The Keto Diet: Is it Worth It?

In the past three years, I have been asked for my thoughts on this diet more than any other topic.  Having specialized in pediatrics for the first four years of my career, I am very familiar with the ketogenic diet in the clinical space as a possible treatment for epilepsy.  Since then, it has become incredibly popular as a tool to support weight loss.  I’m hoping this post provides a succinct summary of the science and some RD-approved tips if you decide to give it a go. 

What is the “keto” diet? 

As a form of an extremely low carbohydrate diet, the ketogenic diet involves limiting carbohydrates to less than 50 grams per day.  For perspective, the Dietary Guidelines for Americans recommend that carbohydrates make up 40-65% of our daily caloric intake, which amounts to about 225-325 grams per day.  With carbohydrates so limited in the diet, fat becomes the primary macronutrient in the diet.  While fat and protein can be used as fuel for some organs, others such as the brain, heart and kidneys require glucose (derived from carbohydrates).  When glucose is unavailable due to a carbohydrate shortage, an alternate form of fuel is produced- ketones.  Once our body initiates this process of making ketones, it is deemed to be in ketosis.

How does it lead to weight loss?

Because it can be challenging to consume large amounts of fat, many people naturally reduce their intake, creating a caloric deficit.  A caloric deficit is crucial to drive weight loss.  While some can stick with it, others find it extremely challenging to eat this way in the long term.  Part of the initial rapid weight loss is also derived from fluid loss.  We store carbohydrates in our liver and muscles in the form of glycogen (see my sports nutrition post for more on this).  Glycogen naturally retains water, so in its absence, we lose the accompanying water.  There has also found to be an association with a small increase in energy expenditure, but this tends to dissipate with time (1).

Does it work for weight loss?

Many see quick results upon starting the diet; however, those promising results have been shown to dwindle at the one year mark.  When compared to a low fat diet, the science reveals that the difference in weight loss seen at six months was not sustained at 12 months (2). 

Is it safe?

Like any diet, the ketogenic diet can come with side effects.  In my pediatric clinical experience, we admitted children to the hospital for initiation of the diet.  Entering a state of ketosis can be associated with hypoglycemia, headache, halitosis (acrid smelling breath), muscle cramps, diarrhea and fatigue.  As an RD, I most commonly see the absence of fiber rich carbohydrates leading to constipation.  I also have concerns about micronutrient deficiencies due to the elimination of a food group (whole grains).  I highly recommend working alongside a physician and dietitian when giving a true ketogenic diet a try.

Is there a way to optimize the diet for long term health?

Because the ketogenic diet is high in fat, many professionals (myself include) express concern with the potential long-term effects associated with chronic disease risk.  I would highly recommend focusing on unsaturated fats and including plant-based protein. In fact, low carbohydrate diets with healthy choices for fat and protein may have some benefits for risk of type 2 diabetes, coronary heart disease and some cancers (3).

 As a quick reminder- healthy, unsaturated fats: nuts, seeds, oils (with the exception of tropical oils such as coconut), fish, avocado

In summary, I do not recommend the ketogenic diet unless used in the clinical setting for treatment of epilepsy.  With that being said, it’s your body, and you get to choose how you nourish it.  As a Mom, I’ll be the first to admit that sometimes you have to trust your gut and do what works best for you. With that being said, consider working with your doctor and dietitian for appropriate guidance and monitoring. 

1.     Hall, K. D., Chen, K. Y., Guo, J., Lam, Y. Y., Leibel, R. L., Mayer, L. E., ... & Ravussin, E. (2016). Energy expenditure and body composition changes after an isocaloric ketogenic diet in overweight and obese men. The American journal of clinical nutrition, 104(2), 324-333.

2.     Nordmann, A. J., Nordmann, A., Briel, M., Keller, U., Yancy, W. S., Brehm, B. J., & Bucher, H. C. (2006). Effects of low-carbohydrate vs low-fat diets on weight loss and cardiovascular risk factors: a meta-analysis of randomized controlled trials. Archives of internal medicine, 166(3), 285-293.

3.     Fung, T. T., van Dam, R. M., Hankinson, S. E., Stampfer, M., Willett, W. C., & Hu, F. B. (2010). Low-carbohydrate diets and all-cause and cause-specific mortality: two cohort studies. Annals of internal medicine, 153(5), 289-298.