March Newsletter | Ketogenic Diet for Epilepsy and Obesity: Is it the Same?

Tagliabue A et al.. Ketogenic diet for epilepsy and obesity: Is it the same?, Nutrition, Metabolism & Cardiovascular Diseases.  https://doi.org/10.1016/j.numecd.2024.01.014

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KEY POINTS

• Ketogenic diets encompass various protocols inducing different levels of ketosis, from weight loss regimens like VLCKD (very low calorie ketogenic diet) to therapeutic diets for neurological diseases.

• VLCKDs for weight loss achieve ketosis through calorie restriction, while standardized protocols like the classic ketogenic diet are designed for therapeutic ketosis.

• Clinical applications of ketogenic diets extend beyond epilepsy, with varying dietary compositions ranging from low-carb, high-protein regimens to very-low-energy diets, all abbreviated as VLCKD.

• Clear terminology and ketone level measurement are essential, with "ketogenic dietary therapy" best reserved for conditions where ketosis is integral to treatment.

INTRODUCTION

The term "ketogenic diet" (KD) is used for various types of diets that have different purposes, like treating epilepsy or helping with weight loss. However, some diets called "ketogenic" might not actually cause ketosis, which is when your body produces and maintains ketone bodies. Ketosis is important for certain conditions like epilepsy but might not be necessary for weight loss.

For epilepsy treatment, a ketogenic diet typically involves high fat and low carbohydrate intake, carefully calculated to ensure enough calories for growth. However, in weight loss diets, ketosis is usually induced by restricting calories rather than by the specific ratio of fats, proteins, and carbohydrates.

Different terms have been suggested to clarify the types of ketogenic diets, like "very low-calorie," "low-calorie," and "eucaloric" ketogenic diets, based on their carbohydrate content and calorie levels. Despite these efforts, there's still no widely agreed-upon definition of a ketogenic diet. It's not just about cutting carbs; the ratio of nutrients and calorie intake also matters.

What exactly is the ketogenic diet?

A ketogenic diet boosts ketone levels in the body, mimicking fasting but supporting growth. Types include Classic, MCT (medium chain triglyceride) diet, Modified Atkins, Very Low-Carbohydrates, and Very Low-Calorie Ketogenic Diets. The level of ketosis varies; for neurological diseases, it's higher (4-5 mmol/L), while for weight loss, it's milder (0.5-1.2 mmol/L), both safe. It's crucial to specify the intended ketosis level for each condition.

The Ketogenic Potential

The level of ketone production in a diet, known as its "ketogenic potential," depends on the nutrients consumed and whether there's enough glucose available. Ketosis, where the body produces ketone bodies, happens when there's insufficient glucose, either due to carbohydrate restriction or severe calorie restriction (like fasting).

For carbohydrate restriction, the ketogenic potential depends on the ratio of ketogenic (fats) to non-ketogenic (proteins and carbohydrates) nutrients, called the ketogenic ratio. A ratio of fats to proteins plus carbohydrates of 2:1 for example induces ketosis, used in treating conditions like epilepsy.

In severe calorie restriction, energy comes from both dietary and stored fat. The total ketogenic ratio considers both dietary and endogenous (stored) fat, crucial for hypocaloric diets.

Commercial “Keto” Products

The confusion in terminology extends to commercial products labeled as "ketogenic." While some are high-fat products designed for treating neurological diseases, others marketed for weight loss are high-protein and low-carbohydrate, with little fat. True ketogenic products have a medium to high ketogenic ratio, containing fats as a main component. Conversely, high-protein, low-carbohydrate products lack ketogenic potential despite being labeled as "ketogenic." This distinction is vital for patients and nutrition specialists to ensure the correct dietary plan is prescribed.

Ketogenic diet and Side Effects

Ketogenic diets, like any medical therapy, can have potential adverse effects that vary depending on several factors:

1. Type of Ketogenic Diet: Different diets (e.g., Classic, MCT, MAD) have varying risks of side effects.

2. Level of Ketosis: Achieving different levels of ketosis can influence side effect occurrence.

3. Duration of Dietary Therapy: Long-term use may lead to different adverse effects compared to short-term.

4. Overall Diet Quality: The proportion of plant-based versus animal-based fats and proteins can affect risks.

For epilepsy treatment, serious adverse events are rare, but long-term ketogenic diet use may lead to issues like hyperuricemia, hyperlipidemia, kidney stones, osteopenia, and delayed growth in children. Careful diet planning, including Mediterranean patterns and plant-based fats/proteins, helps mitigate risks.

Very-low-calorie diets (<800 kcal/day) for severe obesity have side effects like dehydration, hypoglycemia, nausea, vomiting, diarrhea, constipation, and halitosis. Self-prescribed Atkins-like diets without supervision can raise LDL-cholesterol, cause hypoglycemia, and lead to nutrient deficiencies.

Conclusion: The term "ketogenic diet" is imprecise as different protocols induce varying levels of ketosis. While VLCKDs for weight loss may not be inherently ketogenic, they trigger ketosis through calorie restriction. Conversely, standardized protocols like the classic ketogenic diet target therapeutic ketosis in neurological diseases. In clinical applications beyond epilepsy, ketogenic diets range from low-carb, high-protein regimens to very-low-energy diets, all abbreviated as VLCKD. Clear terminology and ketone level measurement are crucial, with "ketogenic dietary therapy" reserved for conditions where ketosis is important.

Our viewpoint highlights that ketogenic diets for epilepsy and obesity are not the same. Researchers should specify the dietary protocol, nutritional composition (fat, protein, carbohydrates), ketogenic ratio, and target level of ketosis in their studies. Correct abbreviations, such as VLCHKD for Very Low CarboHydrate Ketogenic Diet and VLEKD for Very Low Energy Ketogenic Diet, should be used to clarify differences in composition.