The ketogenic diet has surged in popularity in recent years, becoming the most Googled diet in the United States in 2020, with 25.4 million unique searches. This increased consumer interest has fueled the growth of the "keto" food industry, valuing the global ketogenic diet market at $9.57 billion in 2019. The diet has been widely discussed in popular culture by celebrities, health magazines, and documentaries, making it a trendy option for patients seeking weight loss. However, while there is evidence of benefit, especially regarding weight loss, it’s important to consider the risks and concerns associated with this eating pattern.
History and Evolution of the Ketogenic Diet
The ketogenic diet's origins can be traced back to 1911 when the first modern use of starvation for treating epilepsy was noted. Two physicians in Paris observed that seizures were less severe during periods of starvation. In 1921, Dr. Rollin Woodyatt discovered that acetone and beta-hydroxybutyric acid appeared under starvation conditions. He also found that these compounds were present when patients consumed a low-carbohydrate diet.
In the 1970s, Dr. Robert Atkins introduced nutritional ketosis as a weight loss concept. His 1972 book described how reducing carbohydrates "creates a unique chemical situation in the body…ketones are excreted, and hunger disappears." Since then, many other low-carb diets, such as the South Beach Diet and variations of the Paleo and Mediterranean diets, have gained popularity, remaining a mainstream option for weight loss.
Understanding the Ketogenic Diet
The ketogenic diet is characterized by very low carbohydrate intake with varying levels of protein and fat. The classic ketogenic diet consists of one gram of protein per kilogram of body weight, 10-15 grams of carbohydrates per day, and the remaining calories from fat. The main goal is to induce ketosis, a metabolic state where the body primarily uses fat for energy instead of carbohydrates.
Under ordinary circumstances, the body relies on carbohydrates for energy production, with insulin facilitating the extraction and storage of energy from glucose. When carbohydrate availability is reduced, insulin secretion decreases. Initially, the body uses stored glucose in the form of glycogen, but after three to four days, this is depleted. Stored fat becomes the most readily available fuel, and its breakdown into free fatty acids provides the raw materials for ketone production in the liver.
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Mechanisms Behind Weight Loss
The ketogenic diet has proven to be an effective weight loss therapy, although the exact mechanisms remain unclear. One theory suggests that low-carbohydrate diets decrease insulin fluxes, leading to an increased rate of lipolysis (fat breakdown). This is supported by studies showing that decreased insulin levels in low-carb diets cause increased fat breakdown.
Another proposed mechanism involves increased gluconeogenesis, where the body produces glucose for the brain due to decreased carbohydrate intake. Gluconeogenesis is a metabolically expensive process, theoretically leading to increased energy expenditure. Additionally, the ketogenic diet may directly suppress appetite. Studies have shown that participants on ketogenic diets report significantly decreased hunger, suggesting that ketosis itself may have appetite-suppressing effects.
However, it is important to note that weight loss from the ketogenic diet can be partially attributed to water loss. Studies following obese subjects on a ketogenic diet have shown that initial weight loss includes a significant amount of water.
Efficacy of the Keto Diet: Studies and Meta-Analyses
Numerous studies have evaluated the keto diet’s weight loss efficacy. A meta-analysis by Mansoor et al., which included 11 randomized controlled trials with 1,369 participants, found that participants on low-carbohydrate diets lost 2.17 kg more than those on low-fat diets over six months. However, longer-term studies show less significant weight loss differences.
For example, a meta-analysis by Bueno et al. analyzed 13 randomized controlled trials with 1,415 subjects followed for at least 12 months, comparing very-low-carbohydrate ketogenic diets to low-fat diets. A retrospective analysis of 89 subjects who followed a diet plan cycling between ketogenic Mediterranean and traditional Mediterranean diets showed substantial weight loss for a majority (88.25%) of subjects. This approach may be more feasible for some patients.
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Ketogenic Diet and Diabetes
Before the advent of insulin, low-carbohydrate diets were a mainstay in type 1 diabetes treatment. More recently, there has been significant interest in using ketogenic diets to treat type 2 diabetes in conjunction with obesity. Several proposed mechanisms support the use of ketogenic diets to improve hyperglycemia.
One small study with 28 participants found improvements in glycemic control after 16 weeks of following a ketogenic diet. A two-year, open-label study with 349 participants showed that those following ketogenic diets had a 0.9% decrease in HbA1c compared to a 0.4% increase in the standard care group. Additionally, the ketogenic diet group decreased their use of diabetic medications by 81%. However, another similar trial showed no significant difference in HbA1c levels between low-fat and low-carbohydrate groups after two years.
