Science and Low Carb / Paleo

This page summarizes some of the science behind low carb / paleo diets.

Bottom line

The latest review of all major trials of low carb diets show improved weight AND improvement of all major risk factors for heart disease:

Saturated fat

Despite half a century of research there is still no evidence that natural saturated fat (like butter, eggs etc.) is anything but completely safe to eat.

Have a look at these recent reviews of all the evidence:

Insufficient evidence of association is present for intake of … saturated or polyunsaturated fatty acids; total fat … meat, eggs and milk.

There were no clear effects of dietary fat changes on total mortality or cardiovascular mortality…

no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD.

But wait, what about butter and other high fat dairy specifically? Well, actually people consuming it are if anything thinner and healthier than others:

The observational evidence does not support the hypothesis that dairy fat or high-fat dairy foods contribute to obesity or cardiometabolic risk…

This means that the scientific foundation of the low fat dietary advice has fallen. The reasons for it today are mainly economical (low fat high sugar products are very lucrative and finances a lot of lobbying), combined with old-fashioned prestige and inertia.

The low fat dietary advice has become a house of cards with nothing to support it. It is just a question of time before it’s apparent to everybody.

Weight loss

Some people still claim that weight loss studies do not show any advantage for low carb diets. Unbelievably enough, that is what many so called experts still believe.

It’s either ignorance or science denial.

There are at least 18 modern scientific studies of the highest quality (RCT) that show significantly better weight loss with low carb diets:

RCTs showing significantly more weight loss with low carb diets

  1. Shai I, et al. Weight loss with a low-carbohydrate, mediterranean, or low-fat diet. N Engl J Med 2008;359(3);229–41.
  2. Gardner CD, et al. Comparison of the Atkins, Zone, Ornish, and learn Diets for Change in Weight and Related Risk Factors Among Overweight Premenopausal Women. The a to z Weight Loss Study: A Randomized Trial. JAMA. 2007;297:969–977.
  3. Brehm BJ, et al. A Randomized Trial Comparing a Very Low Carbohydrate Diet and a Calorie-Restricted Low Fat Diet on Body Weight and Cardiovascular Risk Factors in Healthy Women. J Clin Endocrinol Metab 2003;88:1617–1623.
  4. Samaha FF, et al. A Low-Carbohydrate as Compared with a Low-Fat Diet in Severe Obesity. N Engl J Med 2003;348:2074–81.
  5. Sondike SB, et al. Effects of a low-carbohydrate diet on weight loss and cardiovascular risk factor in overweight adolescents. J Pediatr. 2003 Mar;142(3):253–8.
  6. Aude YW, et al. The National Cholesterol Education Program Diet vs a Diet Lower in Carbohydrates and Higher in Protein and Monounsaturated Fat. A Randomized Trial. Arch Intern Med. 2004;164:2141–2146.
  7. Volek JS, et al. Comparison of energy-restricted very low-carbohydrate and low-fat diets on weight loss and body composition in overweight men and women. Nutrition & Metabolism 2004, 1:13.
  8. Yancy WS Jr, et al. A Low-Carbohydrate, Ketogenic Diet versus a Low-Fat Diet To Treat Obesity and Hyperlipidemia. A Randomized, Controlled Trial. Ann Intern Med. 2004;140:769–777.
  9. Nichols-Richardsson SM, et al. Perceived Hunger Is Lower and Weight Loss Is Greater in Overweight Premenopausal Women Consuming a Low-Carbohydrate/High- Protein vs High-Carbohydrate/Low-Fat Diet. J Am Diet Assoc. 2005;105:1433–1437.
  10. Krebs NF, et al. Efficacy and Safety of a High Protein, Low Carbohydrate Diet for Weight Loss in Severely Obese Adolescents. J Pediatr 2010;157:252-8.
  11. Summer SS, et al. Adiponectin Changes in Relation to the Macronutrient Composition of a Weight-Loss DietObesity (Silver Spring). 2011 Mar 31. [Epub ahead of print]
  12. Halyburton AK, et al. Low- and high-carbohydrate weight-loss diets have similar effects on mood but not cognitive performance. Am J Clin Nutr 2007;86:580–7.
  13. Dyson PA, et al. A low-carbohydrate diet is more effective in reducing body weight than healthy eating in both diabetic and non-diabetic subjects. Diabet Med. 2007 Dec;24(12):1430-5.
  14. Keogh JB, et al. Effects of weight loss from a very-low-carbohydrate diet on endothelial function and markers of cardiovascular disease risk in subjects with abdominal obesity. Am J Clin Nutr 2008;87:567–76.
  15. Volek JS, et al. Carbohydrate Restriction has a More Favorable Impact on the Metabolic Syndrome than a Low Fat Diet. Lipids 2009;44:297–309.
  16. Partsalaki I, et al. Metabolic impact of a ketogenic diet compared to a hypocaloric diet in obese children and adolescents. J Pediatr Endocrinol Metab. 2012;25(7-8):697-704.
  17. Daly ME, et al. Short-term effects of severe dietary carbohydrate-restriction advice in Type 2 diabetes–a randomized controlled trial. Diabet Med. 2006 Jan;23(1):15–20.
  18. Westman EC, et al. The effect of a low-carbohydrate, ketogenic diet versus a low- glycemic index diet on glycemic control in type 2 diabetes mellitus. Nutr. Metab (Lond.)2008 Dec 19;5:36.

