Can Low-Carb Diets Impair Brain Function?

Chances are, you have many friends or family members that have been lured into eating one of the many types of low-carb diets. These high animal protein, carbohydrate restrictive diets promise quick weight loss results without having to exert much effort. Dieters enjoy the fact that they can lose weight rapidly without having to give up the foods that their body craves. Increasing their intake of bacon, steak and butter while severely cutting out fruits, starchy vegetables, whole grains and beans is what makes low-carb dieting so appealing. If it sounds too good to be true...it is. Low-carb diets that are based on animal products not only pose serious long-term health risks, they have been associated with a significantly higher all-cause mortality, as well as cardiovascular mortality and cancer mortality in both men and women.

This blog is just one of many that will expose the dangers and extraordinary claims that are the cornerstone of every low-carb diet. It will focus on brain impairment, which is just one of the countless side effects experienced by those following the Atkins diet.

To demonstrate how low-carb diets impair brain function, we must first grasp a basic understanding of how carbohydrate-rich foods are the body’s preferred source of fuel. The body utilizes carbohydrates very efficiently by breaking them down into a useable source of energy -- glucose. Glucose is stored (as glycogen) in our muscles and liver in limited quantities. When needed, it is converted back into glucose and released into the bloodstream.

However, the body cannot store large quantities of glycogen, so it must rely on a continual dietary source of carbohydrate to replenish these reserves. When dietary carbohydrates are severely restricted as in an Atkins-type diet, the body’s glucose reserve is depleted within just a few days. The body is then forced into utilizing stored fat as well as dietary fat for fuel. This inefficient metabolic process produces acidic by-products called ketones. Ketosis is a metabolic state that is seen in those that are severely ill and/or are literally starving to death. Loss of appetite is nature’s gentle way of reducing hunger pains for those who are nearing death. Ketones produce a mild euphoria -- almost like a natural anesthetic. This explains why low-carb dieters lose their appetite.

While the brain represents only about 2% of the adult body, it requires about 20-30% of the body’s total energy requirement. Glucose (from carbohydrate) is the brain’s primary fuel, but it cannot be stored in the brain. After it is metabolized, it is carried to the brain cells (neurons) via the bloodstream. If the body's glucose reserves are depleted, a fuel deficit occurs and brain cells aren’t able to function optimally. Fatigue, brain fog, confusion, and moodiness are symptoms which affect one’s ability to reason and solve problems. In order to compensate for this deficet, ketones are used for fuel. These symptoms are commonly seen in those following low-carb diets and raises the question whether or not carbohydrate restriction impairs cognitive function. It appears that it may. Several studies have emerged noting that restricting the intake of carbs can impair short and long-term cognitive performance.

For example, the study Low-Carbohydrate Weight-Loss Diets. Effects on Cognition and Mood conducted on women and published in February of 2009 in the journal Appetite, revealed that after one week of beginning an Atkins-type diet the women performed worse on memory-based tasks. Their reaction times were slower and their visual-spatial memories were affected. Prior to starting the diet, the women were tested to measure long- and short-term memory and attention. Testing was repeated at one, two, and three weeks after beginning the diet. These impairments were alleviated after the reintroduction of carbohydrates into their diet. The data suggests that memory impairment occurs when carbohydrate (glycogen) levels are at their lowest and highlights the importance of adequate blood glucose for crucial brain function. Researchers concluded, “It is plausible, therefore, to propose that very low carbohydrate diet plans may have longterm effects on cognitive functioning in individuals following such diets in comparison to individuals consuming adequate levels of carbohydrate.”

In a similar study conducted on rats where carbohydrate-rich foods were restricted and replaced with high-fat foods, the rats exhibited severe brain impairment when learning and memory tests were performed.

As a side note, with regards to declining glucose levels in the brain and how it affects cognitive function, an interesting study published in the journal Nutrition suggests that "impaired brain glucose metabolism may contribute to the development of Alzheimer's Disease."

It’s hard to resist the promises that low-carbohydrate diets offer like still being able to enjoy your favorite high-fat foods and effortless weight loss without hunger pains. However, it’s important to mention that low-carb dieters lose weight as long as ketosis (a state of metabolic illness and starvation) is maintained. As soon as carbohydrates are reintroduced back into the diet, all of the body fat that was lost will be gained back. Although these diets are very popular, serious concerns beyond just weight loss should be considered.

The good news is that eating an oil-free diet based on whole unprocessed plant foods is the safest way to lose weight and has a profound (positive) impact on overall health. The side effects include permanent weight loss, optimal immune function, and prevention and reversal of a myriad of acute and chronic disease. Now THAT’S certainly worth checking into, wouldn’t you agree?

Additional Information:

(1) Are You "Dying" to Lose Weight?

(2) Low-Carb Diets Impair Blood Flow

(3) Low-Carb Diet = Higher Rate of Mortality