Low-carb diets can affect dieters' cognition skills

December 12, 2008

Tufts study compared women's cognition on low-carb and reduced-calorie diets


MEDFORD/SOMERVILLE, Mass. -- A new study from the psychology department at Tufts University shows that when dieters eliminate carbohydrates from their meals, they performed more poorly on memory-based tasks than when they reduce calories, but maintain carbohydrates. When carbohydrates were reintroduced, cognition skills returned to normal.

"This study demonstrates that the food you eat can have an immediate impact on cognitive behavior," explains Holly A. Taylor, professor of psychology at Tufts and corresponding author of the study. "The popular low-carb, no-carb diets have the strongest potential for negative impact on thinking and cognition."

Taylor collaborated with Professor Robin Kanarek, former undergraduate Kara Watts and research associate Kristen D'Anci. The study, "Low-carbohydrate weight-loss diets. Effects on cognition and mood," appears in the February 2009 edition of the journal "Appetite."

While the brain uses glucose as its primary fuel, it has no way of storing it. Rather, the body breaks down carbohydrates into glucose, which is carried to the brain through the blood stream and used immediately by nerve cells for energy. Reduced carbohydrate intake should thus reduce the brain's source of energy. Therefore, researchers hypothesized that diets low in carbohydrates would affect cognitive skills.

Study participants included 19 women ages 22 to 55 who were allowed to select the diet plan they preferred -- either a low-carbohydrate diet or a low-calorie, macronutrient balanced diet recommended by the American Dietetic Association. Nine women chose a low-carbohydrate diet and 10 selected the low-calorie diet.

"Although the study had a modest sample size, the results showed a clear difference in cognitive performance as a function of diet," says Taylor.

The 19 dieters completed five testing sessions that assessed cognitive skills, including attention, long-term and short-term memory, and visual attention, and spatial memory. The first session was held before participants began their diets, the next two sessions occurred during the first week of the diet, which corresponded to the week when low-carb dieters eliminated carbohydrates. The final two sessions occurred in week two and week three of the diets, after carbohydrates had been reintroduced for those on the low-carb diet.

"The data suggest that after a week of severe carbohydrate restriction, memory performance, particularly on difficult tasks, is impaired," Taylor explains.

Low-carb dieters showed a gradual decrease on the memory-related tasks compared with the low-calorie dieters. Reaction time for those on the low-carb diet was slower and their visuospatial memory was not as good as those on the low-calorie diet. However, low-carb dieters actually responded better than low-calorie dieters during the attention vigilance task. Researchers note that past studies have shown that diets high in protein or fat can improve a person's attention in the short-term, which is consistent with the results in this study.

Participants were also asked about their hunger levels and mood during each session. The hunger-rating did not vary between participants on a low-carb diet and those on a low-calorie diet. The only mood difference between dieters was confusion, which was higher for low-calorie dieters during the middle of the study.

"Although this study only tracked dieting participants for three weeks, the data suggest that diets can affect more than just weight," says Taylor. "The brain needs glucose for energy and diets low in carbohydrates can be detrimental to learning, memory, and thinking."

