A new research shows that losing weight without decreasing muscle mass results in a substantially lower risk of heart failure in people with type 2 diabetes.
In the United States, about 1 in 10 people have diabetes, and 90–95 percent of them have type 2 diabetes. Type 2 diabetes typically progresses after age 45. Estimates indicate that by 2045, 700 million adults worldwide would have this disease.
Type 2 diabetes typically starts as insulin resistance. This is a disorder wherein the body’s cells no longer respond to the insulin the pancreas produces to regulate blood sugar.
Genetics, ethnicity, and advancing age all play a role in the development of insulin resistance and diabetes. However, body weight, a lack of exercise, an unhealthful diet, and smoking can be driving factors in its incidence.
Once physicians diagnose this disorder, the main remedies they advise usually include taking drugs and making some lifestyle changes, such as losing weight and changing the diet.
As diabetes nearly doubles the risk of death due to heart disease or stroke and raises the risk of developing heart failure by a factor of two in males and five in females, several studies are focused on avoiding these and related health risks for those with diabetes.
Heart failure, or congestive heart failure, occurs when the heart muscle does not pump the blood properly. This leads to an accumulation of fluid in the lungs or legs, or sometimes both.
Heart failure has a variety of possible causes. For example, after a heart attack (when the heart muscle sustains damage due to a lack of oxygen), the muscle is weak and cannot pump well.
Heart failure can also occur due to type 2 diabetes. This is due to the direct damage of increased blood sugar and systemic inflammation associated with the disease to the heart muscle.
One preventive technique requires weight loss for people who are overweight or obese. Not much is clear, however, on what form of weight loss has the greatest effect on reducing the risk of heart problems linked to diabetes.
The study
Researchers at the University of Texas Southwestern Medical Center (UTSW) in Dallas analyzed data from the Look AHEAD report to explore this further.
This is a randomized study that examines weight loss in individuals with type 2 diabetes due to intense lifestyle intervention, consisting of healthy food and increased physical activity over support and education alone.
Support from the National Heart, Lung, and Blood Institute, the Texas Health Services Clinical Scholars Network, and the National Institutes of Health (NIH) was given for the UTSW report, which appears in the journal Circulation.
At the start of the study, the researchers picked 5,103 individuals from the Look AHEAD study who did not have heart failure. In order to estimate how much fat mass and lean (muscle) mass they had the participants also had enough baseline measurements needed for prediction equations.
At the beginning of the study and over a 4-year period, data was available on the weight and waist circumference of the participants. The team also observed hospitalizations over a 12-year time span for heart failure.
257 research participants were hospitalized for heart failure therapy during the 12-year follow-up of the experiment.
Scientists used a scanning technique called dual-energy X-ray absorptiometry (DXA) in the Look AHEAD analysis to assess body composition in a subset of around 1 in 5 of the respondents. Information on factors such as height, weight, waist circumference, and ethnicity was also reported for these participants.
This meant that the researchers were able to validate existing equations that predict the proportion of fat mass and lean mass from these variables, which are easy to gather compared to the much more complicated DXA scan technique.
A new equation unique to this study group was given by the researchers’ review of the subset of participants with DXA scans. Without a DXA scan, they applied this new equation to the remaining participants to estimate their fat mass and lean mass accurately.
This showed that if they decreased their fat mass and waist circumference, adults in the study who had lost weight were less likely to experience heart failure. However, their risk was not changed by losing lean mass.
The researchers note that while the risk of heart disease decreased in those who lost body fat and lowered their waist circumference, there was no substantial reduction in the risk of heart attack in the study results.
The team also considered the ejection fraction (EF) ratio of the participants. This is a calculation of the amount of blood that with each contraction leaves the heart.
The data showed that decreasing body fat mass by 10 percent resulted in a 22 percent lower risk of retained EF ratio heart failure and a 24 percent lower risk of decreased EF ratio heart failure.
“Our study suggests that simply losing weight is not enough. We may need to prioritize fat loss to truly reduce the risk of heart failure.”
– Study co-author Dr. Kershaw Patel, a cardiologist at Houston Methodist Hospital in Texas
Supporting evidence
A May this year study that appears in the Circulation Research journal compared phenotypes of obesity, diabetes and cardiovascular diseases.
The comparison indicates that there is a greater risk of diabetes and heart disease in certain individuals who have a good weight or overweight but an excess amount of fat deposits around the internal organs and under the skin.
The researchers suggest that the risk of cardiovascular disease and type 2 diabetes can not be determined on the basis of body mass index (BMI) alone, mainly because the composition of the body is so complex.
They propose that because cardiovascular risks are primarily characterized by excessive quantities of fat tissue, reducing body fat is important for prevention.
Implications and limitations
The findings of the UTSW study indicate that in general, losing weight might not be sufficient to minimize the risk of heart health for people with diabetes who are also overweight.
If more studies reproduce these results, it could confirm that a key factor in lowering the risk of heart failure in type 2 diabetes is losing weight by shedding visceral fat from around the organs instead of losing muscle mass.
The study authors also suggest that more research is important to decide if building or preserving muscle will be even more successful in reducing the risk of diabetes-related heart failure in addition to losing fat mass.
