Ketogenic Diets: The science behind the hype

Hover to see what my clients are saying >



What is a ketogenic diet?



A ketogenic diet is a low-carb diet with a goal of increasing the amount of energy your body gets from fat. To understand how this process occurs, you'll benefit from a mini-biology lesson.


Your body gets energy from the foods you consume or consumed in the past and stored. When you eat a sugary food, like a highly processed breakfast cereal, your body quickly turns that food into glucose. Glucose is a simple sugar that your body uses for energy production.


With enough glucose in your blood, your body (specifically your pancreas) increases insulin production. Insulin tells your body to avoid converting fat into energy and instead tells it to use energy from carbohydrate sources, the glucose that's been stored. Because we have excess glucose than we need at the moment, your body converts it into a form that's easier to store called glycogen.


As an analogy, you can think of glucose like the cash you have on-hand and glycogen like a debit card. You probably wouldn't want to have all of your cash in your pocket, so you store it in a bank account. When you're in a situation where you need more money than what's in your wallet, you can reach for your debit card and still be able to make the purchase. This is conceptually similar to how your body uses energy, it will use what's easily available first and then reach for what's been stored.



The glycemic index and insulin production



Typical diets in the United States include foods with a high value on the glycemic index. The glycemic index measures how quickly your body turns food into glucose in your blood. When you consume high-glycemic index foods, your body gains a lot of glucose in a short time, insulin production spikes, and you stop burning fat for energy.

When you purposefully reduce the amount of carbohydrates in your diet, your body won't produce as much insulin. Since higher insulin levels indicate more energy should come from glycogen, lower insulin levels indicate that the body should increase the amount of energy that comes from its fat stores.

Your liver converts fat into an energy source called ketones. When this happens, your body is in a state called ketosis, meaning more energy is coming from ketones rather than glycogen. Put differently, you're burning more fat than you normally would.



Why do people go on a ketogenic diet?



Based on the change in energy sources, a major reason people go on ketogenic diets is to trigger weight loss. As a word of caution, you'll likely lose fat when pursuing a low-carb diet. The weight loss may be temporary if you switch back to a high-carb diet after you've reached your goal weight. So, rather than going on a ketogenic diet, losing weight, and switching back to a high-carb diet, you may want to reduce your consumption of carbohydrates so you can gain the best of both worlds.

Another reason someone would pursue a ketogenic diet is to help regulate other conditions like epilepsy or diabetes. When you have an underlying condition or are susceptible to developing a chronic medical condition, you must be even more cautious about changes to your diet. The food and drinks you consume are a major contributor to your health and pursuing a diet for short-term benefits can contribute to long-term problems.



Are there downsides to the ketogenic diet?



A big downside to ketogenic diet is its strict nature. To maintain ketosis, you'll need to drastically reduce the amount of carbohydrates in your diet (usually to less than 50 grams per day). Since the Western diet contains so many high-carb foods, you may be surprised at how easy it is to miss this goal. A single, 20 ounce bottle of soda typically provides more carbs than you're supposed to consume on a ketogenic diet. If your diet currently contains a high amount of carbs, then you may have trouble maintaining the ketogenic diet long enough to reach a weight loss goal.

When you switch to a ketogenic diet, you may experience withdrawal-like symptoms known as the keto flu. This occurs because you're changing how your body produces energy. Keto flu usually occurs within a few days after you drastically reduce your carbohydrate intake and subsides a week later. You can reduce the intensity of keto flu by following other healthy habits like staying hydrated and getting plenty of sleep.


A more subtle downside can happen when you are meeting the ketogenic diet, but you're not necessarily eating a healthy diet. It might not help you reach your long-term goals if you replace unhealthy foods with other unhealthy foods. Commonly those who choose to go on a ketogenic diet may increase the amount of foods that are highly processed. This might lead to a diet that's less healthy than what you were consuming before.



Should I go on a ketogenic diet?



Before jumping into a new diet, you should evaluate your goals, your long-term plans, and your current health situation. Nutritional counseling can help you understand which changes may give you the greatest benefit for the lowest effort. For example, if your current diet consists of many less-than-healthy foods, then you may benefit from limiting those sources prior to the more drastic changes that come with a ketogenic diet.


Taking little steps that move you forward on your health journey might be easier and since they're easier, you may be more likely to maintain those new habits. It's far better to improve slowly and regularly than to oscillate between a strict diet and a poor diet.

Lastly, like any change to your lifestyle, you should understand your health history. If you have underlying conditions a diet change could make them worse. On the other hand, if you're already healthy, then diet changes may not make you happier or healthier, so take care to do your research and consult with medical professionals to make the best choice.