Brain fog is a real part of dieting for many people, especially those who choose to start a very low carb diet. Low carb diets have many benefits but switching from a diet heavier in carbohydrates to a keto or low carb regimen can be difficult in the beginning! It’s called the keto flu for good reason, as the body switches from using glucose as fuel to ketones, bringing with it all kinds of malaise. Even if you aren’t cutting out carbs entirely, sluggishness and brain fog can make it seem impossible.
Temporary Cognitive Effects
It’s important to remember these effects are temporary, and to remind yourself of all the reasons why you’re making a switch. It could also be helpful to remind those around you that it’s not just all in your head: a study found that reducing carbohydrates directly affects your cognitive skills. From 2008, Tufts University followed healthy adult women who chose to eat a low carb diet or a low-calorie diet that was balanced with macronutrients. It was a small study of only 19 women, but the research team believes they found evidence that reducing carbohydrates resulted in poorer cognitive performance than reducing overall calories.
Participants underwent cognitive testing before, during, and after reintroducing carbs, measuring attention, memory, and visual skills. Tests tracked attention, memory, and visual skills before, during, and after carb reintroduction for low-carb participants. The dieters on the low carb plan experienced a steady decline in memory. Their reaction time became slower, and visual and spatial memory performance was lower than those in the low-calorie group. However, researchers found a silver lining—low-carb dieters exhibited improved attention. Researchers attribute this to the low-carb diet’s higher protein and fat content, known to enhance short-term memory.
Did the participants notice any difference when carbs were restricted versus when calories were restricted? Surprisingly, both groups reported no difference in hunger, but the low-calorie group experienced confusion at the study’s midpoint.
Dietary Trade-offs: Cognitive Impact
Clearly, there are trade offs when choosing one diet plan over the other! Low-carb diets, restricting glucose, may cause cognitive decline since the brain depends on glucose for energy. Cognitive decline on low-carb diets stems from the brain’s reliance on glucose for energy. Lower levels of glucose impact the brain’s functioning and energy reserves. Differentiate between low-carb and keto diets; the latter shifts the brain’s energy source from glucose to ketones. Keto diets prioritize ketones over glucose for brain fuel, unlike traditional low-carb diets.
Skipping carbs for protein may slow cognitive function; accepting this can prompt precautionary measures during tasks like driving. Understanding cognitive delays from skipping carbs can prompt caution, like setting extra reminders and driving more attentively.
Further Reading
Danci et al. Low-carbohydrate weight-loss diets. Effects on cognition and mood. Appetite, 2009; 52 (1): 96 DOI: 10.1016/j.appet.2008.08.009
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