Repeatedly gaining and losing weight (yo-yo dieting) can slow metabolism and pose risks to your overall health. Now, scienctific studies are questioning whether these diets are dangerous to your brain's memory function, too.
Low-carbohydrate diets are notoriously difficult to adhere to for long periods of time. Many of my patients have tried a low-carb diet and lost weight, some over 100 pounds, but most often the weight came back... and then some. Repeatedly gaining and losing weight (yo-yo dieting) can slow metabolism and pose risks to your overall health. Now, scientific studies are questioning whether these diets are dangerous to your brain's memory function, too.
Slower brain functions
Researchers at Tufts University have found that dieters who strive to eliminate most carbohydrates from their diets scored significantly lower on memory-based tasks than did subjects who simply reduced the amount of calories they ate.
The study subjects included 19 women ages 22 to 55, 9 of whom were put on a low-carbohydrate diet and 10 on a low-calorie but balanced diet. All subjects attended 5 memory-testing sessions in which their spatial memory, attention, cognitive skills, and short and long-term memory were assessed. These sessions were conducted throughout the 3 weeks of the study.
After 1 week of severe carbohydrate restriction, memory performance among the low-carb group, especially when dealing with difficult tasks, gradually decreased compared with the low-calorie group. In addition, the low-carb dieters had slower reaction times and faltered during tests of their visual-spatial memory.
Feeding the brain
The brain uses glucose as its main fuel but has no way of storing it for future use. The nerve cells use glucose immediately for energy, and if they cannot get this fuel, they aren't able to operate at peak capacity -- potentially leaving you feeling forgetful or unable to concentrate.
I read a study recently that found students and others who continually challenge their minds actually require more carbohydrates, and thus, seem to crave carbohydrate foods in direct proportion to how much they have to exert their brains. Perhaps carbohydrate cravings in such cases are the body's way of getting the brain the fuel it needs.
This study only tracked the dieters for 3 weeks and the study's sample size was small, but the authors suggest that, although low-carb diets can affect weight, they result in a lack of glucose to the brain that may be detrimental to learning, memory, and thinking.
According to the Tufts study, the popular low-carb diets—and particularly the "no-carb" diets—have the biggest potential for decreasing the ability to think and concentrate, and may also negatively affect overall mood. This could be one of the reasons many people have a hard time sticking with a no-carb meal plan.
What you need to know
I'd love to hear your thoughts and experiences with low-carb diets, dear readers.