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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150 Comments

  1. I fully agree that low carb, high protein diets are the way to lose weight. I can't believe there are still other bloggers disagreeing and saying that low carbs are not the way to go.. For privacy reasons I won't mention their names. But for anybody who wants to lose weight and are reading this comment, understand this - low carb works.
  2. es
    >>>low carb, high protein diets are the way to lose weight

    Alvin, there is a difference between Low carb high protein and low carb high fat diets.

    This page focuses on the effectiveness of Low carb high fat. Low carb high protein diets are not as healthy or effective for weight loss.

  3. Just
    What are the long-term effects of eating this way? The first article does not mention it. If it's becoming more healthier, then please direct me to a systematic review or a collection (not just one) peer-reviewed articles.

    Thanks

    Replies: #104, #105
  4. Zepp
    Well if you need to have peer reviewed articel to know how to eat.. stop at ones to eat SAD, becuse there is no such on that diet!

    And then you have to find your own way.. LCHF/Paleo is another way to eat.. but its only a hypotese, that its healty to eat real food full of nutrients!

  5. es
    What are the long-term effects of eating this way? The first article does not mention it.

    First, there is a lot of good science on this page, all peer-reviewed, why stop at the first?

    Second, we know as much, if not more, about the long term effects of a LCHF diet as we do about the long term effects of calorie restricted or low fat diets.

    Third, what we know (see the studies above) is that up to 2 years there are no ill effects of LCHF and there are continued improvements in risk factors for chronic disease.

    Fourth, it's not reasonable to assume that after 2 years risk factors for chronic disease suddenly reverse or that new unknown risks appear.

    Fifth, we do know the long term effects on health of the high carb Standard American Diet (SAD). It leads to obesity, low HDL, high Triglycerides, high small LDL, high blood pressure, metabolic syndrome and higher risks for Type II diabetes and fatty liver disease.

    ES

  6. 20 comments removed
  7. eddacker
    It seems the spam-bot has found this thread, in such a perfectly manner of writing and cannot help but singing your praises.

    So glad it is just this toic and not every one on the D-docs site.

    please do not respond as spam-bots get bored and go away.

    eventually

    Reply: #128
  8. 1 comment removed
  9. Sophie
    Spamming: I have been systematically reporting spam posts.

    PLease do the same by clicking on the exclamaiton mark that appears when you slide your cursor left of the number on the right of the comment.

    Thx!

  10. Zepp
    A new professor that not scared of fat!

    Dietary Fats and Health: Dietary Recommendations in the Context of Scientific Evidence

    "Saturated fats are benign with regard to inflammatory effects, as are the MUFAs. The meager effect that saturated fats have on serum cholesterol levels when modest but adequate amounts of polyunsaturated oils are included in the diet, and the lack of any clear evidence that saturated fats are promoting any of the conditions that can be attributed to PUFA makes one wonder how saturated fats got such a bad reputation in the health literature. The influence of dietary fats on serum cholesterol has been overstated, and a physiological mechanism for saturated fats causing heart disease is still missing.

    Various aldehydes produced in the oxidation of PUFAs, as well as sugars, are known to initiate or augment several diseases, such as cancer, inflammation, asthma, type 2 diabetes, atherosclerosis, and endothelial dysfunction. Saturated fats per se may not be responsible for many of the adverse health effects with which they have been associated; instead, oxidation of PUFAs in those foods may be the cause of any associations that have been found. Consequently, the dietary recommendations to restrict saturated fats in the diet should be revised to reflect differences in handling before consumption, e.g., dairy fats are generally not heated to high temperatures. It is time to reevaluate the dietary recommendations that focus on lowering serum cholesterol and to use a more holistic approach to dietary policy."

    http://advances.nutrition.org/content/4/3/294.full

  11. Michael
    I'm new to the site and finding a lot of very interesting information here! At any rate, just thought I'd share yet another study that supports a high fat diet...

    "Low-fat diets have not been shown in any rigorous way to be helpful, and they are also very hard for patients to maintain — a reality borne out in the new study, said Dr. Steven E. Nissen, chairman of the department of cardiovascular medicine at the Cleveland Clinic Foundation."

    Full Article:
    http://www.nejm.org/doi/full/10.1056/NEJMoa1200303?query=featured_hom...

