Ketogenic diets: What the science says
- October 20, 2021
High intake of dietary fat is commonly believed, by both scientists and the general public, to cause obesity, diabetes, and cardiovascular disease. Although many Americans adhere to dietary guidelines that focus on reducing intakes of saturated and total fat, rates of many diet-related chronic diseases have markedly increased.
Ketogenic diets, which provide ≥ 70% of calories from fat, have been dismissed as fad weight-loss diets. However, ketogenic diets have a long history in clinical medicine and human evolution. Noting that ketogenic diets have elicited controversy, David Ludwig (New Balance Foundation Obesity Prevention Center, Boston Children’s Hospital and Harvard Medical School) provides a comprehensive review, published in The Journal of Nutrition, of evidence-based studies on the effects of ketogenic diets for a wide range of health conditions.
Ketogenic diets may be more effective than low-fat diets for the treatment of obesity and diabetes. In addition to the reductions in blood glucose and insulin achievable through carbohydrate restriction, chronic ketosis might confer unique metabolic benefits resulting in reduced risk of certain cancers, neurodegenerative conditions, and other diseases associated with insulin resistance. Based on available evidence, a well-formulated ketogenic diet does not appear to have major safety concerns for the general public and can be considered a first-line approach for obesity and type 2 diabetes.
High-quality clinical trials of ketogenic diets will further scientific understanding of long-term effects and their full potential in clinical medicine. Key unresolved questions that warrant further investigation include: How does LDL cholesterol elevation with carbohydrate restriction affect cardiovascular risk versus triglyceride elevation with fat restriction? Does the reduction in blood glucose and insulin on a ketogenic diet improve vascular health? Are there susceptible populations or conditions for which a ketogenic diet would be contraindicated? What is the efficacy of a ketogenic diet for long-term weight loss and behavioral change? Does chronic ketosis provide unique metabolic benefits, beyond those obtained by a low-glycemic index, moderate-carbohydrate diet?
References Ludwig DS. The Ketogenic Diet: Evidence for Optimism but High-Quality Research Needed. The Journal of Nutrition, Volume 150, Issue 6, June 2020, Pages 1354–1359, https://doi.org/10.1093/jn/nxz308.
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