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The “ketogenic diet,” or “keto” for short, has become a household staple across the United States. The low-carbohydrate diet craze has been featured on tabloids and other forms of media across the nation for decades now. It has survived and metamorphosized into different manifestations—the Atkins diet, the Zone diet, the Paleo diet, the South Beach Diet, and many other low-carb or keto diets iterations. Besides its status as a “fad” diet, the keto diet has been studied in nutritional science for its application in several diseases and weight loss. Let’s review and see what the science says about it.

Weight Loss

If there is one reason the keto diet has been popular, it has been for its purported benefits in weight loss. Proponents of the diet swear by its ability to melt pounds. However, a big issue that the scientific community has recognized is maintaining the diet long-term and separating the effects of lower calorie intake, which is typical for individuals transitioning to a low-carb or keto diet. Transitioning to a dietary lifestyle that essentially cuts out an entire macronutrient group (of which there are three: carbohydrates, protein, and fats—the components in food that provide calories) will lead to decreased caloric intake (1). For this reason, it is said that ketogenic diets are very successful in spurring rapid weight loss when a person adopts this eating style (2).

Unfortunately, many studies looking at the success of keto diets for weight loss are relatively short-term (with a maximum of a couple of weeks). Long-term studies have reported that keeping low-carb for the long run may prove difficult (3). This difficulty does not discount the value a low-carb diet has for weight loss, though it is essential to understand that keeping low-carb all the time is unfeasible. This is the likely reason why many proponents of low-carb or keto diets recommend “cycling” or going through periods of low-carb eating and then switching to a regular pattern of eating (4). 

Low Carbohydrate Diets and Disease

The study of keto diets in cardiovascular disease has yielded interesting results. At the forefront are the findings showing that consuming a ketogenic diet may increase HDL and LDL cholesterol (5,6). HDL cholesterol will colloquially be referred to as “good cholesterol,” whereas LDL cholesterol is perceived as “bad cholesterol.” Higher LDL levels increase one’s risk of cardiovascular disease, while higher HDL levels are understood to lower one’s risk of cardiovascular illness.

Several other links between low-carb diets and health markers have been discovered in the scientific community. It is important to not only consider whether a diet is low-carb but also if it is comprised of healthy foods. Consumption of healthy foods is, perhaps, more important than the carbohydrate, fat, or protein composition of the diet. A recent study of over 37,000 U.S. adults found that unhealthy low-carbohydrate diets increased one’s risk of death while healthy low-carbohydrate diets actually reduced the risk of death (7).

Another study found that a low-carbohydrate diet rich in vegetable sources of fat and protein decreased the risk of type 2 diabetes (8). Another recent monumental study that looked at data from thousands of four diverse communities in the U.S. found that very low carbohydrate diets and very high carbohydrate diets increased the risk of death (9). More importantly, they clarified that individuals following low-carb diets with healthier food compositions had better outcomes than those with unhealthy low-carb diets. This evidence, again, stresses the importance of the type of foods in a diet rather than just the mere number of carbohydrates one consumes.

Summarizing Low Carbohydrate Diets

In sum, the role of low-carb or keto diets has been studied by researchers. Its value for weight loss has been made. In the short term, it may spur good weight loss (10). However, more important than the macronutrient composition of the diet one consumes are the foods one eats, especially when it comes to health. The evidence has shown that we should be monitoring the foods that we eat rather than obsessing over the number of carbohydrates we ate. A healthy diet rich in vegetables and fruits that minimizes processed foods is likely to deliver good results for many. Even in the low-carb world, eating greater amounts of vegetables was more important than simply striving for lower carbohydrates.

For more information on Keto diets, join us for our upcoming webinar UNDERSTANDING THE HYPE: EMERGING EVIDENCE FOR THE USE OF THE KETOGENIC DIET IN CHRONIC DISEASE, Tuesday, July 20,11:00 am ET.

  1. Johnstone AM, Horgan GW, Murison SD, Bremner DM, Lobley GE. Effects of a high-protein ketogenic diet on hunger, appetite, and weight loss in obese men feeding ad libitum. Am J Clin Nutr. 2008 Jan 1;87(1):44–55.
  2. Soenen S, Bonomi AG, Lemmens SGT, Scholte J, Thijssen MAMA, van Berkum F, et al. Relatively high-protein or ‘low-carb’ energy-restricted diets for body weight loss and body weight maintenance? Physiol Behav. 2012 Oct;107(3):374–80.
  3. Willoughby D, Hewlings S, Kalman D. Body Composition Changes in Weight Loss: Strategies and Supplementation for Maintaining Lean Body Mass, a Brief Review. Nutrients. 2018 Dec 3;10(12):1876.
  4. Fife B. Keto Cycling: How to Optimize the Ketogenic Diet and Avoid Common Mistakes.
  5. Sumithran P, Proietto J. Ketogenic diets for weight loss: A review of their principles, safety and efficacy. Obes Res Clin Pract. 2008 Mar;2(1):1–13.
  6. Bueno NB, de Melo ISV, de Oliveira SL, da Rocha Ataide T. Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. Br J Nutr. 2013 Oct;110(7):1178–87.
  7. Shan Z, Guo Y, Hu FB, Liu L, Qi Q. Association of Low-Carbohydrate and Low-Fat Diets With Mortality Among US Adults. JAMA Intern Med. 2020 Apr 1;180(4):513.
  8. Halton TL, Liu S, Manson JE, Hu FB. Low-carbohydrate-diet score and risk of type 2 diabetes in women. Am J Clin Nutr. 2008 Feb 1;87(2):339–46.
  9. Seidelmann SB, Claggett B, Cheng S, Henglin M, Shah A, Steffen LM, et al. Dietary carbohydrate intake and mortality: a prospective cohort study and meta-analysis. Lancet Public Health. 2018 Sep;3(9):e419–28.
  10. Ebbeling CB, Feldman HA, Klein GL, Wong JMW, Bielak L, Steltz SK, et al. Effects of a low carbohydrate diet on energy expenditure during weight loss maintenance: randomized trial. BMJ. 2018 Nov 14;k4583.

Author: Christian Maino Vieytes, Doctoral Student, The University of Illinois at Urbana-Champaign

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