  12. 1 comment removed
  13. Lars Avemarie
    Dear Diet Doctor

    I has been brought to my attention (by Alan Aragon) than of the 18 studies, in 17 of them, the diet was not match for protein intake. In all of the 17 studies the protein intake was higher in the low-carb diets. The amount of protein was 46% higher in the low-carb diets.

    And given proteins great effect on satiety and LBM, this makes it an uneven comparison, and you conclution “RCTs showing significantly more weight loss with low carb diets” problematic.

    Regards, Lars

    Reply: #133
  14. Zepp
    I dont know if you is critisising or if you are pointing to that amino acids are essentiall.. and that low consumtion of protein is not a good idea for losing fat weight!

    I looked at some of the studies, and it seems to me, that they was eating to little proteins.. and calories, in the begining.. but those how get on a low carb diet seems to adjusted it to more normal amounts.. about 20E%.

    And that could be an answer to why a normal high carb traditional diet not som good.. one lose fat free mass and gain fat weight!

    Becuse.. even if protein is a macronutrient.. its mostly a boulding stone.. and fat or carbs is almoste pure energy.

    And one need all the muscles becuse its those how supose to burn the extra fatstores.

    Mayby we should rename to LCHFNP?

  15. Natasha
    Dear Diet Doctor,

    Is having LCHF meals still fine for you health if you are not in ketosis or ever planning to go into ketosis?

    My husband has started on a LCHF diet and I would like to know if it is ok for myself and my small children to have same evening meal with him in the evening (LCHF) when we are eating other things that are HC at other times (bananas, apples, oats etc).

    If you are not in ketosis, what happens to the fat you eat when you have a high fat meal?

    Reply: #135
  16. Zepp
    Yes.. LCHF supose to be healty food.. and for those needed to get in ketosis, those have to cut out more carbs then others.

    You burn what you eat.. if you eat high fat one burn high fat!

    Ketosis means that you eating less carbs then your bodys emediate demand of glucose.. then i make some in the liver and make ketones altso to replace some glucose!

    Ketosis (ketolysis) is not the major fatburning capasity.. its betaoxidation, where fat is broken down to be used in the Citric Acid cycle!

    Your muscles burn moste of the fats, the brain and heart is very fond of ketones!

    The brain can only use glucose or ketones.

  17. ersin
    lvhf allowes dairy and limits fruits, while paleo calim the opposite... why is that?

    if all carbs are sugar, than eating a piece of bread intead of lots of veggies has the same effects?

    should we extract the fiber count from the carb count?

  18. Zepp
    Paleo is about to eat like our ancestors did, in Paleoliticum!

    Its about that they didnt have our modern diseses.. how often is food related.

    LCHF is broader, its more about to lower glycemic load, and one can eat Paleo and some even is vegetarians!

    Yes, one slice of bread give you as much carbs/blood sugar as a lot of veggies.. but then, what is moste healty?

    Its about if one have to lower glycemic load.. if you eat a slice of bread or some, then there is no more rom for veggies!

    Yes one should extract the fibers, they are eighter not digested or converted to short fatty acids in your guts.

  19. Ersin
    ok thanks
    so what THE Max he of carbs to loose fat? and to maintain?
    Reply: #139
  20. Zepp
    You know, there are no such magical numbers.. there are only your magical body, and you have to try it out!

    But one says that a ketogenic diet starts about 100 net carbs a day, try to hit about 50 or less in the transitation period!

    Then there are rom for a lot of non starchy veggies, some diarys, berrys, nuts and even low carb tubers!

    What happens is that you going to get glucose shortige, feels bad for a week or so, then you force your body to use fat as predominant fuel!

    And if it goes as one hopes, then your body use some of your body fat as fuel inbetwen meals, your apetite gets lower, one eat less or often fewer meals.

  21. ersin
    what do you think about sesame seed butter, or tahini, instead of almond butter?
    it does have lots of fats, some carbs and lots of fibers?

    what about whey protein powders?

  22. Zepp
    Sesame seed is a lot of fat, but the wrong form of it.. PUFA and Omega-6.. us it on special ocassions.. and eat a lot of fish as antidot, or take Omega-3 as EPA/DHA!

    http://www.fineli.fi/food.php?foodid=385&lang=en

    Try coconut butter instead!

    About whey powder.. eat chees insted.. or preferbly some meat.. try to eat as much real food.. its best in the long turn, perticuly if its home coocked!

