Inflammation has become increasingly recognized as contributing to the development of heart disease and stroke. Inflammation increases the risk of atherosclerotic plaque formation, blood clot formation, and decreases the ability of blood vessels to contract and relax normally. Obesity is known to be a high inflammatory state, and the increased risk of heart disease that is associated with obesity is thought to occur from the high levels of inflammation that occur in obesity. We have previously discussed the finding that physical activity decreases inflammatory markers associated with cardiovascular disease and aging. Recent research has shown that weight loss using either a low carb or low fat diet decreases inflammation and heart disease risk.
Researchers, led by Dr. Kerry J. Stewart from the Johns Hopkins University School of Medicine, have shown that weight loss helps decrease markers of inflammation that are associated with heart disease. The results of the research were presented at the American Heart Association Scientific Sessions in Los Angeles on November 5, 2012. The researchers recruited 60 healthy but overweight or obese individuals into the study. The study participants followed a low carbohydrate or low fat diet for a 6 month period in combination with physical exercise three times per week. At study start and finish the study participants were evaluated for inflammatory markers that included C reactive protein, interleukin 6, and tumor necrosis factor alpha. In addition, the study participants had measurements of body weight, body mass index (BMI), total body fat, and belly fat.
The study participants on the low carbohydrate diet lost more weight than those on the low fat diet – 28 pounds versus 18 pounds. In addition, the study participants on the low carbohydrate diet decreased their BMI by 4.7 points compared to 2.9 points for the low fat diet participants. Belly fat decreased in both groups also but the low carbohydrate group lost more than the low fat group – 14.3 pounds versus 8.4 pounds. The aerobic fitness increased in both groups by about the same amount – 20%. Markers of inflammation (C reactive protein, interleukin 6, and tumor necrosis factor alpha) decreased in both groups which suggest that heart disease risk had also decreased.
The authors wrote, “Both groups reduced systemic inflammation, reduced total and central obesity, and increased fitness, with greater losses in weight, BMI, and total body fat occurring in the low-[carbohydrate] group. A key finding was no group difference in the reduction in systemic inflammation, suggesting that a lifestyle intervention that includes a low-[carbohydrate] diet improved inflammatory responses similar to a low-fat diet”.
This study has not been published in a peer reviewed journal and should be considered preliminary. In addition, this study will need to be reproduced on a larger scale. Despite this, the findings of this study are encouraging and are in line with previous research findings that we have discussed. We have previously discussed the finding that low carb diets result in more initial weight loss compared to low fat and Mediterranean diets. This study contributes vital information on the beneficial effect of decreasing inflammation by weight loss. Weight loss, particularly belly fat loss, is very important for decreasing inflammation and cardiovascular disease risk. Future studies should focus on improvements in long term outcomes, such as heart attack and stroke rates, as a result of weight loss that decreases inflammation.
Kerry J. Stewart et al. “Reductions in Systematic Inflammation After a Low-Carbohydrate Diet versus a Low-Fat Diet Each Combined with Exercise” American Heart Association Scientific Sessions 2012, Presentation 17578, Monday, Nov 05, 2012