New High Fat Weight Loss Diet Raises CRP

Despite the media hype of several studies suggesting that a high-fat, Atkins-style (HF) diet does not adversely affect blood lipids and other cardiovascular (CVD) risk factors, all of these studies had very poor compliance. Simply put, the subjects had pretty much reverted to their own original before the studies ended.

By contrast, when people actually stick with HF ketogenic diets, blood lipids and most other CVD risk factors generally worsen. For example,Dr. Kwiterovich observed in children who must closely adhere to a very HF ketogenic diet to control their epilepsy that LDL increased 49%, triglcerides increased 60%, and HDL fell 12% from where these levels were when these children were eating a typical American diet.1Another study, which reported good compliance with two high-carbohydrate (HC) diets and a HF diet, was conducted by Dr. Fleming.2 Dr. Fleming reported dramatic improvements in blood lipids after 1 year on the two HC diets (LDL-C droped38.8 and -52.1%). By contrast, on the HF diet LDL-C increased 6.0% despite the loss of 13.7% of their initial body weight. Dr. Fleming looked at other CVD risk factors such as fibrinogen levels and Lp(a), which also worsened on the HF diet but improved on the HC diet despite a similar loss of body weight.One very important CVD risk factor Dr. Fleming did not measure was c-reactive protein (CRP), a blood marker for chronic low levels of inflammation. Over a 5-year period CRP predicts CVD events about as well as blood lipid values do.A recent study of a potent statin drug in people who had elevated (>2.0) CRP levels but LDL less than 130mg/dl found that the drug not only lowered total and LDL cholesterol levels (by 50%) but also reduced CRP levels by 37% on average after 19 months. Compared to the placebo group, those receiving the statin experienced about a 50% reduction in CVD events.3 The authors of this study believe that part of the way statins reduce CVD events is by reducing inflammation as measured by CRP levels.CRP promotes inflammation in the body, which markedly increases the risk of CVD events. Obese people tend to have higher levels of CRP, in part because bigger fat cells make more CRP and interlukin-6 that triggers the liver top make more CRP as well. A study by Dr. Rankin and Turpyn at Virginia Tech fed 29 mostly obese (BMI = 32.1) women either an Atkins-style HF diet or a HC for 4 weeks.4 Compliance on the HF and LC diets was reasonably good using these percents of macronutrients:On the HF diet, subjects lost an average of 8.36 pounds compared to 5.72 pounds on the HC diet. However, despite the somewhat greater loss of body weight on the HF diet, CRP levels increased by 25% on average while CRP levels on the HC diet plummeted 43% in just 4 weeks.Bottom Line:When compliance with an Atkins-style, HF diet is good, researchers have consistently shown marked increases in a wide variety of CVD risk factors even when significant weight loss also occurs. By contrast, blood lipids and other known and suspected CVD risk factors nearly all improve dramatically on very-low-fat, high-fiber diets even if little or no weight is lost. At the very least health professionals should be leery about supporting the use of a HF Atkins-style diet, which almost certainly in the long-term would markedly increase the risk of CVD even if it resulted in weight loss.

By James J. Kenney, PhD, RD, FACNReferences:1. JAMA 2003;290:912-202. Prev Cardiol 2002;5:110-83. N Engl J Med 2008;359:2195-2074. J Am Coll Nutr 2007:26;163-9