It is important to understand the impact of the ketogenic diet on patients with type 1 diabetes. While not extensively studied, some trials have shown positive outcomes. However, the hypoglycemic risk of the ketogenic diet in the type 1 diabetes population is a critical consideration.
Cardiovascular Risk Factors
A common concern with the ketogenic diet is its effect on blood lipids and lipoproteins, and its broader impact on cardiovascular disease risk factors. The meta-analysis by Mansoor et al. evaluated cardiovascular risk factors in addition to weight loss, finding variable results.
Another meta-analysis reviewed eight randomized controlled trials lasting six months with 1,633 participants, finding no significant difference in LDL-cholesterol levels between groups. Further analysis suggests that diet composition may significantly affect lipid changes. The increase in LDL-cholesterol seen in some studies may be due to increased intake of saturated fats when carbohydrates are lowered.
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A meta-analysis of randomized controlled trials analyzing long-term effects of low-fat versus high-fat diets included 32 studies with 8,862 participants followed for a minimum of 12 months. In summary, there are enough randomized controlled studies showing increased LDL-cholesterol in the ketogenic diet to warrant caution in certain patient populations. Diet composition likely plays an important role in the lipid changes seen in patients adhering to a ketogenic diet, suggesting that a high-quality diet with adequate intake of fruits and vegetables and low intake of saturated fats would be preferable.
Risks and Considerations
Birth Defects
Evidence suggests that women who become pregnant on low-carbohydrate diets have an increased risk of birth defects. The National Birth Defects Prevention Study found that women with restricted carbohydrate intake were 30% more likely to have infants with neural tube defects and decreased folic acid levels. Women planning to become pregnant should avoid restrictive low-carbohydrate diets.
General Concerns
Although ketogenic diets are popular, their use must be approached with caution. While there is data showing impressive short-term weight loss, most analyses suggest that long-term efficacy is comparable to other hypocaloric diets. This may be due to the difficulty of long-term adherence to such a restrictive eating pattern. Additionally, some weight loss during the acute period may be related to water loss rather than true fat loss.
For patients with type 2 diabetes, any weight loss achieved with the ketogenic diet could lower A1c and help reduce medication burden. However, long-term safety and health have yet to be proven, especially regarding lipid profile alterations and cardiovascular impact. Studies generally show improvement in HDL and triglycerides, but LDL response is variable, possibly due to significant variability in individual diet content.
Potential Side Effects
Following a very high-fat diet may be challenging to maintain, and some negative side effects of a long-term ketogenic diet have been suggested, including increased risk of kidney stones and osteoporosis, and increased blood levels of uric acid (a risk factor for gout). Possible nutrient deficiencies may arise if a variety of recommended foods on the ketogenic diet are not included.
It is important to not solely focus on eating high-fat foods, but to include a daily variety of the allowed meats, fish, vegetables, fruits, nuts, and seeds to ensure adequate intakes of fiber, B vitamins, and minerals (iron, magnesium, zinc)-nutrients typically found in foods like whole grains that are restricted from the diet.
Psychological Impact
Micromanaging food intake by tracking how much you eat can disconnect you from what your body is asking for. You start using outside numbers to determine what to eat instead of listening to your body. Being intuitive and understanding what your body needs is essential for proper nourishment. Monitoring food so closely can lead to psychological distress, such as shame and binge eating.
Other Risks
The keto diet can cause your blood pressure to drop in the short term due to a reduction in blood volume and changes in your fluid balance. Symptoms of low blood pressure include dizziness, lightheadedness or fainting, especially when standing up quickly. Following a keto diet can also cause your blood sugar to drop, which can be dangerous for people living with diabetes. Common symptoms of low blood sugar include weakness or shaking, sweating, a fast heartbeat and dizziness.
Criticisms and Negative Reviews of "Your Keto Diet"
Many users have reported negative experiences with "Your Keto Diet," citing issues such as unexpected charges, difficulty canceling subscriptions, and dissatisfaction with the meal plans. Several reviewers have labeled the service as a "scam," reporting unauthorized charges and a lack of customer service.
Some users have complained about the lack of transparency in the app, with no way to check subscription status or renewal date. Others have criticized the meal plans as being generic and not tailored to individual needs, with one reviewer claiming the plans were created by AI.
Alternatives and Sustainable Approaches
For long-term weight loss, healthcare professionals advocate making small, consistent changes based on individual health goals. Intermittent fasting is an alternative approach that allows you to receive the benefits of ketosis while still eating a varied and balanced diet. By cycling between periods of eating and fasting, your body enters “mild ketosis” during the fasting phase. Unlike the keto diet, which requires strict food restrictions, intermittent fasting lets you enjoy a variety of nutrient-dense foods, such as fruits, vegetables, whole grains and legumes, during eating windows.