The keto diet has become extremely popular. It’s been praised mainly as a weight management tool, but other additional benefits to health and everyday function have been claimed.
While it might seem to be fresh and trendy, the keto diet is nothing new. It was first introduced in the 1920s as a treatment for epilepsy, which is a neurological disorder the causes seizures (1). As anti-epileptic drug treatment evolved, the therapeutic use of the diet declined.
However, over the past fifteen years, the keto diet has evolved to become a mainstream tool for fat loss, blood sugar control, and more. In this article, we’ll break down the science behind ketosis, what the keto diet actually is, and discuss the pros and cons.
What is ketosis?
When your body is functioning normally and you consume a regular diet, carbohydrates are broken down into glucose and used as the main fuel source for energy. However, when carbohydrates are limited, your body turns to other sources of energy. Ketosis occurs when you start burning fat to make products called ketones, which are used for energy by the brain. Since protein is needed to maintain muscles and tissues, it is only used if dietary fat is also not sufficient to meet your needs.
It’s important to note that ketosis is different from ketoacidosis. Ketoacidosis is when blood sugar rises to a dangerously high level. This leads to the blood becoming acidic, which is harmful. Ketoacidosis usually occurs in people with type 1 diabetes, although it may also occur in those with type 2 diabetes and with severe alcohol abuse.
What is the keto diet?
The keto diet is the intentional restriction of carbohydrates where the goal is to put the body into ketosis. The exact carbohydrate limit varies from person to person; it’s typically maxed at 50 grams per day, although it can be as low as 20 grams per day (2). In general, the remaining 70-80% of the diet comes from fat, and 10-20% comes from protein.
In order to stick to this low carbohydrate ceiling, followers of the diet avoid eating starches. That includes foods such as bread, cereal, pasta, rice, grains, potatoes, and corn. People on the diet generally avoid other foods that are high in carbohydrates, like fruit. Even foods that one might not think of – such as beans, avocados, and dairy – must be limited since they can contribute carbohydrates as well.
Due to the diet being high in fat, the plan allows for plenty of foods like nuts, seeds, and plant oils. The keto diet also enables its fans to eat plenty of proteins like meat, poultry, seafood, and eggs. Most keto diet plans allow for less healthful sources of fat and protein, such as bacon and butter. Some plans encourage followers to eat plenty of non-starchy vegetables, such as leafy greens, cruciferous vegetables, tomatoes, cucumbers, and more.
What are the pros of the keto diet?
The biggest lure of the keto diet is its promise to help you lose weight. There are plenty of studies to suggest that it can help its followers to shed body weight (3). However, there is also research to suggest that it might be just as effective as a low-fat diet when it comes to weight loss (4).
Recall that the only way to lose weight is to be in a calorie deficit, and that still holds true even with ketosis. However, there are some theories to suggest that the keto diet might have added weight loss abilities related to the following:
- Fat and protein are very satiating, which reduces appetite and makes it easier to eat less without feeling hungry or deprived.
- Higher protein intake might help promote weight loss due to the increased thermogenic effect of food and ability to suppress ghrelin, the “hunger hormone.”
- Converting fat and protein into ketones requires extra energy, thereby increasing the amount of calories burned at rest (metabolic rate).
Another major allure of keto is its potential ability to help stabilize blood sugar and improve insulin response. This possible benefit may be related to weight loss. However, it could also have to do with the low-carbohydrate nature of the diet. For example, one study found that low-carbohydrate diets can improve insulin sensitivity by 75% (5).
In addition to its original use as a therapy for epilepsy, studies have shown keto to benefit a variety of conditions. This includes: heart disease, cancer, Alzheimer’s disease, Parkinson’s disease, and more. However, further research is necessary to conclude whether or not keto can truly improve these conditions.
Moreover, an interesting potential advantage of the keto diet is its effect on cognition, sleep and mood. There have been many anecdotal reports that ketosis promotes mental clarity, improved sleep and regulated mood. However, a randomized controlled trial found that three weeks on the diet unfortunately did not have this positive effect (6).
What are the cons of the keto diet?
The most obvious and influential disadvantage of following the keto diet is the strict requirements around carbohydrates. Many people find that the diet is too restrictive to sustain long-term. Some might feel deprived of their favorite foods. It might also interfere with social life. Moreover, this restriction might lead to overeating or bingeing down the road, derailing any weight loss efforts.
Another downside to the keto diet is a side effect known as “keto flu.” Some people report experiencing gastrointestinal distress for the first few days when in ketosis (7). Some common symptoms include diarrhea, constipation, and vomiting. Less common side effects include lack of energy, increased hunger, trouble sleeping, nausea, and reduced exercise capacity. Some people suggest eating into ketosis to minimize side effects by gradually reducing carbohydrate intake. Adding liberal salt to meals might also help promote normal electrolyte balance.
Furthermore, the effect of the keto diet on the microbiome has been under review. Some researchers have speculated that restricting carbohydrate intake might lead to unfavorable shifts in the diversity and robustness of the beneficial bacteria living in the gut (8). While this area of interest still remains inconclusive, it is a factor to consider when deciding to eliminate carbohydrates. Specifically, carbohydrates that are rich in fiber and phytonutrients should be prioritized.
The bottom line
The keto diet is simply an extremely low-carbohydrate diet. Restricting carbohydrate intake to below a certain threshold forces the body to burn fat for energy. The diet might promote weight loss, aids in blood sugar response, benefits certain health conditions, and has neurological advantages. However, it could be unsustainable for many people, come with negative side effects, and possibly impair gut health.
