By Phoebe Chi, MD, MPH
Recently, there has been a lot of talk about the ketogenic diet. Is it safe? Would I recommend it? Despite the recent trend, a “ketogenic diet” is actually not new at all. In the 1970’s, Dr. Atkins popularized his low-carbohydrate diet for weight loss that began with a very strict two-week ketogenic phase. Over the years, other popular diets also incorporated similar approaches for weight loss. But in medicine, we have been using this method for almost a century to treat some forms of epilepsy, especially drug-resistant types in children.
As you know, whenever something is popularized, much information goes around—some accurate, some not so accurate. The purpose of this post is to summarize for you what the medical community actually knows so far through its research on the health effects of ketogenic diets. This post is not to make a stance either for or against, because as you will see, there are both pros and potential cons (as well as some unknowns); rather, I simply want to equip you with the right information in order to empower you to make the best decision for your personal situation.
So let’s get started!
– I –
The Biology in a Nutshell
Definition of a ketogenic diet:
A diet that causes the body to release ketones into the bloodstream.
The physiology behind it:
♦ In your body, most of your cells, by default, prefer to metabolize (break down) blood glucose (sugar) for its source of energy.
♦ This glucose in your bloodstream comes directly from the carbohydrates you eat (therefore by default, carbohydrates are the body’s main source of energy.
♦ In the absence of circulating blood glucose from food, your body starts breaking down stored fat into molecules called ketone bodies (this process is called ketosis).
♦ Once you reach ketosis, most of the cells in your body will start using ketone bodies to generate energy…that is, until you start eating carbohydrates again.
♦ This shift from using circulating glucose to breaking down stored fat as a source of energy usually happens over two to four days of eating fewer than 20 to 50 grams of carbohydrates per day (but this is a highly individualized process, and some people need a more restricted diet to start producing enough ketones).
– II –
The Diet in a Nutshell
♦ Very low carbohydrates, very rich in fats, also relatively heavy on proteins.
♦ The diet typically includes plenty of meats, eggs, cheeses, fish, nuts, butter, oils, seeds, and fibrous vegetables.
♦ The typical macronutrient (“macros”) breakdown (% of calories eaten per day):
70-80% from fat
15-20% from protein
5-10% from carbs.
– III –
The Research in a Nutshell
♦ What we know so far comes from research studies.
♦ These studies are on both humans and animals (rodents). With animal studies, they are able to be more controlled with the diet.
♦ Currently, there are not very many good quality long-term studies.
♦ The studies look at measures that determine the risk of developing (or progressing) diabetes, heart disease, and overall health. These include:
- Blood glucose level
- HbA1c (average of blood glucose over 3 months)
- Insulin resistance (a problem that leads to diabetes)
- Glucose intolerance (a problem that leads to diabetes)
- Total cholesterol (lower is better)
- LDL (bad cholesterol – lower is better)
- HDL (good cholesterol – higher is better)
- Triglycerides (blood fat – lower is better)
- Weight and fat mass
- Blood pressure (lower is better)
- Liver fat content (less or none is better)
– IV –
The Health Effects in a Nutshell
♦ The ketogenic diet is associated with weight loss and improvements in blood pressure, cholesterol, blood glucose, HbA1c, as well as a decreased need for diabetes medication (in those already taking them).
♦ In animal studies, some adverse findings were observed, such as fatty liver disease and insulin resistance.
– V –
The science shows that the ketogenic diet is associated with improvements in many cardiovascular risk factors, such as obesity, type 2 diabetes, and cholesterol levels—especially in the short term. As ketogenic diets are often rich in fats, there remains some potential for longer term problems, such as fatty liver disease and insulin resistance–but the evidence here is still not perfectly clear.
For those who are overweight or obese, there is little doubt that weight loss is beneficial for overall health, and the ketogenic diet has definitely been shown to help with weight loss—especially in the beginning. However, one of the important things with weight loss is that it needs to be sustained long-term to be truly beneficial for the health. It is here that there needs to be more research before it can be considered conclusive.
So is the ketogenic diet right for you? It just might be. But for those who decide it is not, I still recommend sticking to a balanced diet that consists of unprocessed foods and that is rich in colorful fruits and vegetables, lean meats, fish, whole grains, nuts, seeds, olive oil, and a lot of water.
Regardless of whether you are already on it or wanting to give it a try, now you have a bit more information on what the actual evidence shows…and what it does not.
So here’s to eating for health!
Azar, S. T., Beydoun, H. M., & Albadri, M. R. (2016). Benefits of ketogenic diet for management of type two diabetes: a review. J Obes Eat Disord, 2(2). Click for article pdf.
Kosinski, C., & Jornayvaz, F. R. (2017). Effects of ketogenic diets on cardiovascular risk factors: evidence from animal and human studies. Nutrients, 9(5), 517. http://www.mdpi.com/2072-6643/9/5/517/htm