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Low-carbohydrate diet claims scrutinized

The National Lipid Association has issued a statement based on a comprehensive review of recent systematic reviews and meta-analyses on the effects of low- and very-low-carbohydrate diets on body weight, lipoprotein levels, blood sugar levels, and other risk factors for cardiovascular and metabolic diseases. [Kirkpatrick CF. and others. Review of current evidence and clinical recommendations on the effects of low-carbohydrate and very-low-carbohydrate (including ketogenic) diets for the management of body weight and other cardiometabolic risk factors. Journal of Clinical Lipidology 13:689-711, 2019] The statement's key conclusions include:

• Low-carbohydrate diets are not superior to other weight-loss diets. They may have advantages for appetite control, triglyceride reduction, and reduction in use of diabetes medication, but they do not persist after about 2 years.


• The evidence is mixed concerning effects on low-density lipoprotein cholesterol levels, with some studies showing increasing levels of these diets.

• It is unclear that they have advantages related to other risk markers for cardiovascular and metabolic diseases.


• Initial weight loss on these diets is primarily due to loss of body water.


• Weight loss with carbohydrate restriction appears to result in greater loss of lean body mass than with more balanced low-calorie diets.


• Less lean body mass may be lost during weight loss on low-carbohydrate diets when protein consumption is higher.


• Three observational studies, including a large one with long-term follow-up, have found that a very low carbohydrate intake is associated with increased risk of dying.


• Maintaining very-low-carbohydrate diets is challenging and has the potential to cause adverse side effects.


• Very-low-carbohydrate diets severely restrict or eliminate foods associated with heart health benefits and encourage a high intake of foods known to increase atherosclerotic cardiovascular disease risk such as processed meats and foods rich in saturated fatty acids.