow-up 13·7 years).  Of those 3 951 455 people in 189 studies were never-smokers without chronic diseases at recruitment who survived 5 years, of whom 385 879 died.   The investigators extracted their information from 10 625 411 participants in Asia, Australia and New Zealand, Europe, and North America.

They compared the risk of death to people's body mass index, or BMI, a measure of body fat that is calculated using height and weight.  They defined a BMI from 18.5 to 25 as normal, 25-30 as overweight, 30-35 as moderately obese and over 40 as severely obese.

In the study, the risk of dying before the age of 70 was 19 percent for men and 11 percent for women of normal weight.

But that risk jumped to 30 percent and 15 percent, respectively, for obese men and women.  The investigators found that overweight people die one year earlier than expected and that moderately obese people die up to three years prematurely.

The World Health Organization estimates that 1.3 billion adults worldwide are overweight, and 600 million more are obese. The associations of both overweight and obesity with higher all-cause mortality were broadly consistent in all four continents. As common diseases such as heart disease, stroke, diabetes and cancer have been strongly associated to obesity, strategies to combat it are needed all around the globe.

Obesity in the United States

Two reports published in the Journal of the American Medical Association by Flegal et al and Ogden et al find that 35% of men and 40% of women and 17% of children and teens were obese as of 2014. The corresponding values for class 3-obesity (morbid) were 5.5% for men, 9.9% for women and 6% for children and teens.

The authors obtained their data from the National Health and Nutrition Examination Survey (NHANES), a cross-sectional, nationally representative health examination survey of the US population that includes measured weight and height.

Obesity in adults was defined when the BMI (body mass index) was ≥30 and class 3 obesity when the BMI was ≥40.

This report is based on data from 2638 adult men (mean age, 46.8 years) and 2817 women (mean age, 48.4 years) from the most recent 2 years (2013-2014) of NHANES and data from 21 013 participants in previous NHANES surveys from 2005 through 2012.

Measurements from 40 780 children and adolescents (mean age, 11.0 years; 48.8% female) between 1988-1994 and 2013-2014 were also analyzed.

Obesity in children was defined as a body mass index (BMI) at or above the sex-specific 95th percentile on the US Centers for Disease Control and Prevention (CDC) BMI-for-age growth charts. Extreme obesity was defined as a BMI at or above 120% of the sex-specific 95th percentile on the CDC BMI-for-age growth charts. Detailed estimates were presented for 2011-2014. Trend analyses between 2005-2006 and 2013-2014 also were conducted.

For women, the prevalence of overall obesity and of class 3 obesity showed significant linear trends for increase between 2005 and 2014; there were no significant trends for men.

The odds of being obese fluctuated with age. The researchers found that 41% of adults in their 40s and 50s were obese, compared with 34% of adults in their 20s and 30s and 39% of adults ages 60 and older.

There were also differences based on race and ethnicity. At one end of the spectrum were Asian Americans, 13% of who were obese. At the other end were African Americans, 48% of whom were obese. In between were Latinos (43%) and whites (36%).,

The two reports suggest that the U.S. obesity epidemic continues to worsen and that efforts to encourage Americans to lose or stop putting on more weight are having little effect.

Worldwide increase in obesity

A study that was published in Lancet reports an alarming worldwide increase in the prevalence of obesity.

The authors estimated incidence and trends in mean body-mass index (BMI) categories, of males and females in 186 countries.

The researchers gathered population-based data that measured the height and weight of 19 million adults (9·9 million men and 9·3 million women) for which estimates were made.  They used statistical methods to estimate trends in global and national weight patterns from 1975 to 2014.  During this period global age-standardized mean BMI increased from 21·7 kg/m² to 24.2 kg/m² in in men, and from 22·1 kg/m² in to 24·4 kg/m² in women (normal BMI range is 18.5 to 22.1 kg/m²⁾. Regional mean BMIs in 2014 for men ranged from 25 kg/m² in central Africa and south Asia to 29.2 kg/m² in Polynesia and Micronesia; for women the range was from 21.8 kg/m² in south Asia to 32.2 kg/m² in Polynesia and Micronesia (BMI for the overweight category ranges from 25 kg/m² to 30 kg/m², for the obese from 30 kg/m² to 35 kg/m² while those individuals having a BMI over 35 are morbidly obese).  Finally 2.3% of the world's men and 5·0% of women were morbidly obese (i.e., have BMI ≥35 kg/m²).

