Every January, we’re bombarded with messages that a new diet or gym membership is the key to a “new us” in the new year. As the calendar flips, our mindset often follows suit, and many of us look to shave off a few holiday pounds with a diet that provides quick results. One diet that gets a lot of attention for this is the ketogenic diet, an eating style that has grown in popularity in the last decade.
You may have heard of the ketogenic diet (often called by its shorthand, “keto”) but you may not actually know much about it. This article explains the basics of the ketogenic diet, with a few cautionary tips you should know if you are thinking about giving it a go.
What is the ketogenic diet?
Although it may seem like the ketogenic diet has been recently created, it’s not a newly discovered way of eating. In fact, the ketogenic diet was first put into practice in the 1920s as a treatment for people with epilepsy after research demonstrated that fasting reduced seizure activity. Therapeutic usage of ketogenic eating patterns by medical professionals continues today, but the diet is also becoming more popular outside its clinical applications.
What exactly is the ketogenic diet? The ketogenic diet is an eating pattern that includes high amounts of fat, low to moderate amounts of protein, and very little carbohydrates. The keto diet is typically rich in foods like butter, cheese, eggs, meat, nuts, oils, seafood, and seeds. It does not allow much, if any, room for fruits, vegetables, grains, potatoes, sweets, or other carbohydrate-rich foods.
Although there are variations to the ketogenic diet, they all share a primary objective of restricting carbohydrate intake. A typical ketogenic eating plan aims for about five percent of calories from carbohydrates, 20 percent from protein, and 75 percent from dietary fats. On a 2,000-calorie-per-day ketogenic diet, this equates to about 100 calories (25 grams) of carbohydrates, 400 calories (100 grams) of protein, and 1,500 calories (167 grams) of dietary fat. Although some ketogenic diets, depending on their phase and the calorie needs of the eater, can accommodate up to 70 grams of carbohydrates per day, 50 grams or less is a typical maximum intake goal.
By restricting carbohydrates and monitoring protein intake, a ketogenic diet aims to put your body in a state of nutritional ketosis, a metabolic process that increases the production of ketones, which are made by the liver and can be used as the body’s primary energy source. When we are not in ketosis, glucose (derived from carbohydrate intake) is our body’s primary energy source.
Ketones are water-soluble byproducts of the breakdown of fat in the liver. The production of ketones is a normal bodily process that occurs regularly, including while we sleep. Our liver is always producing some ketones—but when our daily carbohydrate and protein consumption are high enough, our ketone production remains relatively low.
How do dietary carbohydrates provide energy?
There are two kinds of carbohydrates—kinds that we can digest, and dietary fiber, which we cannot digest. When we consume digestible carbohydrates, our bodies break them down into their simplest forms: the monosaccharides fructose, galactose, and glucose. Most of the carbohydrates that we consume eventually end up as glucose, because glucose is the most common monosaccharide found in nature, and our bodies can convert fructose and galactose into glucose.
Glucose is critical to our survival. A constant supply of glucose is routed to circulate in our bloodstream, which, with the assistance of insulin, ensures energy is readily available. Glucose reserves are also stored in the liver and muscles as glycogen. We typically have about a day’s worth of glucose locked up as glycogen. When blood glucose is low, the liver breaks down glycogen to raise blood glucose. When we need energy for muscular contraction and our blood glucose is low, our muscles break down their glycogen reserves.
How do we get energy without dietary carbohydrates?
Whether we’re eating, exercising, sitting, or sleeping, our bodies are busy monitoring and securing our energy supply. And, when necessary, our bodies generate the energy they need from non-carbohydrate sources.
One way our bodies do this is through gluconeogenesis, a process that uses non-carbohydrate substances to generate glucose. We can also utilize protein and fat for energy. For example, amino acids in the proteins we consume can be used during gluconeogenesis to make glucose. And triglycerides—a type of fat that we store in adipose tissue—can be broken down through lipolysis and used to start a sequence of events that generates ketones when our glycogen stores are gone.
In short, relying less on carbohydrates for energy increases ketone production. Although the liver is always producing some ketones for energy from fat, the more the body shifts to fat as an energy source, the more its ketone production ramps up. But eating too much protein can reduce ketone production, thus making it more difficult to reach and maintain ketosis, which is why a true ketogenic diet has limits on protein intake as well as carbohydrate intake.
Important Things To Know About Keto
With a better understanding of what a ketogenic diet is and how it works, let’s tackle a few of its pros and cons.
Keto can kickstart weight loss.
Perhaps the biggest attraction to adopting a ketogenic diet is the promise of weight loss. And many people do experience rapid initial weight loss from following a ketogenic diet, mainly due to reduced calorie intake, which may result from influences associated with low carbohydrate intake such as increased fullness and decreased hunger and appetite. Loss of body water and increased energy expenditure (i.e., more calories burned) are also believed to play a role. When you quit keto, however, some immediate regain of body weight will occur as the body rebuilds its glycogen stores, a process that retains water (and its associated weight).
Many types of diets can help people lose weight in the short term. But keeping the weight off is the hard part. Weight loss and other health benefits associated with specialized diets tend to fade after about a year. But some research has shown that the two-year threshold may be an important milestone to reach for successful long-term weight maintenance. These are unfortunate realities whether one follows a low-carb/high-fat diet such as keto or any other lower-fat/higher-carb pattern of eating.
