Even if you’re not overweight, cutting calories could lower inflammation by nearly 50 percent, improve other major risk factors for heart attack and stroke, including blood pressure and cholesterol, and even add years to your life, suggests a new National Institute on Aging (NIA) study.
The findings, which were published in Journal of Gerontology: Medical Science, “are quite intriguing,” said Evan Hadley MD, a study author and director of NIA’s division of geriatrics and clinical gerontology. “They show that this degree of sustained calorie restriction can influence disease risk factors and possible predictors of longevity in healthy, non-obese people.”
The study included 218 people ages 21 to 51, who were randomly assigned to either a calorie restriction group or a control group who followed their usual diets. At the start of the study, participants’ average body mass index (BMI) was 25.1, which is near the healthy range.
Those in the calorie-restriction group were given a weight-loss target of 15.5 percent in the first year, followed by sustaining the loss in the second year of the study. To achieve this goal, participants were expected to cut calories by 25 percent.
Significant Improvement in Predictors of Cardiovascular Risk
While the calorie-restriction group fell short of this goal, they did shed an average of 10 percent of their starting weight by cutting calories by 12 percent and maintained the loss during the second year–the largest sustained weight loss reported in any study of non-obese participants, according to the researchers.
Compared to the control group, whose weight and calorie intake was unchanged, the calorie-restriction group significantly lowered several predictors of risk for cardiovascular disease (CVD), the leading killer of American men and women. Among the outcomes were the following:
- A 47 percent drop in chronic inflammation, as measured by levels of high-sensitivity C-reactive protein (hsCRP). This protein, produced in the liver, rises when there’s inflammation in the body. As we recently reported, apparently healthy people with high levels of hsCRP are up to four times more likely to have heart disease. HsCRP and other inflammatory biomarkers can be measured with simple blood and urine tests.
- A 4 percent reduction in blood pressure. Not only is high blood pressure one of the leading risks for CVD, but even slight elevations boost the danger more than most patients realize. For example, a 2014 meta-analysis of studies involving more than 700,000 people found that those with prehypertension–blood pressure of 102/80 to 139/89–are 66 percent more likely to suffer a stroke than those with normal pressure, while risk doubles in those at the high end of this range.
- A 6 percent reduction in total cholesterol. The researchers also found that cutting calories improved levels of heart-protective HDL (good) cholesterol. High cholesterol is also a major risk factor for heart attack, but research shows that about half of those who suffer these events have normal cholesterol levels, highlighting the importance of working with your doctor to get more complete picture of your individual risk for heart attack and stroke.
- Striking reductions in insulin resistance (IR). Not only is IR the root cause of type 2 diabetes, but it also plays an important role in CVD. For example, a recent study of people hospitalized for acute coronary syndrome, 66 percent had previously undiagnosed diabetes. IR, which occurs when the body becomes less responsive to insulin produced by the pancreas, is also linked to increased levels of inflammatory biomarkers, including CRP, research suggests.
- A more than 20 percent drop in T3, a biomarker of thyroid hormone activity. This finding is intriguing because some studies suggest that lower thyroid activity may be linked to a longer life span, the researchers report.
The Downside of Cutting Calories
While cutting calories had a number of positive effects on risk factors for CVD and other chronic diseases in the study, a few participants in the calorie-restriction group developed temporary anemia or experienced greater-than-expected decreases in bone mass density given their amount of weight loss.
This finding reinforces the importance of medical supervision and monitoring of patients who are limiting calories, the researchers caution.
Talk to your medical provider about the best ways to assess your heart attack and stroke risk, and what steps you should take to maintain or achieve a healthy weight, such as improving your diet and exercising more.