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 Another interesting study looking at whether being overweight is linked to premature death, heart attacks, and diabetes. This study looked at sets of twins, in which one is heavier than the other, and followed them long-term (average 12.4 years) and found that NO - being overweight or obese (as measured by Body Mass Index or BMI) is NOT associated with premature death or heart attack (myocardial infarction), but it is associated with higher rates of type 2 diabetes. These results are in contrast with what a large study recently found. From Science Daily:

Higher BMI not associated with increased risk of heart attack or early death, twin study shows

A study of 4,046 genetically identical twin pairs with different amounts of body fat shows that twin siblings with a higher Body Mass Index, as a measure of obesity, do not have an increased risk of heart attack or mortality. The study, conducted by researchers at Umeå University in Sweden, also shows that a higher BMI is associated with an increased risk of type 2 diabetes...."The results suggest that lifestyle changes that reduce levels of obesity do not have an effect on the risk of death and heart attack, which contradicts conventional understandings of obesity-related health risks," says Peter Nordström, researcher at the Department of Community Medicine and Rehabilitation at Umeå University.

In the cohort study, Peter Nordström and research colleagues at Umeå University compared health data from 4,046 monozygotic twin pairs. All twins in the study had different levels of body fat, as measured in BMI....During a follow-up period of on average 12.4 years, differences between the twins were compared when it comes to incidents of mortality, heart attack and type 2 diabetes. The results clearly showed that twin siblings with a higher BMI did not have an increased risk of mortality or heart attack compared to their thinner counterparts. However, twins with a higher BMI did have an increased risk of developing type 2 diabetes.

The results showed that: - Among twin siblings with a higher BMI (mean value 25.1), there were 203 heart attacks (5 %) and 550 deaths (13.6 %) during the follow-up period. - Among twin siblings with a lower BMI (mean value 23.9), there were 209 heart attacks (5.2 %) and 633 deaths (15.6 %) during the same period. - Among the 65 twin pairs in the study who had a BMI difference of 7 or higher, and where the larger twin siblings had a BMI of 30 or higher, there were still no noticeably increased risk of mortality or heart attack associated with a higher BMI.

The study, described in the article Risks of Myocardinal Infarction, Death, and Diabetes in Identical Twin Pairs With Different Body Mass Index, is based on the Swedish Twin Registry, the largest of its kind in the world. The median age of the twins in the study was 57.5 and participants' ages ranged from 42-92. The cohort study was conducted between 1998 and 2003, with follow-ups regarding incident of mortality, heart attack and diabetes during a 10 year period until 2013. One study limitation was that weight and length (used to calculate BMI) was self-reported.

 Another study that found benefits to dog ownership. The study authors concluded that: "Our study provides evidence that dog owners are at a lower risk for ischemic stroke, hemorrhagic stroke and heart failure." This could be to daily exercise, or that dog ownership results in less stress or better psychosocial health, or even some other reason (perhaps dog owners are healthier to start with).   Note: myocardial infarction (MI) is commonly known as a heart attack. From Medscape:

Canine Companions Appear to Help Heart Health: Swedish Study

Middle-aged and older dog owners were less likely to die from cardiovascular heart disease (CVD) or all causes, and those who lived alone were less likely to have an MI (myocardial infarction) or stroke, during a decade of follow-up in a large study based on Swedish national registry data[1]. The findings suggest that "especially for those who live alone, dog ownership makes a significant difference . . . in health status," Dr Mwenya Mubanga (Uppsala University, Sweden) told Heartwire from Medscape.....

Dog owners get daily exercise from walking their dogs, and canine companions can reduce stress, which might explain these findings, the researchers speculate....Similarly, Dr Gang Hu (Pennington Biomedical Research, Baton Rouge, LA).....pointed out that the dog owners do more exercise (by walking their dogs), which may contribute to having a lower body weight, lower blood pressure, and possibly good lipid levels and a lower risk of diabetes—which may all act to lower mortality. Having a dog may also reduce the chances of having depression, which might partly explain the more striking findings in the people who lived alone, he added.

Since 2001, dog owners in Sweden have been required by law to register their dogs, and an estimated 83% of dogs were registered that year with the Swedish Board of Agriculture and/or the Swedish Kennel Club dog registries, Mubanga and colleagues explain. They examined the Swedish national registry data to see how dog ownership was related to new CVD events or mortality.....This included 162,091 dog owners (4.8% of the population) and 3,195,153 people who were not dog owners.

Dog owners who lived alone or with at least one child or adult were less likely to die of CVD or all causes during follow-up compared with those who did not own a dog, but the relationships were stronger for solitary dwellers. Among dog owners, solitary dwellers (but not others) were also significantly less likely to have an MI or stroke than people who did not have a dog.