The first 16 studies in the list are weight loss trials, the last two are studies on type 2-diabetics (usually overweight) showing the same effect. Many of the studies are of six months or one year duration, one of them (Shai et al) is two years long.

All of these studies show significantly more weight loss for the group that were advised to eat a low carb diet (Atkins, in most cases).

As far as I know the opposite has never been shown: low carb has never lost a weight loss trial significantly. This means that low carb is winning versus the failed low fat/low calorie advice by 18-0!

Feel free to let me know of any exceptions (or more examples) in the comments.

Update an expert

It’s not OK for “experts” to keep denying all these modern trials. It’s time for them to take the science seriously.

Feel free to copy or link to this list, if you encounter an expert who needs an update.

The science of low carb

Here is the opinion of a true expert on low carb diets, dr Eric C. Westman, MD and president elect of the ASBP (weight loss doctors):

More

LCHF for beginners

Science for smart people

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157 Comments

  1. Eddie
    Ken - my 'yes' is to agree with you that 'no-one has ever proven...'
    My point is that we need to regain the body's ability to provide us feedback as to how much we have eaten. Regular consumption of concentrated fructose (ie usually any cane sugar, honey, HFCS, etc) robs us of our appetite control. Hence, most people can't help but over-consume calories.
  2. Guido Vogel
    Hi Andreas,

    What do you think of this article that states that there is almost no difference in different diets?

    http://jama.jamanetwork.com/article.aspx?articleid=1730520

  3. Kim
    Hi,
    Just saw some tips about reducing the chances of getting Alzheimer's, and one was to reduce saturated fat: http://health.yahoo.net/articles/alzheimers/photos/7-ways-lower-alzhe...

    What are your thoughts about this?

  4. Eddie
    Kim - the Yahoo article provides a glib answer - a bit like a 'sound-bite'.
    I searched on 'beta-amyloid plaques' in association with oxidised cholesterol, and while the wealth of academic papers are way above my head, I did see the dangers of oxidation of cholesterol in the brain mentioned a number of times, and yet not really any differentiation of why the cholesterol was oxidating in the first place, although it did explain how it accelerates and gains association with Alzheimer's. I'd like to see the same research done comparing to diets where all polyunsaturated fat is removed.
    One paper mentioned the terrible efects of increasing cholesterol in rabbits - I did read a comment on this earlier, that rabbits don't take in huge amounts of cholesterol (think lettuce etc) and that any clinically introduced amounts are dispropotionately toxic.... if so, thats just bad science.
  5. Kim
    Eddie,
    Thanks for your comments; interesting. I'm just as confused now as I was before I started LCHF earlier this summer. I was just reading about PUFAs, MUFAs, and oleic acid in Wikipedia, and found it a bit scary that it mentioned, "oleic and monounsaturated fatty acid levels in the membranes of red blood cells have been associated with increased risk of breast cancer. "
    I am obese and my doctor is on my case all the time to lose 20 kg to reduce my cancer risks, and it's very confusing to me to know which sort of eating plan to follow now that I thought I had found something that made sense (LCHF). The arguments for LCHF are extremely convincing, yet it does give me pause when I consider how much more sat fat and MUFAs I've been consuming since starting on LCHF. Dementia and cancer are things we all want to avoid.
  6. sonali
    plese give me the diet plan to losse waitwe
    Reply: #158
  7. Eddie
    Hi Kim and sonali. Search for either/both 'David Gillespie', 'Robert Lustig'. Both authors speak of the great advantages of eliminating 'processed fructose' from our diet. There is quite a bit involved in eliminating ALL forms of processed fructose - it is everywhere in almost any processed food, in the form of CANE SUGAR (ie plain 'ol table sugar, or just 'sugar'). The tragedy is that we have lost our appetite control due to this form of fructose being in most modern diets
    I am most familiar with David Gillespie's 'Sweet Poison' and 'Big Fat Lies' regarding dangers of processed fructose (cane sugar or HFCS, etc) and seed oils (canola, sunflower, generic 'vegetable oil'). Search on either of these book titles for more information. All the best!
  8. ES
    plese give me the diet plan to losse waitwe

    Atkins.