Sticking with any diet for the long-haul is hard—even keto.
Maintaining weight loss is challenging no matter what type of diet you follow, partly because sticking to a specialized diet for long periods of time is difficult. Recent research showed that adherence to a well-formulated ketogenic diet was similar to that for the Mediterranean diet during the 12-week crossover study, but that adherence to keto was lower during the 12-week period that immediately followed the 24-week intervention. A separate two-year study comparing adherence to low-carb, low-fat, and Mediterranean diets showed higher adherence to a low-carb diet during the first six months, but lower compliance overall and more drop-outs among the low-carb group by the end of the study.
Keto may help with some health conditions, but not others.
The volume of research on the impact of a ketogenic diet on specific diseases, especially diabetes and obesity, is growing. In addition to its original use to treat epilepsy, more recent research has demonstrated improvements in weight loss and insulin and blood-glucose markers in the early stages a ketogenic diet, although these advantages disappear after about a year and depend on what type of diet is compared to a ketogenic diet. Similar benefits for insulin and blood-glucose markers have been shown from non-ketogenic diets when polyunsaturated fats replace carbohydrates or saturated fat. Ketogenic diets are also known to raise LDL-cholesterol in some people. LDL is the “bad” kind of cholesterol that we want to keep low to support heart health.
The health effects of a ketogenic diet on specific health conditions is an area to keep an eye on. If you are considering a ketogenic diet to address a chronic health condition, please consult a registered dietitian or your primary healthcare provider to ensure that you do it safely.
Keto does not align with the Dietary Guidelines for Americans.
With its emphasis on carbohydrate restriction, lack of a limit on saturated fat, and no fiber intake goal, a ketogenic diet is at odds—at least in these three compartments—with advice in the Dietary Guidelines for Americans (DGA).
Keto may or may not be an improvement from your current diet.
Unfortunately, very few Americans eat like the DGA recommend, and there is clearly room for improvement in the typical American diet. Depending on your own eating habits, adopting a ketogenic diet may or may not get you closer to DGA recommendations. A well-formulated ketogenic diet that emphasizes lean proteins and dairy, as well as plant foods such as berries, non-starchy vegetables, nuts, and seeds, can benefit your health—especially if you don’t already consume such foods or if you typically overconsume added sugar, calories or sodium.
Keto cuts food groups.
A ketogenic diet severely restricts all forms of carbohydrates. This means that entire food groups such as dairy, fruits, grains, and vegetables must be limited or possibly avoided completely. While cutting carbs is the driving force to achieve and maintain ketosis, carbohydrate-rich foods such as dairy, fruits, vegetables, and whole grains are integral to a wide-range of eating patterns that are proven to benefit health. A well-formulated ketogenic diet, however, may include limited amounts of certain fruits such as berries, as well as non-starchy vegetables such as broccoli.
Keto keeps it simple.
Restrict carbs, then reach and maintain ketosis. Given the simplicity of keto’s advice to veto carbohydrates, it’s easy to see why people give it a try. But nothing is ever as simple as it seems. If you’re looking for a more balanced keto approach, look into a well-formulated ketogenic diet in conversation with a registered dietitian (or your doctor).
You’ll feel blue with the “keto flu.”
The rumors you may have heard are true. During the first weeks of a ketogenic diet, people often report feeling different than they normally do—and not in a good way. Commonly reported symptoms include constipation, fatigue, headaches, lightheadedness, and an upset stomach. Thus, the “entry phase” of starting a ketogenic diet has been deemed the “keto flu.” Staying well-hydrated and adding a little extra salt to your food can help alleviate some of these symptoms. The good news is that this phase is temporary, and once you’ve adapted, these symptoms should disappear.
Beware of bad breath.
Just like the “keto flu,” this unfortunate aspect of a keto diet can also be true. “Keto breath” results from the body’s production and exhalation of acetone, a type of ketone that is less critical for energy during ketosis. Keto breath is not the same as regular bad breath, so improving your dental hygiene, while always a good idea, won’t cure this side effect of ketosis. But fear not: The condition is only temporary, and its intensity varies from person to person. And you’ll likely notice an improvement in your breath as soon as your body adapts to its new primary fuel source.
Food restrictions can alter our relationship with food.
Going keto is a big change for most people. And big dietary changes can affect the way we look at food and our relationship with it. Simplifying food choices through restriction might not be helpful for everyone, so it’s important to be mindful of how our relationships with food evolve as we alter our eating patterns. Perhaps most importantly, when we develop a purely transactional relationship with food—one that views it only as a means to an end—we may fail to respect the joy, satisfaction, and traditions that foods can offer. Special care should be taken when following a restrictive diet, particularly for those with a history of disordered eating.
Keto: A Conclusion
A ketogenic diet can be a healthier and simpler way of eating for some people. For others, it may not be. Due to its therapeutic origins, a ketogenic diet may be too restrictive and have too many barriers for the average person to begin and/or maintain, and its clinical benefits may not apply to you. The ketogenic diet does not align with the Dietary Guidelines for Americans, especially their recommendations for carbohydrate and saturated fat intake. At the same time, much research has been conducted on ketogenic diets, many studies are currently underway, and more will surely be pursued in the decades ahead. As more people contemplate giving keto a go, it will be critical for researchers to better understand the advantages and disadvantages of this eating pattern beyond its clinical research settings.