Monday, September 24, 2007

How Do You Feel on Low-Carb?

An interesting short-term study published in this month's American Journal of Clinical Nutrition, Low- and high-carbohydrate weight-loss diets have similar effects on mood but not cognitive performance, sought to assess differences in mood following a high-carbohydrate diet compared with a low-carbohydrate diet.

In the study, ninety-three subjects were randomized into two groups:
  • The high-carbohydrate dieters consuming a calorie restricted diet with 46% carbohydrate, 24% protein and 30% fat. Women consumed approximately 1429-calories each day, or 164g carbohydrate, 48g fat and 86g protein. Men consumed approximately 1667-calories each day, or 192g carbohydrate, 56g fat and 100g protein.
  • The low-carbohydrate dieters consuming a calorie restricted diet with approximately 4% carbohydrate, 35% protein and 61% fat. Women consume approximately the same calories as above (there was no statistically significant difference for calories consumed in the study), or 15g carbohydrate, 97g fat and 125g protein. Men consumed approximately the same calories as above, or 17g carbohydrate, 113g fat and 146g protein.

Throughout the study, over the course of eight weeks, foods were provided to subjects and every two-weeks weight was taken and mood measured. Compliance by those following the low-carb diet was verified by measuring urinary ketone levels.

Both diets resulted in statistically significant weight loss.

The low-carbohydrate diet resulted in a statistically significant greater weight loss over the eight-week period than the high-carbohydrate diet, with low-carb dieters losing an average of 7.8kg (17.2-pounds) compared to 6.4kg (14.1-pounds) in the intent-to-treat analysis (p=0.04).

Both groups showed improvements in psychological well-being (p=0.01 for time) and there was no significant difference in working memory. The researchers noted "[t]here was some evidence for a smaller improvement in cognitive functioning with the LCHF diet with respect to speed of processing, but further studies are required to determine the replicability of this finding."


  1. There is no doubt in my mind that I feel better on the low-carb nutritional approach to good health. Just today I was thinking about how much more energy I have to be able to perform my job. I knew I had some fairly serious brain fog but it is gone! There are other benefits I've experienced, but I'll keep it short for the comment area. This is all at the end of three months of low-carb and 30 pounds weight loss. Low-carb is da' bomb!

  2. Regina, I posted a poll on my site and found asked:

    Adhering to a low carb lifestyle has affected my mood:

    1) Not at all = 7.14%
    2) For the better = 78.57%
    3) For the worse = 3.57%
    4) Not sure - 10.71%

    Interesting stuff, huh?

  3. Anonymous12:11 AM

    I have to say I feel much better on Low Carb. It isn't just the energy thing either it is to me anyway the anti depression diet. I used to feel not quite right & down all the time, not bad enough for medicaiton but since introducing more saturated fat into my diet I feel so much more postive in my outlook on life. Nothing seems to get me down & mood swings seem to be a thing of the past. Cheers helen

  4. Anonymous3:59 AM

    Yes, the brain fog is definitely temporary, in fact the study was so short term I don't think they should have brought up speed processing at all!

  5. Anonymous7:02 AM

    interesting that weight loss was greater on the low carb diet. Do you know how calories were tracked?

  6. MrFreddy,

    My understanding (from the abstract and write-ups on the study) is that food was provided to the dieters. I didn't pay for full-text access, so cannot say I read it myself, but a CME review of the study indicated the subjects were provided food as a means to maintain calorie intakes between groups. HTH

  7. I feel much better on low carb. I used to suffer from brain fog and starting to feel stupid. Now that has cleared up and other people are noticing the improvement as well.

    They say you need at least 130g of carbs per day for proper brain function. That's hogwash. Mine functions better on 1/4 that.

    1. Anonymous11:29 AM

      I have the same brain fog when I eat carbs along with migraines I read that yeast causes that and carbs feed yeast so when you cut out carbs you are not feeding the problem also people with yeast overgrowth are often misdiagnosed with diabetes

  8. Anonymous9:06 AM

    The big difference might be also in the response to stress. As a heavy commuter on one of Europes densest motorway (A31 between Metz and Luxemburg) there are sometimes dangerous situations. Before lowcarb when encountering such a situation I had really difficulties coping with them (fast heart beat, nearly fainting, extremities getting itchy and a long time before recovering). When it happens now I have a faster and more determined reaction and this without any physical change on pulse, sweat and all.
    The overall mood has not changed that much, but I am much more calm in danger situations, that makes a huge difference.