Tufts University

---

---

	The 10/60 Diet: How to lose 10% of your body weight in 60 days. With all of the diet books on the market today, where is a person to turn? Pages upon pages of fluff with doctored before and after pictures; indiscernible scientific mumbo-jumbo; diet and exercise regimens that are impossible to follow and maintain. What if someone trimmed the fat from diet book and provided a simple plan to lose ten percent of your body weight within sixty days? Here it is. It costs under $1, it's under twenty pages, and it's all you need to find your beautiful new body, which has been hiding within you all along. The author used this diet to go from 194 pounds to 172 pounds between January 28, 2011 and March 28, 2011. How many authors can show results from the diets they recommend? Invest $0.99 and a few minutes of your time...
	The Protein Express Diet: Rapid Weight Loss with a Simplified Dukan / Atkins Style Low-Carb Diet by OSK Publishing The Protein Express Diet is a proven protein-intensive, low-carb diet with a strong emphasis on fast and easy food preparation. It is a rapid weight loss diet that is ideal for busy people who often find themselves relying on fast food or processed, easy-to-prepare meals. The Protein Express Diet offers a simple 5-step plan for rapid weight loss, as well as a specific strategy for avoiding weight regain once reaching your goal. The book is full of tips, techniques and strategies that can be used either independently or in conjunction with nearly any other low-fat or low carb diet. The book also covers exercise and thermal weight loss techniques, and introduces a revolutionary way to burn more calories while walking. The book is concise (but still...
	New Atkins for a New You: The Ultimate Diet for Shedding Weight and Feeling Great. by Eric C. Westman (Author), Stephen D. Phinney (Author), Jeff S. Volek (Author) Think you know the Atkins Diet? Think Again. The New Atkins is... Powerful: Learn how to eat the wholesome foods that will turn your body into an amazing fat-burning machine. Easy: The updated and simplified program was created with you and your goals in mind. Healthy: Atkins is about eating delicious and healthy food -- a variety of protein, leafy greens and other vegetables, nuts, fruits, and whole grains. Flexible: Perfect for busy lifestyles: you can stick with Atkins at work, at home, on vacation, when you're eating out -- wherever you are. Backed by Science: More than 50 studies support the low-carb science behind Atkins. But Atkins is more than just a diet. This healthy lifestyle focuses on maintenance from Day 1, ensuring that you'll not...
	1,001 Low-Carb Recipes: Hundreds of Delicious Recipes from Dinner to Dessert That Let You Live Your Low-Carb Lifestyle and Never Look Back by Dana Carpender (Author) This tasty collection draws on the best 1,001 recipes from Dana Carpender’s bestselling books including 500 Low-Carb Recipes, 15-Minute Low-Carb Recipes, 500 More Low-Carb Recipes, 200 Low-Carb Slow Cooker Recipes, The Low-Carb Barbeque Book, and Low-Carb Smoothies. You’ll find delicious and varied options including recipes for "high-carb" foods you thought you had to give up forever such as Cinnamon Raisin Bread and Mocha Chocolate Cheesecake. Staying the low-carb course will be easy with choices from barbecue to slow-cooker to internationally-inspired dishes.
	Low-Carb Dieting For Dummies  by Katherine B. Chauncey (Author) Reduce your weight, your cholesterol, and your blood pressureGet the facts about carbs and get serious about improving your healthCurious about going low-carb? This plain-English guide explains the latest research behind reduced-carbohydrate diets, dispelling the myths and revealing how to navigate your way through the good and bad carbs to create a diet plan that works! You get delicious recipes and lots of tips to make your low-carb diet a success.Discover how to:Stock a low-carb kitchenPrepare 75 tasty low-carb recipesEat right while dining outCreate both meat and vegetarian dishesIncorporate exercise into your dayMaintain a low-carb lifestyleThe Dummies WayExplanations in plain English"Get in, get out" informationIcons and other navigational aidsTear-out cheat sheetTop ten listsA dash...
	Carb Charts - Low Carb Reference When you're out and about, do you wish you could know the carb value in the food you're thinking about ordering? This 67 page carb chart book keeps you on a healthy path. It's important to eat foods that are low in sugar and starch. We all know that. But how do we know which foods are better than others? This handy carb chart provides the solution, no matter what style of diet you are on. No more guessing at what a food will 'cost you' while out at a supermarket or at a restaurant. This useful book provides all the details you need to create a more healthy you! From fruits and vegetables to nuts and berries, you will have the data you need at your fingertips. There is also complete coverage of popular low carb beers, liqueurs, whiskeys, and more. All four...
	The 30-Day Low-Carb Diet Solution by John Wiley & Sons, Inc. From the authors of the phenomenal bestseller Protein Power comes a quick, easy-to-follow low-carb diet plan designed to get you on the fastest possible track to losing weight, feeling fantastic, and improving your health. If you've heard all the recent publicity about how low-carb eating can turn your health around - by keeping your insulin levels down and getting your excess weight off - but don't want to wade through hundreds of pages of explanation or complicated formulas before you get started, The 30-Day Low-Carb Diet Solution is for you. Unlike any other low-carb diet book in the market, this book gives you low-carb 101: the basics of low-carb eating without all the fuss. In this much-needed book, two of the most trusted names in low-carb dieting who have helped millions...
	CRASH Diet Plans for Women by MakeRight Publishing If you are interested in doing a "crash diet" to lose weight very quickly (and do it in a safe and simple way) then this new book by bestselling diet author Jennifer Jolan is "must reading." The book is called: "Crash Diet Plans For Women" And it covers the seven most popular crash diets being hyped and promoted in the media. However, a word of warning: Every single one of these diets can be dangerous to your health. And, in some cases, can cause you to get very sick or worse! However, since women are doing these diets anyway, Jennifer Jolan has decided to write a book showing you ALL the facts about each one so you can take the GOOD parts of each diet and incorporate them into a healthy diet and eating plan...
	Thin for Good: The One Low-Carb Diet That Will Finally Work for You by Fred Pescatore M.D. (Author) A REVOLUTIONARY PERSONALIZED PROGRAM FOR LIFELONG THINNESS Taking low-carb diets to the next level, Thin for Good combines clinically tested, up-to-the-minute nutritional advice with an added bonus: a revolutionary mind-body program designed to eliminate your cravings. Leading you through the eleven emotional levels of eating, Dr. Pescatore shares his unique solutions to the psychological roadblocks we all face when trying to lose weight. The result is a thirty-day plan--filled with affirmations, self-evaluations, and exercises--that will get you on the road to lifelong thinness. Customized for your sex and stage of life, filled with delicious recipes and meal plans, Thin for Good gives you the fuel you need for your lifestyle. Get thin for good--now and forever. "Thin For...
	25 Quick & Easy Low Carb Breakfast Recipes: Delicious Food That Helps You Stick to Your Diet Do you love your low carb diet, but can't face another plate of bacon and eggs in the morning? The #1 Best Seller, 25 Quick and Easy Low Carb Breakfast Recipes is here to rescue you from dietary boredom with mouthwatering breakfast recipes that will help you stick to your diet and get the results you want. Eating a delicious low carb breakfast has never been easier to do than with this especially-formatted for the Kindle book. In 25 Quick and Easy Low Carb Breakfast Recipes you get: Easy Recipes for fabulous breakfasts you can enjoy yourself or prepare for your entire family. You'll spend less time in the kitchen while still staying on your diet.Effort-free carb counting: clear carbohydrate and fiber counts, as well as full nutritional information is provided for each...