  23. Eddie
    I have not had time to go through the above links to the papers. Do any of them refer to the body of research on fructose converting directly to fat and into the bloodstream, and bypassing in effect the bodies 'calorie counter'? This is given as the reason why we eat 'western food' and still feel hungry, even though we have consumed more calories than we need to feel sated, = hard to control weight gain!
    If not, search on the above for research on this area. An Australian author has compiled much of this evidence, as well as that of the dangers of processed seed oils.
    We now use dextrose instead of cane sugar (ie just about all forms of processed and added sugar), and avoid all 'sugary' foods. What a change - you lose the sweet-tooth AND you don't get that 'furry teeth' feeling. I also notice I am not as tired since removing processed seed-oils from my diet. (Still researching the grain side - thats why I'm here)
    Reply: #144
  24. Zepp
    There are a lot of post of Robert Lustigs crusade against fructose here.. here is one.

    http://www.dietdoctor.com/dr-robert-fat-chance-lustig-on-the-colbert-...

    And from William Davis about wheat.

    http://www.dietdoctor.com/dr-william-wheat-belly-davis-on-the-dr-oz-show

  25. ES
    Do any of them refer to the body of research on fructose converting directly to fat and into the bloodstream, and bypassing in effect the bodies 'calorie counter'?

    The body doesn't have a "calorie counter." Instead it has a pancreas which produces either insulin or glucagon in response to blood sugar.

    When carbs generally make up a small proportion of the diet, varying seasonally, that was all the calorie counting we needed. Our metabolism is tuned to a low-carb diet.

    It's only when carbs are so out of balance (50 to 65% of calories) that our metabolism gets deranged and we become overweight and obese.

  26. Fred
    This Swedish study found that the Low Carb, High Fat diet is bad for you and bad cholestorol levels go up and good one's go down.
    http://www.theatlantic.com/health/archive/2012/06/time-to-retire-the-...
  27. Ted Hutchinson
    In reply to Fred comment 145
    Dr John Briffa posted on this study at the time
    Shocking Swedish ‘science’ by Dr John Briffa

    as did Denise Minger on Marks Daily Apple.

    Is It Time to Retire the Low-Carb Diet “Fad”?

  28. ken
    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...
    Reply: #159
  29. Eddie
    The body doesn't have a "calorie counter." Instead...(Thanks to ES)
    Yes - it needs more detail - here is how I read this:
    - Cholecystokinin (CCK) - polypeptide hormone produced principally by the small intestine in response to the presence of fats - "An accumulation of CCK in the bloodstream signals to our appetitie-control system that we've had enough to eat" -I believe the author is referring to the responses of the rest ofthe body to release of CCK
    - Insulin - but does not respond to fructose! - which immediately convert to triglycerides. In short, stack on 'fat' calories by consuming fructose, yet you do not feel your appetite is satiated
    - Leptin - "The more fat cells we have the more leptin is released..it acts as a kind of long-term fuel-gauge for our appetite control system"
    - Ghrelin - released by stomach - temporarily reverses the effect of leptin - causes stomach rumbling
    The author summarises the operation of these systems as an "appetite control system", which is bypassed by fructose consumption, and continuous consumption of sufficient fructose will cause continuous circulation of triglycerides in the blood-stream which reduces the effect of the 'stop eating now' effect of the other hormones.
    I can attest that after cutting out all concentrated fructose sources from my diet, my appetite certainly became SHARP! ie strong pangs at meal-o'clock which go as soon as I have consumed the first few mouthfuls, then a more subtle sense of 'fullness' which I guess is my body saying 'enough', toward the end of the meal. No feeling for in-between meal snacks, no sugar cravings.

    ...prove you can eat any food in calories above your body's maintenance and lose weight...(Thanks to Ken)
    Yes! As you can see, my above transcription explains how our ability to sense the calories we consume is destroyed by the excessive amounts of fructose we may consume in processed foods.

  30. Eddie
    To Ted;
    Yes - I had a quick look at the Swedish connection in that article - would it be true to say that for the population majority there is high intake of
    a) fructose = loss of appetite control = increased calorific intake (just look at all the sweetened alcoholic drinks they export)
    b) polyunsturated fats = increased *oxidised* LDL - this being the real culprit in formation of artherosclerotic lesions (sorry - just do a search for papers on 'oxidised LDL' - loads info)
  31. ken
    Eddie it has never been proven ever, even Atkins finally admitted if he told people to eat fat and drop cals they would eat less.....funny ,everyone agrees 3500 cals make a lb of fat but it does take -3500 cals to lose fat..
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