  9. Anonymous7:44 AM

    You have completely misreported this study. The HCLF group is the one that increased in processing speed. Please stop reporting information that is incorrect. Perhaps you should re-read your own link, as the information is clearly stated this way in the abstract. While I am all for low carb, I am not at all for twisting scientific evidence to meet my viewpoint.

  10. Excuse me anon, but I provided a direct quote from the abstract:

    The researchers noted "[t]here was some evidence for a smaller improvement in cognitive functioning with the LCHF diet with respect to speed of processing, but further studies are required to determine the replicability of this finding."

    I do not "twist" things to meet my point of view.

  11. I've found that the lower my carbs are, the more energy I seem to have.

  12. For those who don't quite understand, the study states that both groups had improved mood and mental function, but the low-carb group had a SMALLER increase in the mental processes.

    I didn't need a study to tell me that, I forget things and can't think straight while low-carbing, though I do get a bunch of energy and feel good otherwise. :)

  13. Anonymous12:55 PM

    A low carb diet does show dramatic results, however many people (including myself) find it unrealistic to maintain this lifestyle for the rest of your life. It is much easier to just reduce your calorie intake and increase activity levels.

  14. I wonder if the higher amount of fat in the low carb group influenced better cognitive functioning? Is there any evidence fat in diet affects brain function? Or am I shooting arrows in the dark.

  15. Wow! I'm trying my first-ever experience with low-carb, and I am loving it!

    I'm only on the 4th day, and on this day I feel absolutely fantastic. I feel lighter on my feet, and I have had NO mid-afternoon energy crashes.

    The first couple of days, I felt the so-called "Atkins flu", and felt a bit groggy, but today I feel like I could leap in the air! I'm very energetic, bubbly, and talkative, which is unusual for me.

    I never knew excessive carbohydrates were keeping me down all this time. I'm not even in ketosis right now, but I feel SO much better by getting rid of the sugar and flour!

    Thanks, Regina, for your blog, and for the links to others, like Jimmy Moore, Protein Power, Mark Sisson, and Weston A Price. I've learned a LOT from all these sites.

    1. Anonymous4:53 AM

      This is EXACTLY how I felt also! It's been over two weeks now when I dropped all simple carbs from my diet and concentrated on salads, veggies and protiens. I've never felt so good during the day, wake up much easier and steady energy at the gym without crashes. No more simple carbs for life!

  16. I definitely feel better on low carb, especially when I'm in ketosis.

  17. I tend to get a boost in cognition after a high carb, high cal meal, but if I continue this for any amount of time I feel much worse, most notably emotionally.

    It took many many weeks for my mental function to match what it was before low carb. For the longest time I felt lethargic and out of it. 8 weeks is not long enough, IMO. Their metabolisms may be mildly conserving due to weight loss and sugar withdrawal (very low carb, will suppress the thyroid temporarily).

  18. My experience is my mental health improved amazingly when I went to low carb eating. I was truly amazed and wasn't expecting that as a nice side effect. But on low fat I was found emotional depression...

  19. I made too many simultaneous changes to claim that low-carb is why I feel great. I also started taking 1 tablespoon of fish oil per day, 6000 IU vitamin D, a better multivitamin, 1000mg niacin (flush-tastic!) and then I went on a low-carb diet, too.

    I do feel more uniformly alert: my afternoon "slump" has disappeared (I used to have a crash in the afternoon around 3:30-4:00pm where I would get irritable and easily distracted). Instead of any huge mood or mental energy boost, the most noticeable change is just that I don't switch from high energy to low energy and back several times a day.

    1. Anonymous4:58 AM

      Except for the low bad carb diet part, I didn't do any of those on your first paragraph but got the same results you wrote on your second paragraph.

  20. Anonymous12:11 AM

    It would be interesting to see studies that include the subjects' *starting* diets, to evaluate how much of the low-carb mental impact is due to a greater (or lesser) change.

    I'm feeling fantastic, most of the way through my 1st low-carb week. Brain fog has cleared, energy is up...but I also have to note that my diet previously was almost exclusively carbs. Mostly breads/pastas at that. I'm thinking this was partly self-medicating (bring on the serotonin!) and perhaps too much of a "good" thing. It seems like a different scenario than say, someone who switches to low-carb from a more normal distribution of meats, veggies, and fruits.

    Not leaping to any conclusions, just thinking it might be important to consider frame of reference as studies continue :-)