The Surprising Science Behind the Ketogenic Diet and Its Implications for Our Health
For over five decades, dietary guidelines in the United States have preached the importance of reducing saturated and total fat intake. Yet, during this time, obesity and diabetes rates have surged, painting a grim picture for public health and the economy.
Enter the ketogenic diet, a high-fat, very-low-carbohydrate eating plan that has garnered much attention lately. Often dismissed as a passing trend, this diet has a rich history in clinical medicine and human evolution.
More intriguingly, it appears to outshine low-fat diets when it comes to managing obesity and diabetes. But that’s not all; chronic ketosis, a state achieved through this diet, might offer unique metabolic benefits that extend to conditions like cancer and neurodegenerative diseases.
So, what’s the deal with the ketogenic diet, and should you consider it for your health journey?
A Century-Old Diet for Modern Times
Believe it or not, the ketogenic diet was once a standard of care in diabetes management. It helped extend the lives of children with type 1 diabetes and eased the symptoms of type 2 diabetes in adults.
Why? Because at the core of all diabetes forms lies the issue of carbohydrate intolerance, something the ketogenic diet addresses by severely restricting carb intake to less than 50 grams a day, with more than 70% of calories coming from fats.
The discovery of insulin in the 1920s transformed diabetes management, making it possible to control blood sugar levels with high-carbohydrate diets. However, despite the advancements in insulin therapy and drugs for associated conditions like dyslipidemia and hypertension, the human and economic costs of diabetes complications continue to mount.
Surprisingly, the shift toward higher-carbohydrate diets by the U.S. public in the latter half of the 20th century might have contributed to the rise in obesity, a significant risk factor for type 2 diabetes.
Carbohydrate Restriction: A Game-Changer in Obesity Treatment
For decades, dietary fat was painted as the villain responsible for obesity due to its high calorie content and delicious taste. However, recent research points to the metabolic effects of food, rather than calorie content, as the key determinant of long-term body weight.
According to the carbohydrate-insulin model of obesity, processed carbohydrates, such as bread, rice, sugary products, and potatoes, promote fat storage, increase hunger, and reduce energy expenditure. This sets the stage for obesity and diabetes in susceptible individuals.
Many clinical trials comparing diets with varying macronutrient compositions have used low-intensity interventions, leading to insignificant long-term dietary changes. This could explain why meta-analyses of such trials show little difference in long-term weight loss between low-fat and other diets.
However, when it comes to ketogenic diets, anecdotal evidence suggests they can better suppress hunger during weight loss, translating to more effective weight loss overall.
One 1950s study, for instance, found that female college students on a low-fat diet felt hungry and lacked energy throughout the study, while those on a very-low-carbohydrate diet felt satisfied and didn’t struggle with hunger, despite losing more weight.
More recent research further supports the idea that low-carbohydrate diets can reduce hunger and lead to greater weight loss.
The Ketogenic Diet’s Promise in Diabetes Treatment
While the U.S. National Institutes of Health sponsored several large studies on low-fat diets, the results were underwhelming, offering little to no benefit for diabetes prevention or management. However, low-carbohydrate diets, including those aiming for nutritional ketosis, have shown promise.
A 2019 Consensus Report from the American Diabetes Association recognized low-carbohydrate diets as some of the most studied eating patterns for type 2 diabetes. These diets were found to reduce glycated hemoglobin (HbA1c) levels and the need for antihyperglycemic medications.
In a pragmatic trial, adults with type 2 diabetes on a very-low-carbohydrate diet experienced significant weight loss and decreased HbA1c levels, even reducing their reliance on hypoglycemic medications.
While there is limited research on carbohydrate restriction in type 1 diabetes due to concerns about hypoglycemia and ketoacidosis, a survey of individuals following a very-low-carbohydrate diet for type 1 diabetes found exceptional glycemic control, low rates of hypoglycemia and ketoacidosis, and high satisfaction with diabetes management.