Over the past 40 years there has been an unprecedented increase in the number of obese adults worldwide, climbing to about 640 million from 105 million in 1975.  If the post-2000 trends continue, by 2025, global obesity prevalence will reach 18% in men and surpass 21% in women; severe obesity will surpass 6% in men and 9% in women.  The study found that the number of obese people surpasses the number of people who are underweight.

Aspirin use decreases the risk of gastrointestinal cancers

Research by Cao et al published in JAMA Oncology suggests that regular aspirin use may be associated with lower risk of certain cancers.

The investigators looked at data on approximately 136,000 individuals who enrolled at two large US prospective cohort studies, the Nurses’ Health and Health Professionals studies. 

Among the 88 084 women and 47 881 men who underwent follow-up for as long as 32 years, 20 414 cancers were detected among women while 7571 cancers were found in men. Compared with nonregular use, regular aspirin use was associated with a lower risk for overall cancer, which was primarily due to a lower incidence of gastrointestinal tract cancers especially colorectal cancers. The benefit of aspirin on gastrointestinal tract cancers appeared evident with the use of at least 0.5 to 1.5 standard aspirin tablets per week; the minimum duration of regular use associated with a lower risk was 6 years. Among individuals older than 50 years, regular aspirin use could prevent 33 colorectal cancers per 100 000 person-years (PAR, 17.0%) among those who had not undergone a lower endoscopy and 18 colorectal cancers per 100 000 person-years (PAR, 8.5%) among those who had.

The researchers found that taking aspirin regularly—defined twice a week or more—for at least six years was associated with a 19% drop in risk for colon and rectum cancers, a 15% lower risk for gastrointestinal tract cancers and a 3% lower risk for cancers in general. The researchers did not find a link between regular aspirin use and risk reduction for some other cancers, including cancers of the breast, prostate and lung.

The benefits for GI cancers seemed to manifest even with a lower dose of aspirin, starting with half a standard aspirin tablet weekly. The authors found that taking aspirin regularly could prevent anywhere from 8-17% of colorectal cancers in people older than 50.

The authors concluded that long-term aspirin use was associated with a modest but significantly reduced risk for overall cancer, and may prevent a substantial proportion of colorectal cancers and thus complement the benefits of screening.

Exercise linked to reduced risk of several cancers

Physical activity has been associated with lower risk of heart disease and all cause mortality, but its association with risk of cancer is not well understood.

Moore et al research published in JAMA Internal Medicine, suggests that exercise is a powerful cancer-preventive and found that physical activity drove down the rates of a broad array of cancers even among smokers, former smokers, the overweight and obese.

Researchers collected data from 12 prospective studies from the United States and Europe and analyzed associations between self-reported physical activities with the incidence of 26 types of cancer in the study period, which lasted 11 years between 1987 and 2004.

A total of 1.44 million participants (median [range] age, 59 [19-98] years; 57% female) and 186 932 cancers were included. High versus low levels of physical activity were associated with lower risk of 13 cancers: esophageal adenocarcinoma, liver, lung, kidney, gastric, endometrial, myeloid leukemia, myeloma, colon, head and neck, rectal, bladder, and breast. The data indicated that a higher level of activity was tied to a 7 percent lower risk of developing any type of cancer. Individuals who were very active had a 20% lower risk of cancers of the esophagus, lung, kidney, stomach, endometrium compared with people who were less active.  The reduction was slightly lower for colon, bladder, and breast cancers.

Body mass index adjustment modestly attenuated associations for several cancers, but 10 of 13 inverse associations remained statistically significant after this adjustment. Leisure-time physical activity was associated with higher risks of malignant melanoma and prostate cancer.  Associations were generally similar between overweight/obese and normal-weight individuals. Smoking status modified the association for lung cancer but not other smoking-related cancers.

Health care professionals should emphasize that physical activity was associated with lower risks of many cancer types and most of these associations were evident regardless of body size or smoking history.