Ketogenic Diets: Fact or Fad?

Recent data link animal protein consumption with prostate cancer, diabetes, and early death

Low-carbohydrate and very low-carbohydrate (also known as ketogenic) regimens are popular for those seeking quick weight loss, lower cholesterol levels, and improved diabetes management. These eating habits limit carbohydrate intake to 30 grams or less per day in some programs to achieve ketosis.1 When the body can no longer rely on carbohydrate, it looks toward body fats and protein for energy, which may lead to weight loss.2 Unfortunately, there are serious risks involved in carbohydrate-restricted diets.

When there is not enough carbohydrate to carry glucose to the cells, the body forms ketones (an emergency energy source) from fatty acids as a replacement. This increases the body’s acidity, resulting in metabolic acidosis, which may lead to low blood phosphate levels, decreased brain function, and increased risk for osteoporosis and kidney stones.3 Ketogenic diets have also been shown to induce a higher percentage of headaches, halitosis, constipation, diarrhea, general weakness, rash, insomnia, and back pain among study participants.4

These diets often call for high-protein foods, including meat, poultry, and dairy.5 Consequently, they score low on the Alternative Healthy Eating Index—a measure of how effective eating patterns are in preventing chronic diseases—due to low consumption of fruits, vegetables, whole grains, and legumes and a higher intake of red meat and trans fatty acids.6 The literature emphasizes the need for further investigation of what happens when people eat this way for a prolonged period. Many clinical trials on the subject center on short-term trials and cannot account for long-term effects. This concerns researchers who worry people will adopt these eating habits as a way to lose a few pounds without considering the risks for chronic diseases.

Recent data link animal protein consumption with prostate cancer, diabetes, and early death.7 A study from 2012 saw a 5 percent increase of cardiovascular disease risk when participants lowered carbohydrate and consumed more animal protein.8 For a healthful approach to disease prevention, focus on plant-based, nutrient-dense foods rich in fiber that provide a wide array of protective antioxidants, vitamins, and phytochemicals.


  1. Brehm BJ, Seeley RJ, Daniels SR, D’Alessio DA. A randomized trial comparing a very low carbohydrate diet and a calorie-restricted low fat diet on body weight and cardiovascular risk factors in healthy women. J Clin Endocrinol Metab. 2003;88:1617-1623.
  2. Saslow LR, Kim S, Daubenmeir JJ, et al. A randomized pilot trial of a moderate carbohydrate diet compared to a very low carbohydrate diet in overweight or obese individuals with type 2 diabetes mellitus or prediabetes. PLos One. 2014;9:e91027.
  3. Groff JL, Gropper SS, Hunt SM. Advanced Nutrition and Human Metabolism. 2nd ed. West Publishing Company, 1995; Wiederkehr M, Krapf R. Metabolic and endocrine effects of metabolic acidosis in humans. Swiss Med Wkly. 2001;131:127–132.
  4. Westman EC, Yancy WS Jr, Mavropoulos JC, Marquart M, McDuffie JR. The effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitus. Nutr Metab. 2008;5.
  5. Jardine M. T05. Presented at: The American Association of Diabetes Educators Annual Meeting 2014; August 6-9, 2014; Orlando, FL.
  6. Ma Y, Pagoto SL, Griffith JA, et al. A dietary quality comparison of popular weight-loss plans. J Am Diet Assoc. 2007;107:1786-1791.
  7. Levine ME, Suarez JA, Brandhorst S, et al. Low protein intake is associated with a major reduction in IGF-1, cancer, and overall mortality in the 65 and younger but not older population. Cell Metab. 2014; 19:407-417; Sourbeer KN, Howard LE, Andriole GL, Moreira DM, Freedland SJ, Vidal A. Etabolic syndrome components and prostate cancer risk: results from the Reduce study. Presented at: American Urological Association 2014 Annual Meeting; May 20, 2014: Orlando, Fla; Van Nielen M, Feskens EJM, Mensink M, et al. Dietary protein intake and incidence of type 2 diabetes in Europe: the EPIC-INTERACT case-cohort study. Diabetes Care. Published ahead of print April 10, 2014.
  8. Lagiou P, Sandin S, Lof M, Trichopoulos D, Adami HO, Weiderpass E. Low carbohydrate-high protein diet and incidence of cardiovascular diseases in Swedish women: prospective cohort study. BMJ. 2012;344:e4026.

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