Low carbohydrate diets, also termed low carb diets, are nutritional dietary regimens that restrict the amount of ingested simple and complex carbohydrate in order to allow weight loss. Foods such as pasta, bread, cookies, and cake are kept to a minimum while increasing the amount of foods composed of protein and fat. Meat, chicken, seafood, eggs, seeds, and nuts are the predominant foods in a low carb diet.
Low carb diets are intended to cause a state of ketosis, which causes the body to switch from using glucose and glucogen to ketones as its primary energy source. Ketosis results in fat mobilization and breakdown because ketones become generated from fatty acids stored in fat cells. Dr. Robert Atkins is famous for having advocated a low carb diet, and the induction phase of the Atkins diet is intended to cause a state of ketosis.
Low carb diets have been criticized for possibly being detrimental to cardiovascular health due to the high fat content, which was theorized to raise cholesterol and triglyceride levels. In fact, more recent research suggests that carbohydrates may be more toxic to the cardiovascular system. We have previously discussed the toxic nature of sugar, and have also discussed the recent finding that diets high in fat and protein and low in carbohydrates allow weight that is lost to remain off and also allows an additional 300 calories to be burned during the day.
Researchers, led by Dr. William Yancy from Duke University Medical Center, have added to the evidence that low carb diets allow for weight loss and have beneficial effects on cardiovascular risk factors. The results of their research were published online in the journal Obesity Reviews. The researchers performed a systematic review and meta-analysis involving 17 clinical investigations that included 1,141 obese patients. The researchers found that low carb diets causes significant weight loss, and were associated with improvement of body mass index, waist circumference, systolic blood pressure, diastolic blood pressure, plasma triglycerides, fasting plasma glucose, glycated hemoglobin, plasma insulin, and plasma C-reactive protein (CRP), as well as increase in HDL cholesterol levels.
The authors wrote, “In conclusion, 23 reports, corresponding to 17 clinical investigations, were identified as meeting the pre-specified criteria. Meta-analysis showed [low carb diet] to be clearly associated with significant decreases in body weight, BMI, abdominal circumference, systolic blood pressure, diastolic blood pressure, plasma triglycerides, fasting plasma glucose, glycated haemoglobin, plasma insulin and plasma CRP, as well as with an increase in HDL-C. LDL-C and creatinine did not change significantly, whereas limited data were conflicted regarding plasma uric acid”.
The authors also wrote, “The long-term effects of [low carb diet], as well as the effects of [low carb diet] on clinical endpoints such as the incidence of myocardial infarction, stroke and total mortality, are essentially unknown and should be the object of future research”.
This study is important because it combines multiple previous studies into a meta-analysis and thus has more data to strengthen its conclusions. Low carb diets are clearly beneficial not only for losing weight, but also for improving cardiovascular risk. Obesity is becoming an increasingly bigger problem in the world and low carb diets should be recommended for weight loss for most people. There are some people that would not tolerate a low carb diet such as diabetics, so these types of diets would not be appropriate for everyone. The benefits of a low carb diet continue to be well documented by ongoing research.
F. L. Santos et al. “Systematic review and meta-analysis of clinical trials of the effects of low carbohydrate diets on cardiovascular risk factors” published online first August 20, 2012 Obesity Reviews doi: 10.1111/j.1467-789X.2012.01021.x