  9. ES
    no one has ever been able to prove you can eat any food in calories above your body's maintenance and lose weight.. I challenge anyone to prove it...

    How about this guy?

    http://www.dietdoctor.com/what-happens-if-you-eat-5800-calories-daily...

    But, you're not using very precise terms here. When you say "your body's maintenance" what exactly does that mean? By my definition (Basal Metabolic Rate) it has been proven. But I have a feeling you mean something else.

  10. Gabrielle Bauer
    It's entirely possible to lose weight on a high-carb diet. Two years ago I lost 50 pounds in 10 months eating 1,500 cals per day, of which about 60% was carbs. Today I continue to maintain my lower weight on 2,000-cal, 60% carb diet. I exercise regularly and my lab values are all fine. Works for me.
  11. Pekka Huttunen
    A year ago I was 30+ pounds heavier, had joint issues, heartburn, skin inflammation, poor cholesterol readings, etc. Now I am feeling energetic, good cholesterol is way up, size of bad cholesterol particles is big (study about this when you have a moment) which is good news. I also suffered from gout. I haven't had an episode for over six months. Believe me, low carb and no wheat works.

    I eat lots of eggs, grass fed beef, salmon, other seafood, vegetables and salads. For desert I eat a piece of chocolate.

  12. Samantha
    Women Vs. Men and LCHF Vs. Mediterranean

    I just want to highlight this information from the NEJM study sited in Item 1 above.
    Women did much better on the Mediterranean Diet over 2 years.

    Among the 277 male participants, the mean 24-month weight changes were

    −3.4 kg for the low-fat group,
    −4.0 kg Mediterranean-diet group
    −4.9 kg low-carbohydrate group.

    Among the 45 women, the mean 24-month weight changes were
    −0.1 kg for the low-fat group,
    −6.2 kg for the Mediterranean-diet group
    −2.4 kg for the low-carbohydrate group

    The similar caloric deficit achieved in all diet groups suggests that a low-carbohydrate, non–restricted-calorie diet may be optimal for those who will not follow a restricted-calorie dietary regimen.

    The present study has several limitations. We enrolled few women; however, we observed a significant interaction between the effects of diet group and sex on weight loss (women tended to lose more weight on the Mediterranean diet), and this difference between men and women was also reflected in the changes in leptin levels. This possible sex-specific difference should be explored in further studies.

  13. Katharina
    Thanks for sharing your thoughts about how to lose weight fast.
    Regards
  14. 1 comment removed
  15. Simon
    What about 'free' or 'cheat' days while on a LCHF diet? Can I have them, as I find it difficult to maintain a strict nutritional eating plan without them. If I do have a 'cheat' day, will my body switch back from being ketogenic, and will I have to do the transition period all over again?
    Thanks.
    Reply: #166
  16. Zepp
    I can tell that almoste everyone that get on a ketogenic diet do falls of the wagon now and then.. thats natural!

    Even diabetics fall of the wagon.. and they do get more damage by that!

    And ofcourse one falls out of ketosis.. but if one is healty its not that important!

    But if you are able to eat ketogenic for some months, then you are able to switch back without having transitation problems again!

  17. barbara timperley
    The butter lie is just that,a lie,so is the animal fat lie.Just a little look at history will result in the observation that before all this nonsense came out,everyone ate butter and meat fat.There was nary any obesity in the early 1900 to 1950,enter margarine, soda pop,trans fat etc.and the big lie of animal fat.I continue to eat a high animal and dairy fat diet. as i always have,I am thin and healthy.
  18. Sue Kiernan
    I'm considering going on a ketogenic, low carb/high fat diet to combat cancer. My question/concern is: I cannot afford to lose any weight. How is this diet recommended for cancer patients, when said patients have to maintain or gain weight?
  19. Martin Levac
    @Sue Kiernan

    Are you talking about cachexia? That's lean tissue wasting, associated with some pathology, including cancer. Here's an idea. If you go LCHF to combat cancer, and since we're talking about _cancer_ cachexia, won't you have a better chance of combating cachexia with LCHF too? Think of it as fuel distribution. LCHF returns fuel distribution back to normal, by giving less fuel to fat tissue, and more fuel to lean tissue. Not just fuel, also protein and all the other good stuff. The point is if LCHF gives more to lean tissue, right there you combat cachexia, whether you got cancer or not.

