Too much belly fat, even for people with a healthy BMI, raises heart risks

People with too much fat around their midsections and vital organs are at increased risk for heart disease, even if their body mass index falls within what is considered a healthy range, according to a new scientific report.

The statement from the American Heart Association, published Thursday in its journal Circulation, summarizes research on the ways in which belly fat and other measures of obesity affect heart health. Belly fat also is referred to as abdominal fat and visceral adipose tissue, or VAT.

“Studies that have examined the relationship between abdominal fat and cardiovascular outcomes confirm that visceral fat is a clear health hazard,” writing committee chair Dr. Tiffany Powell-Wiley said in a news release. Powell-Wiley is chief of the Social Determinants of Obesity and Cardiovascular Risk Laboratory at the National Heart, Lung, and Blood Institute in Bethesda, Maryland.

Whether a person has too much belly fat is typically determined using the ratio of waist circumference to height (taking body size into account) or waist-to-hip ratio. This measurement has been shown to predict cardiovascular death independent of BMI, a measure of obesity that is based on height and weight.

Experts recommend both abdominal measurement and BMI be considered during regular health care visits because even in healthy weight individuals, it could mean an increased heart disease risk. Abdominal obesity is also linked to fat accumulation around the liver. That often leads to non-alcoholic fatty liver disease, which adds to cardiovascular disease risk.

Worldwide, around 3 billion people are overweight or have obesity. The “obesity epidemic contributes significantly” to many chronic health conditions and cardiovascular disease cases around the world, Powell-Wiley said. Specifically, obesity is associated with a higher risk of coronary artery disease and death from cardiovascular disease. It contributes to high cholesterol, Type 2 diabetes, high blood pressure and sleep disorders.

Yet some people whose BMI classifies them as obese, but who have low levels of abdominal fat, are at lower risk for heart problems, the analysis showed.

Meeting federal guidelines for 150 minutes of physical activity per week may be sufficient to reduce abdominal fat, the analysis found, with no additional loss from longer activity times. Exercise alone or in combination with diet changes have been shown in some instances to reduce abdominal obesity even without weight loss.

Also, weight loss from lifestyle changes improves blood sugar, blood pressure, and triglyceride and cholesterol levels – a cluster of factors referred to as metabolic syndrome, according to the new statement. It also reduces inflammation, improves blood vessel function and helps non-alcoholic fatty liver disease.

In addition, intense weight loss may help curb atrial fibrillation, a quivering or irregular heartbeat, according to the report. Estimates suggest obesity may account for one-fifth of all cases.

The new scientific statement evaluated research on managing and treating obesity, particularly abdominal obesity. Experts concluded that reducing calories and aerobic exercise were the most beneficial.

Bariatric weight loss surgery has been shown to reduce the risk for coronary artery disease better than weight loss achieved without surgery. This may be due to the larger amount of weight loss achieved with surgery and the resultant changes in metabolism that are typical after bariatric surgery.

The statement also addresses what’s known as the “obesity paradox.” That is, even though overweight and obesity are strong risk factors for cardiovascular disease, in the short-term, they don’t always mean patients have worse survival outcomes. The analysis concludes this may be because people classified as overweight or obese are often screened earlier for cardiovascular disease than people with healthy weight, so they are diagnosed and treated earlier.

“The underlying mechanisms for the obesity paradox remain unclear,” Powell-Wiley said. “Despite the existence of the paradox for short-term cardiovascular disease outcomes, the data show that patients with overweight or obesity suffer from cardiovascular disease events at an earlier age, live with cardiovascular disease for more of their lives and have a shorter average lifespan than patients with normal weight.”

Article published courtesy of American Heart Association News

Breastfeeding may reduce type 2 diabetes risk among women with gestational diabetes, NIH study suggests

The longer a woman with gestational, or pregnancy-related, diabetes breastfeeds her infant, the lower her risk for developing type 2 diabetes later in life, suggests an analysis by researchers at the National Institutes of Health and other institutions.

The study was conducted by Cuilin Zhang, M.D., Ph.D., of NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), and colleagues. It appears in Diabetes Care.

