Ketogenic Diet Definition
Is a ketogenic diet a miracle cure for obesity? Diabetes? Epilepsy?
Some people say so. And while it certainly can help some people with some health concerns, it’s considered a “medical diet” that can be risky for some people.
The ketogenic diet seems to be buzzing in the “healthosphere” lately, but in fact, it was first documented almost 100 years ago.
How do you know if it’s best for you? As a nutrition professional, let me help you better understand what it’s all about and some of the things to consider before diving into the ketogenic diet.
What is the ketogenic diet?
Unlike popular diets that focus on the amount of protein or carbs you eat, the ketogenic diet focuses on fat. It’s a restrictive diet that is a very low-carbohydrate and high-fat diet.
Yes, a high-fat diet!
While fat had been unfairly treated as the cause of obesity and contributor to heart disease, diabetes, and cancer, new research in both people and animals suggests this is not the case. In fact, the high-fat ketogenic diet has been shown to help some people achieve weight loss pretty quickly (but keep reading before you dive into it). This new knowledge is partly because the health effects of sugars weren’t a big part of the research until recently. Evidence is growing to suggest that the intake of sugar-sweetened foods and drinks is more closely associated with increased risks of obesity and diabetes.
Note that starting a ketogenic diet can result in a loss of up to 10 lbs in two weeks with some of that weight loss due to water loss. Interestingly, the ketogenic diet seems to help dieters keep their lean body muscle, unlike other weight loss diets.
In fact, the idea behind using your diet to affect your metabolism all started in the 1920s. This is when the ketogenic diet was first used as a therapeutic diet to help treat pediatric epilepsy. This continued for about a decade until antiepileptic agents were introduced. The popularity of the ketogenic diet has recently resurfaced, this time as a weight-loss and blood-sugar control diet.
How ketosis works
The idea behind the ketogenic diet is to switch your body’s metabolism to another system. Normally your body uses glucose (a carbohydrate) as its main fuel. Carbohydrates are sugars and starches found in many nutritious foods such as fruits, vegetables, legumes, and whole grains. Glucose is the primary source of energy for your tissues and organs like your brain and muscles. But, because your brain is so important to your survival and humans evolved to live through periods of fasting, you have a “backup” system to make sure your brain can still have the energy to help you survive.
That backup energy source is ketones.
Ketones are biochemicals naturally produced by your liver from fat in times of fasting when food is scarce. Your brain, heart, muscle, and kidneys can use them for fuel when you aren’t eating enough carbohydrates. It’s a survival mechanism that switches your metabolism from a glucose-based system to a ketone-based one. That ketone-based metabolic state is called “nutritional ketosis.”
The difference here is that you use the ketogenic diet to switch your metabolism to ketosis without fasting.
Ketosis from the ketogenic diet is not to be confused with ketoacidosis which is a serious complication where the pH of the blood becomes too acidic.
How to shift into ketosis
In order to encourage your metabolism to shift into ketosis, you need to dramatically cut down on the number of carbohydrates you consume and focus on getting most of your daily calories from fat.
The approximate macronutrient combinations for a ketogenic diet are:
5-10% carbohydrates (up to 50 g per day)
For an average adult who needs 2,000 calories per day, that adds up to only 20-50 calories from carbohydrates per day. To put this into perspective, one medium-sized banana has 27 grams of carbohydrates.
This is much different from the dietary guidelines that recommend:
45-65% carbohydrates (about 130 g per day).
When your body gets under 50 g of carbohydrates per day like when on a ketogenic diet, it uses up its temporary carbohydrate storage (glycogen). Then after a few days, it goes through two metabolic changes. The first one is to make its own glucose (gluconeogenesis) and the second is to make the alternate fuel, ketones. This is how you get into nutritional ketosis and this metabolic state continues as long as you strictly maintain this very low level of carbohydrate intake every day.
The ketogenic diet for obesity, diabetes, and brain health
Some studies show that a well-formulated ketogenic diet can help people who have excess weight, metabolic syndrome, insulin resistance, and type 2 diabetes. This diet helps with blood sugar control because there are fewer carbohydrates in the diet and this also helps with insulin sensitivity. Ketogenic diets may help reduce weight and improve blood pressure, blood sugar regulation, and blood lipids (triglycerides and HDL cholesterol).
As time goes on in nutritional ketosis, hunger subsides and this can result in an overall reduction of caloric intake which further contributes to weight loss
However, the ketogenic diet may increase blood LDL cholesterol, especially if it includes high levels of saturated fats like coconut or palm oils, lard, butter, and cocoa butter.
