By Megan Holt, DrPH, MPH, RD
The ketogenic diet is another iteration of a low-carbohydrate, high fat diet. While the diet appears to have experienced a rise in popularity over the past couple of years, it was actually coined by a physician, Russel Wilder, from Mayo Clinic, back in 1921.
Carbohydrates from food are a primary substrate for glucose, but in this particular instance, the liver is forced to use fat for fuel, which is then converted to ketone bodies.
Dr. Wilder was aiming to induce ketosis through the diet, which is a metabolic state within which the body must rely on ketone bodies as a primary energy source in the absence of glucose.
A ketogenic diet has been used in pediatric populations for several decades, as there is evidence to support a subsequent reduction in seizure activity in children with epilepsy, though concerns around adequate calorie provision, stunted growth and development of effective medications for epilepsy resulted in a decline in its use. Evidence has been less compelling among adults with epilepsy, however.
Earlier versions of the diet also included a fluid restriction, though this feature fell by the wayside after reports of adverse events due to dehydration (namely constipation and kidney stones).
Most ketogenic diets are marked by an intake of carbohydrates under 20g/day, or rough macronutrient goals of 70% (or more) of calories from fat, 10% (or less) from carbohydrate and 15 – 20% from protein.
This translates to liberal intakes of meats, eggs, butter, oils, cream, nuts and seeds, and very restricted intakes of grains, starchy vegetables, beans/legumes, fruits and added sugars.
Think repurposed “Atkins Diet”, but more restricted (though the ketogenic diet technically preceded Atkins by several decades). This has become particularly popular among those pursuing weight loss, as well as with athletes seeking performance gains and changes in body composition.
Part of the attraction here lies within the simplistic guidelines….it is easy for followers to understand. The diet promises rapid weight loss and blood sugar stability, which in part is an accurate claim.
Any time we restrict large groups of readily available foods, we have potential for weight loss. When one loses weight rapidly, much of that initial weight loss is accounted for by fluid weight and muscle catabolism (breakdown). Further, rapid weight loss can be taxing on the gallbladder and heart, and we run the risk of suffering from nutrient deficiencies as a result of inadequate intake.
This is especially true given that many of the processed/refined foods are easy to access, and just as easy to passively over consume.
Elimination of these foods, in addition to any weight lost, will also give a person a reprieve from erratic changes in blood sugar and corresponding fluctuations in energy levels, though this differentially affects persons who are struggling with overeating carbohydrates (i.e. blood sugar changes are much less dramatic in persons consuming carbohydrate in appropriate proportions). Simply put, we do not need to go on a diet in order to better manage blood sugar and energy levels.
Athletes are typically hit especially hard by the lack of available energy due to the carbohydrate restriction. Not only does performance and power output suffer, but injury risk increases, as carbohydrates play a vital role in buffering the inflammation and tissue damage that are inflicted by exercise.
What are the downsides?
When used for treatment of pediatric epilepsy, the ketogenic diet is typically prescribed in conjunction with close medical monitoring, and only for a short period of time.
With the diet’s surge in popularity among athletes and weight loss seekers, there’s been a deviation from safety guidelines and medical monitoring, and followers are often in ketotic states for extended periods of time without supervision. Given the risks associated with following such an extreme and limited diet, medical oversight is crucial in order to monitor vital signs, organ function (kidney, liver, gallbladder, etc.) as well as blood levels of vitamins, minerals, electrolytes and immune parameters.
Oh, and we can’t neglect to mention the evidence, which does not favor this, or any other fad diet, in terms of weight loss sustainability (nearly all dieters regain weight within 6 months of embarking on the diet).
Suggested macronutrient distributions for healthy persons are as follows. Roughly:
- 50-60% calories from carbohydrate
- 25-30% fat and 10-20% protein.
This may look like a typical dinner meal for many people: 4oz salmon, ¾ to 1 cup of brown rice and 1 cup of colorful veggies with liberal olive oil. Due to the severe restriction of carbohydrate on this diet, we face a number of concerns around vitamin, mineral and electrolyte deficiencies (and the corresponding deficiency symptoms, such as fatigue, depressed immune function, chest pain, nausea and confusion, to name a few).
In situations where ketogenic diets are adequately supervised, followers are prescribed supplements on a daily basis. However, this becomes a bit of a guessing game in our typical ambulatory population, and the tendency is to either overdo supplementation or neglect supplements altogether. Read more about supplements in our post “Tips on Becoming an Armed and Informed Consumer of Dietary Supplements”.
Other important concerns include risk of hyperlipidemia (the diet can raise ‘bad’ cholesterol while diminishing ‘good’ cholesterol levels). Often, there is little attention given to the types or quality of fats consumed while on low carbohydrate diets, which exacerbates hyperlipidemia.
In children or adolescents who are actively growing, ketogenic diets have been shown to stunt growth, which is thought to be due to the fact that the diet can result in a reduction of growth factors and hormones.
Kidney stones, acidosis, loss of bone density, sluggish bowels/constipation (even with adequate fluids and fiber intake), reflux (due to high fat content) and nausea are other relatively common risks with a ketogenic diet.
In closing, there are safer and more sustainable strategies for increasing energy levels and stabilizing blood sugar. Not waiting too long to eat (eating every 3-4 hours), maintaining a diverse diet, comprised largely of whole foods with few, recognizable ingredients is a wonderful (and sustainable) place to start. However, if you are planning on adopting a ketogenic diet, please make sure you do so under the care of a registered dietitian and physician.
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