In addition to health risks for mothers and babies, gestational diabetes increases the risk for type 2 diabetes 10 to 20 years after pregnancy. Type 2 diabetes increases the risk for heart disease, stroke and other health problems.

The researchers analyzed data from the Nurses’ Health Study II, a long-term study of risk factors for chronic diseases in women. Of more than 4,000 women in the study who had gestational diabetes, 873 developed type 2 diabetes over the course of 25 years. Compared to women with gestational diabetes who had not breastfed, those who breastfed for six to 12 months were 9% less likely to develop type 2 diabetes, those who breastfed for one to two years were 15% less likely, and those who breastfed for more than two years were 27% less likely.

The researchers suggested that clinicians may want to encourage patients with gestational diabetes to breastfeed if they are able to, to potentially reduce their type 2 diabetes risk.

The analysis was funded by NICHD with additional support from NIH’s National Institute of General Medical Sciences.

vitamin D does not prevent type 2 diabetes in people at high risk – Study finds

Taking a daily vitamin D supplement does not prevent type 2 diabetes in adults at high risk, according to results from a study funded by National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health. 

Observational studies have reported an association between low levels of vitamin D and increased risk for type 2 diabetes

The Vitamin D and Type 2 Diabetes (D2d) study enrolled 2,423 adults and was conducted at 22 sites across the United States. These findings were published in the New England Journal of Medicine and presented at the 79th Scientific Sessions of the American Diabetes Association in San Francisco.

D2d(link is external) is the largest study to directly examine if daily vitamin D supplementation helps keep people at high risk for type 2 diabetes from developing the disease. The study included adults aged 30 or older and assigned participants randomly to either take 4,000 International Units (IU) of the D3 (cholecalciferol) form of vitamin D or a placebo pill daily. All study participants had their vitamin D levels measured at the start of the study. At that time, about 80% of participants had vitamin D levels considered sufficient by U.S. nutritional standards.

“Observational studies have reported an association between low levels of vitamin D and increased risk for type 2 diabetes,” said Myrlene Staten, M.D., D2d project scientist at NIDDK. “Additionally, smaller studies found that vitamin D could improve the function of beta cells, which produce insulin. However, whether vitamin D supplementation may help prevent or delay type 2 diabetes was not known.”

The study screened participants every three to six months for an average of 2.5 years to determine if diabetes had developed. Researchers then compared the number of people in each of the two study groups that had progressed to type 2 diabetes. At the end of the study, 293 out of 1211 participants (24.2%) in the vitamin D group developed diabetes compared to 323 out of 1212 (26.7%) in the placebo group – a difference that did not reach statistical significance. The study was designed to detect a risk reduction of 25% or more.

D2d enrolled a diverse group of participants with a range of physical characteristics, including sex, age, and body mass index, as well as racial and ethnic diversity. This representation helps ensure that the study findings could be widely applicable to people at high risk for developing type 2 diabetes.

“In addition to the study’s size, one of its major strengths is the diversity of its participants, which enabled us to examine the effect of vitamin D across a large variety of people,” said lead author Anastassios G. Pittas, M.D., principal investigator from Tufts Medical Center, Boston. “When the study ended, we found no meaningful difference between the two groups regardless of age, sex, race or ethnicity.”

More than 50% of adults in the United States take nutritional supplements and use of vitamin D has increased substantially over the last 20 years. Because of these trends, the study also evaluated the safety of taking 4,000 units of vitamin D daily — greater than the average daily recommended dose of 600-800 IUs a day, but within limits deemed appropriate for clinical research by the Institute of Medicine. The researchers saw no difference in the number and frequency of predicted side effects such as high blood calcium levels and kidney stones when they compared the vitamin D and placebo groups. 

“As we learned from the NIDDK-funded Diabetes Prevention Program (DPP), type 2 diabetes is not a foregone conclusion, even for those at high risk for the disease,” said NIDDK Director Griffin P. Rodgers, M.D. “While we continue to search for new ways to prevent the disease, we know that lifestyle change or the drug metformin remain effective methods to prevent type 2 diabetes. We encourage the 84 million U.S. adults at high risk for developing type 2 diabetes to explore options like the CDC’s National DPP, available to communities throughout the country.”