    It's not just about cachexia either. It's overall health. LCHF will return you to a better overall health. If you return to better overall health, then won't cancer get weaker by comparison? Also, if you don't eat carbs, you'll give less fuel to cancer directly, since most cancers can only use glucose. And then, with better overall health, you'll be able to handle the cancer treatments better. Keep reading the blog and you'll find out just how much LCHF can do for you.

    I'm not an expert so don't take my word for it.

  20. Marie therese
    Where can I find a lchf menu to give me an idea of proportions?
    Reply: #172
  21. Pekka Huttunen
    Marie,
    The reason I like the LCHF diet is that I don't need to worry about proportions. During the first months just keep on eliminating the high carb foods and eat everything else as much as you feel is necessary to feel satisfied. You will notice that if you don't have some fats in your diet, you will not feel right. So, then make sure you have good oils, fats, almonds, etc.
  22. Zepp
  23. acompanhantes rio
    Useful info. Fortunate me I discovered your site by
    chance, and I'm shocked why this twist of fate didn't came about
    earlier! I bookmarked it.
  24. Pasta malzemeleri
    you need to have peer reviewed articel to know how to eat..
    http://pastamalzemeleri.tumblr.com/
  25. Lisa
    My father was a Doctor who specialized in Bariactrics. He advocated the low carb high fat diet in his practice. He lived to be 85 and lived a full and healthy life.

    At my highest weight I was 300 pounds and considering a lap band proceedure. I have Hypothyroidism, Fibromyalgia, Sleep Apnea and I am sure I have metabolic disorder. I lost 60 pounds in 6 months on the low carb high fat diet. I stoped it and gained it almost all back. I was craving sugar, was tired even on thyroid medication it was awful. I got up to 178 pounds again and decided this had to stop. So last week I started the low carb high fat diet again. I have lost 7 pounds in 7 days. It is not all water weight. My shape is even a little changed. Even in just one week. I lost all cravings for sugar and carbs! I have eaten more healthy in this past week than in the last 4 years. I am not hungry. My mind is sharp as can be. I am active again I find it gives me energy. I eat eggs and bacon and ham and canadian bacon and cheeses and tons of vegetables. I found a popcorn with 9 grams of carbs per individual servings and pour lots of butter over it. I made a pizza tonight on a portobello mushroom instead of on crust. It was so filling it felt like I ate an entire pizza myself. I do not feel deprived in any way. I do miss fruit though. I love blood oranges and passed by them in the supermarket. I mean when you crave an orange that can make you fat over buttered popcorn what is that saying? This diet works!

  26. erdoke
    Lisa,
    I don't think that a small fruit treat will do any harm. Add an apple or some berries or the mentioned blood oranges once-twice per day, preferably in between meals. Fruits full of fibers satiate and there is a chance that you find yourself eating less during the regular meals. What I found best to fight cravings is high quality dark chocolate (90-99 %) and mentioned fruits in moderation.
    Another advice which comes from my personal experience: Make sure to include enough fat and don't overeat protein. For most of us first it sounds ridiculous to eat more fat and to stop looking for lean meat, but avoiding 'protein burning' is important. I had been roller coastering between fat and protein based energy sourcing until very recently and it can also cause some non-desirable side effects such as bad breath and imbalanced digestion.
    This calculator might help you find a good estimate of nutrient balance: http://www.phlaunt.com/lowcarb/DietMakeupCalc.php
    Good luck with continuing your health improving journey!
  27. Els
    I have asked the Dutch Heart Foundation on twitter why they don't do research on real prevention of CVD. They spend an awful lot of money on discovering early signs of heart disease and on treatment... but keep advising a high-carb low-fat diet as the way to stay healthy. It makes me angry, because they are hurting people with this advise, family and loved ones among them. People should be able to trust the information they get from their cardiologist and organizations like the Heart Foundation.
  28. Chuck Dickerson
    My presence here started two weeks ago. I'm watching TV and a food book author named Nina Teicholz promoting her tome called "The Big Fat Surprise: Why Butter, Meat and Cheese Belong in a Healthy Diet" This is the most comprehensively researched, engaging, and startling destruction of the concept of the low fat diet and the effects of saturated fat on health ever written. It is researched beyond belief. It chronicles from the very beginnings of recorded health studies how the low fat and cholesterol myths originated and grew into an ubiquitous mantra bordering on a medically religious orthodoxy leading the population of America down a nationwide path of obesity and high carb ill-health where we currently reside! It reads like a murder mystery and I could not put it down.