Because there is limited information on the long-term effects of the ketogenic diet, it is not generally recommended for the prevention of type 2 diabetes or heart disease.
When it comes to brain health, the ketogenic diet has some promise in epilepsy, dementia (Alzheimer’s), ALS (amyotrophic lateral sclerosis), and traumatic brain injury.
Another benefit of the ketogenic diet is that, unlike glucose, ketones act as antioxidants and decrease free radical damage.
Even though this diet can help with short-term weight loss, like most diets, it is usually not sustained over the long run.
Watch out for these side effects of the ketogenic diet
The long-term outcomes of maintaining a metabolic state of ketosis aren’t well-known right now. However, there are some well-documented short-term (< 2 years) side effects to consider.
Some of the common short-term side effects sometimes referred to as the “keto flu,” include:
Difficulty in exercise tolerance
These “keto flu” symptoms usually clear up within a few weeks and can be minimized by ensuring adequate intake of fluids and electrolytes.
There are also side effects such as muscle cramps, bad breath, and loss of energy. This is why some researchers recommend monitoring people on a ketogenic diet for blood glucose, and other parameters.
Some of the long-term side effects include issues with the kidneys (kidney stones) and liver (hepatic steatosis or “fatty liver”), as well as vitamin and mineral deficiencies.
There are additional cautions for those with diabetes and anyone taking medications for blood sugar control. See your doctor about adjusting your medications before starting a ketogenic diet as there is a risk of severe low blood sugar.
The ketogenic diet is not recommended if you have pancreatitis, liver failure, disorders of fat metabolism, carnitine deficiencies, porphyria, or pyruvate kinase deficiency. If you’re on a ketogenic diet, it’s recommended that your kidney function is regularly monitored by your healthcare professional.
It is also possible, but rare, for some people on a ketogenic diet to have a false positive breath alcohol test.
There are many reports of complications of the ketogenic diet that has led people to the hospital for things such as dehydration, electrolyte disturbances, and hypoglycemia (very low blood sugar).
The ketogenic diet can be hard to maintain
As with any significant lifestyle change, sticking with a ketogenic diet can be tough. Sometimes the initial weight loss and blood sugar control is motivating, but often this can become boring. Plus, if you start feeling side effects, this can be frustrating.
Many researchers suggest that the ketogenic diets not be widely recommended until more research is done on their short- and long-term effects on different types of people.
If you’re on it and decide to go back to a standard diet, this transition should be slow and well-controlled.
There isn’t much research on how this diet affects people after they discontinue it, or for those that continue beyond the first two years.
Instead of experimenting on yourself, I highly recommend that you see a health professional before embarking on the ketogenic diet.
Research shows that people who are on a ketogenic diet are at risk for deficiencies in essential vitamins and minerals. This is because many foods packed with vitamins and minerals, like fruits and vegetables, contain carbohydrates and are highly restricted on a ketogenic diet.
Some of the fruits and vegetables “allowed” on the ketogenic diet include small amounts of berries, leafy greens, brassicas (cauliflower, broccoli, Brussels sprouts), asparagus, bell peppers, cucumber, celery, summer squashes, mushrooms, onions, and garlic.
Since the ketogenic diet is based on eating a lot of fat, I recommend choosing healthy sources like olive oil, avocados, nuts, and seeds.
If you are on or thinking about starting a ketogenic diet, consult a certified dietitian who can review your health goals and nutritional status. Need a personalized list of recipes and a meal plan to help you enjoy food and reach your health goals? Here is my link to book a chat about making sure to meet your dietary needs. Book an appointment with me to see if my product/program/service can help you. Click here to schedule your free consultation.
Harvard Health Publishing. (2018, October). Should you try the keto diet? Retrieved from https://www.health.harvard.edu/staying-healthy/should-you-try-the-keto-diet
Harvard Health Publishing. (2019, August). Can the keto diet help me lose weight? Retrieved from https://www.health.harvard.edu/staying-healthy/can-the-keto-diet-help-me-lose-weight
Masood, W. & Uppaluri, K. R. (2019, March 21). Ketogenic Diet. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK499830/
Shilpa, J., & Mohan, V. (2018). Ketogenic diets: Boon or bane?. The Indian journal of medical research, 148(3), 251–253. doi:10.4103/ijmr.IJMR_1666_18
U.S. Department of Health and Human Services and U.S. Department of Agriculture. Office of Disease Prevention and Health Promotion. (2015, December). Dietary Guidelines for Americans 2015-2020, Eighth Edition. Retrieved from