The Keto Diet: Is It Really Healthy?
June 18, 2019
By Registered Dietitian, Carla Yaldezian-Estrada, MS, RD – CareerSmart® Learning Contributor
The ketogenic or “keto” diet is a low-carbohydrate, high-fat eating pattern. The keto diet is gaining popularity for its potential weight loss benefits. The diet is like other low-carbohydrate diets such as Atkins, South Beach, or Paleo in that the carbohydrate intake is very low – less than 50 grams per day (which is about the amount found in one cup of oats) – but the emphasis is on fat, not protein. The keto diet works to deprive the body of glucose, which is our body’s primary source of energy. Carbohydrates provide the primary source of glucose, but when the body is in a carbohydrate deficit it will first pull stored protein from our muscles to use as fuel. If the deficit continues, the body will resort to alternative fuel sources called ketones to supply the body with energy. The liver produces ketone bodies from stored fat. This change in the body’s metabolism is called ketosis (thus, the term “keto”-genic). Weight loss is achieved as the body continues to burn body fat to make ketones.
As there appear to be different variations of the keto diet, most studies have examined macronutrient breakdown averaging anywhere from 70-80% fat from total daily calories, 5-10% carbohydrate, and 10-20% protein2. For example, a 2000-calorie diet is translated into 25-50 grams carbohydrate, 50-100 grams protein, and 165-177 grams fat2. The 2015-2020 Dietary Guidelines for Americans Acceptable Macronutrient Distribution Range or AMDR for fat is 20-30% from total daily calories5. So, a keto diet requires more than double the recommended amount of fat. In order to consume about 165 plus grams of fat every day, one could indulge in all the bacon, steaks, salami, and butter they want. Therefore, not only is the keto diet high in fat, but the source of fat tends to include more saturated fat. Other unsaturated fats such as nuts, seeds, avocados, plant oils, and oily fish are also allowed. This raises a concern as it conflicts with The American Heart Association which recommends limiting saturated fats to no more than 5-6% of your daily calories because of the link to heart disease1. Since limiting carbohydrate intake is the key to ensuring ketosis is maintained in a keto diet, it can be challenging to fit in a balance of whole grains, fruits, and starchy vegetables. Thus, the keto diet emphasizes fat intake, while neglecting vital nutrients like fiber, antioxidants, and phytonutrients – all of which have been proven to be essential in preventing chronic diseases5.
Although ketogenic diet studies have shown accelerated weight reduction, there have been no differences found past year-one of the diet compared to calorie-controlled diet plans4. Therefore, no long-term benefits have been shown to endorse the keto diet as a strategy in combating the obesity epidemic. In fact, the negative side effects of the keto diet may outweigh the positive weight loss results. Some studies have found prolonged exposure of our muscles to high levels of fat can lead to severe insulin resistance, with saturated fats demonstrated to be the worst3. Not only does it pose the risk of developing insulin resistance but also heart disease, fatty liver, and possible kidney insufficiency2, 4. Also, many individuals on a keto diet report substantial adherence issues as the pool of food choices becomes tedious and invariable due to the tight carbohydrate restrictions. These barriers tend to cause individuals to give up or fall into the “yo-yo” effect of dieting. In daily practice, it appears the ketogenic diet is limited to a short-term weight loss method – a minimum of 2-3 weeks to initiate ketosis to a maximum of 6 to 12 months – and geared for those individuals that are interested in losing a small to moderate amount of weight quickly. Rather, consider an eating plan that balances carbohydrate, protein, and fat while controlling calorie intake as this provides more long-term sustainability and promotes a realistic transition to a lifestyle change.
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1. American Heart Association. (2015, June 1). Saturated Fat. Retrieved from American Heart Association: https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/fats/saturated-fats
2. Harvard School of Public Health. (2019, January 1). Diet Review: Ketogenic Diet for Weight Loss. Retrieved May 28, 2019, from Nutrition Source: https://www.hsph.harvard.edu/nutritionsource/healthy-weight/diet-reviews/ketogenic-diet/
3. NutritionFacts.org. (2017, January 6). What Causes Insulin Resistance. Retrieved May 28, 2019, from NutritionFacts: https://nutritionfacts.org/video/what-causes-insulin-resistance/
4. Paoli A. (2014). Ketogenic diet for obesity: friend or foe? International journal of environmental research and public health, 11(2), 2092–2107. doi:10.3390/ijerph110202092
5. U.S. Department of Health and Human Services and U.S. Department of Agriculture. 2015–2020 Dietary Guidelines for Americans. 8th Edition. December 2015. Available at http://health.gov/