    It lead me here to LCHF as I looked for a real life pattern of implementation and a new way of eating. It lead my fruit, low fat tortilla chips, low fat dips and snacks, morning cereals, rice, bread, low fat soups and low fat frozen dinners, Smart Balance cooking oil and margarine etc etc. directly to the trash dumpster.

    At 6'3" 325 lbs, eating as much bacon and sausage and eggs as I want for breakfast, beef (ground or otherwise) and roasted chickens with skin, cheese, butter on as many vegetables or meats as I like, suddenly I am never hungry and losing weight at the rate of 3-5 pounds a week on average. Holy Moly! I'm losing weight on a lifestyle eating change rather than a diet. The best part is it's free. The 94 pounds I lost through the Lindora weight loss clinic in CA 2.5 years ago cost me $1300 and I gained it all back in two years! ...Oh yeah it was a low carb regimen including many of their own low carb foods and snacks for sale, of course. What was missing of course was the high fat component. The long term maintenance foods they try to inculcate remained so foreign to my enjoyment of food that I could not follow that regimen. Trying to wing it on every low fat and "sugarless" concoction marketed to us by every food manufacturer in America led me right back down the fat road to ruin. EATING FAT DOES NOT CAUSE FAT, IT DOES THE OPPOSITE! Who knew?

  29. Linds
    Heartburn.

    I've only very occasionally suffered from heartburn throughout my life. The times I happened to get it was after continuous eating of take-outs, rich sugary foods and excessive drinking (duh) but even then one dose of ant-acid sorted it out in no time.

    When I started a low carb. diet 3 weeks ago I started getting heartburn pain after 3 or 4 days and it continued on and off, mostly on, for the following two weeks. Clearly something was not right with my diet. Turns out what was wrong was I was eating low carb. and low fat. Quite literally the day I introduced high fat into my diet the heartburn stopped.

    I am finding it a hard mental adjustment that eating so much fat is a good thing but I do love it!

  30. Michael
    I had a question for the Diet Doctor. I have been doing the LCHF program for a few months now, shifting from 5:2 fasting and traditional low carb. Using BPC with LCHF now. All and all I am down about 75lbs, and figure I have another 30 to go for goal weight. Losing about 2 lbs a week.

    Recently I had lab tests done for a life insurance policy, and all my numbers looked really good except for my Total Cholesterol (289) and my LDL(200). My HDL looks great(75) as well my LDL/HDL ratio (2.68). All my other numbers are great and I feel good. I should clarify that I have always had higher numbers for these 2 readings, but never this high, even though I have lost alot of weight since my last test.

    I am concerned that all the fat I am consuming is causing these elevated cholesterol numbers and increasing my risk of heart disease, but also thought I read somewhere that LDL might be increased when on LCHF and is a false positive. I also understand that there are other tests that may need to be conducted to get a more accurate picture (LDL Particle size?). Also even read somewhere that is may also just be a biproduct of my rapid fat loss since the fat is mobilizing in my blood stream, and LDL can stablize once you go to maintenance mode and have lost the weight

    I have asked my doctor his opinion but afraid he may not understand LCHF or benefits of ketogenic diets. I am afraid he's going to want to put me on statins, which I don't want to do.

    Can you provide any insight to understanding these cholesterol numbers.

    Replies: #181, #182
  31. Zepp
    You got it right.. its more complicated then a simple lipid panel!

    First, 289/75= 3,8

    Its the best risk evaluation on a standard lipid panel.. it should be 6 or less, better if its 5 or less. very good if its 4 or less..

    You got very high HDL!

    APOb/APOa1, or NMR is the new golden standard for accessing risk of future CVD!

  32. Zepp
    And Im not Dr Eenfeldt but answer anyway.

    Here you can read and learn more.. frome a cardiologist!

    http://www.docsopinion.com/2013/12/15/10-pitfalls-of-using-ldl-choles...

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