Breaking Stereotypes: High Fat and Heart Health
It might sound counterintuitive, but even though a ketogenic diet often contains high levels of saturated fat – a known risk factor for cardiovascular disease (CVD) – it might not be as bad as it seems. While LDL cholesterol, a key CVD risk factor, can rise on low-carbohydrate diets due to the high saturated fat content, other factors, like lipoprotein size distribution, can indicate a relatively lower CVD risk.
Individuals with isolated elevated LDL cholesterol have been found to be at lower risk for coronary events and less responsive to statin treatment. Interestingly, the mechanism triggered by a ketogenic diet resembles that of sodium-glucose cotransporter 2 inhibitors, a drug class used to treat diabetes.
Both shift the body’s energy source from carbohydrates to fats, induce ketosis, lower glycemic excursions, reduce insulin levels, cause weight loss, promote sodium excretion, and decrease blood pressure – actions that might counteract the adverse cardiovascular effects of elevated LDL cholesterol.
Ketosis: A Potential Metabolic Superpower
Ketosis, an ancient metabolic pathway, could hold the key to unique health benefits beyond those associated with high-fat diets. It has been called a “superfuel” for the brain, critical for infants and possibly beneficial for neurodegenerative and neuropsychiatric disorders. Patients with Alzheimer’s disease, characterized by central insulin resistance, have shown clinical improvements with a ketogenic diet or exogenous ketones. Additionally, a ketogenic diet might improve overall mood.
In the realm of oncology, ketosis might provide an innovative approach. Many cancers rely on glycolytic fermentation, an inefficient energy production method compared to oxidative phosphorylation. A ketogenic diet could potentially starve cancer cells by reducing blood glucose concentrations, lowering insulin levels (a hormonal driver of some tumors), and promoting ketones’ metabolic and signaling actions. While it might not serve as a standalone cancer cure, it could complement other treatments and aid in prevention.
Safety First: The Ketogenic Diet’s Track Record
Questions have arisen about the safety of ketogenic diets based on case reports of children with epilepsy experiencing gastrointestinal issues, kidney stones, cardiac problems, and poor growth. However, these reports come with caveats. First, the ketogenic diet used for epilepsy treatment is typically more extreme than recommended for other purposes.
Second, epilepsy patients often have other health problems or medication use predisposing to complications not applicable to the general population. Third, case reports are prone to selection bias, and public health surveillance hasn’t reported widespread adverse events despite the ketogenic diet’s popularity today.
Moreover, any diet focused on a specific macronutrient can have adverse effects if food quality isn’t considered. A low-fat diet high in sugar and processed carbohydrates, for instance, can lead to fatty liver and metabolic syndrome, while an inadequately planned vegan diet can cause growth issues in children.
In fact, there’s no human requirement for dietary fiber or carbohydrates. While some populations that consume high-carbohydrate diets with substantial physical activity have low rates of obesity-related chronic diseases, this isn’t necessarily the case for those with prevalent obesity and insulin resistance.
Moreover, traditional hunter-gatherer societies in temperate and arctic climates have consumed diets virtually devoid of carbohydrates and fiber for centuries.
Both low-fat and low-carbohydrate diets can have adverse effects, especially in individuals with insulin resistance, which is common in the United States. However, a well-structured ketogenic diet seems to be safe for the general population. Based on available evidence, it can be a primary approach to treating obesity and type 2 diabetes, and it also holds promise for various other chronic conditions related to metabolic dysfunction, including type 1 diabetes, steatohepatitis, neurodegenerative diseases, and cancer.
But, despite its potential, high-quality clinical trials are needed to fully understand the long-term effects and capabilities of the ketogenic diet in clinical medicine. Key questions remain, such as how does LDL cholesterol elevation on a ketogenic diet compare to triglyceride elevation on a low-fat diet in terms of cardiovascular risk? Does the reduction in HbA1c levels in diabetes with a ketogenic diet translate to reductions in micro- and macrovascular diseases? And, are there specific populations or conditions for which a ketogenic diet should be avoided?
The ketogenic diet has indeed stirred controversy, partly because conventional nutrition teaching has long emphasized the harms of high total and saturated fat intakes. However, this diet can be adapted to various dietary preferences, including vegetarian and vegan options, making it a flexible choice for those looking to explore its health benefits.