Study shows a ‘primal’ diet can bring rapid weight loss and health benefits

On Monday I started a blog about the artificial sweetener aspartame with a reference to my preference for a diet rich in natural, unprocessed foods. Such a diet might be described in various ways including a ‘hunter-gatherer’, ‘caveman’ or ‘paleolithic’ diet. However such a diet is described, the aim is the same: to feed the body with foods that have been long-time elements of the human diet. This way, in theory at least, we’ll be giving the body the foods it has evolved to eat, and are therefore the best for it.

My belief is that there’s an abundance of evidence that going back to basics with our diet is the way forward for individuals wishing to optimise their health. And a recently-published study seems to have added to this body of evidence.

The study in question tested the impact of a ‘paleolithic’ diet in 20 men and women aged 20-40 [1]. The dietary instruction given to participants of this study were as follows:

Foods permitted in unlimited quantities:
All fresh or frozen fruits, berries and vegetables except legumes, canned tomatoes without additives except for citric acid, fresh or frozen unsalted fish and seafood, fresh or frozen unsalted lean meats and minced meat, unsalted nuts (except peanuts), fresh squeezed lemon or lime juice (as dressing), flaxseed or rapeseed oil (as dressing), coffee and tea (without sugar, honey, milk or cream), all salt-free spices.

Food permitted in limited quantity:
Dried fruit (2 days/week), salted seafood (one meal/week), fat meat (one meal/week), potatoes (two medium sized/day), honey (used in marinade once/week), cured meats (as entrée once/week), mineral water (only when drinkable tap water was not available).

Prohibited food:
All milk and dairy products, all grain products (including maize and rice), all legumes (beans, lentils, peanuts), processed meats (e.g. sausages, pâtés), canned food (except tomatoes, see above) and all forms of confectionery, ice cream, sorbet, soft drinks, juices, syrups, liquor, sugar and salt.

Individuals were instructed to eat this diet for 3 weeks. 14 of the 20 individuals who volunteered for the study actually finished it.

Compared to what they had been eating previously, eating the paleolithic diet led to a significant reduction in overall food intake (about 900 calories less per day on average). Fat consumption reduced by about 20 g per day, but more notably, I think, is that carbohydrate consumption fell by 177 g per day on average (it has been previously been noted that primitive diets tends to be lower in carbohydrate than a typical Western diet [2]). The paleolithic diet also was higher in vitamin C and lower in sodium than the baseline diet.

After just 3 weeks, there was significant change in a number of measurements. Most notably, these were:

An average weight reduction of 2.3 kg (about 5 lbs)

An average reduction in waist circumference of 1.5 cm (about ½ inch)

An average reduction in systolic blood pressure (the higher of the two blood pressure readings) of 3 mmHg (mm of mercury)

A 72 per cent reduction in the levels of a substance known as plasminogen activator inhibitor-1 (this would be expected to reduce the clotting tendency of the blood, which might translate into a reduced risk of heart attack and stroke)

This study is somewhat hampered by the absence of a control group (a group eating a diet against which the paleolithic diet could be compared) and its small scale (just 14 people). However, its results mirror very much what I find in practice: when individuals move their diet in a primal direction, they very often end up eating less quite naturally, and also will tend to shed weight with relative ease as a result. Also, the results from such a dietary change, in my experience, can be quick (as this study demonstrates).

Longer-term studies of a paleolithic diet would be nice to have. However, in their absence, all we have to go on is our experience. Here again, mine are generally positive. Because eating this sort of diet usually allows individuals to lose excess weight without hunger, it is something that individuals tend to find sustainable in the long term, which obviously ups the chances of good results in the long term too. Generally speaking, I reckon going back to our nutritional past is the way forward for those seeking to lose weight and optimise their health.


1. �-sterdahl M, et al. Effects of a short-term intervention with a paleolithic diet in healthy volunteers. European Journal of Clinical Nutrition 2008;62:682″685

2. Cordain L, et al. Plant-animal subsistence ratios and macronutrient energy estimations in worldwide hunter-gatherer diets. Am J Clin Nutr. 2000;71(3):682-92

27 Responses to Study shows a ‘primal’ diet can bring rapid weight loss and health benefits

  1. Chris 9 May 2008 at 11:32 am #

    Hi there

    I too am a fan of the paleo diet, but having looked at this study I was a bit annoyed that it didn’t look well designed – e.g. perhaps the improvements were due to a reduction in calories consumed irrespective of the composition of the diet?

  2. Dr John Briffa 9 May 2008 at 11:37 am #

    I see your point Chris – but I actually liked the fact that the ‘primal’ foods used as the basis for the diet were allowed to be eaten freely, and the fact that this seems to have led to a natural reduction in the calorific value of the food eaten. I think this study demonstrates what I usually find in practice: when individuals concentrate on the quality of their diets, they need to consider the quantity they eat far less.

  3. Daisy 9 May 2008 at 1:06 pm #

    Aren’t legumes supposed to be healthy? I don’t know what I’d do without my weekly lentil/chick pea/pinto bean fix!

  4. George 9 May 2008 at 2:17 pm #

    I have been following the paleo diet for a few years now.
    I was interested to see that potatoes had been included in this study, is this a grey area? as some nutritional writers include potatoes in the paleo diet and some are firmly against it.
    I am very interested to know where potatoes come in terms of a healthy carb? Are they healthier than Brown rice or Lentils, beans etc.


  5. myrena 9 May 2008 at 2:27 pm #

    I am a bit surprised that people were supposed to eat l e a n meat – this does not correspond to what is now of paleo-nutrition at all. People depended on eating fat for survival – lean meat was only eaten when nothing else was available.

  6. Vivian 9 May 2008 at 3:52 pm #

    I’ve been following a paleo-type diet for 2 years now. The only real differences between my eating habits and those in the study: I eat no potatoes; I don’t concentrate on lean meat, but rather on pastured, organic meat of any type, no matter how fatty it might be; I do sneak in the occasional piece of hard cheese (every girl’s gotta have a vice). The study was silent on wine – but I also try to have a small glass or red most days of the week.

    My experience mirrors the results of the study. My hunger was considerably reduced, almost immediately. Willpower was no longer an issue, because now I am simply not hungry between meals. As a diabetic, this eating plan gives me great blood sugar control, and it ended my prescription high-blood pressure meds, lowered my triglycerides substantially and raised my HDL. My doctor has been astounded (although, unfortunately, not that interested in how the change happened, just that it did).

    The upside of this approach to eating is that it is psychologically easy to maintain, and 2 years after my 70 pound weight loss, I haven’t gained a pound back – and I’m not denying my hunger in order to maintain the weight loss. I’m simply not hungry (and when I do eat, food seems to taste a lot better! Maybe because I’m paying more attention to it.). My husband joined me a few months after I started, after seeing the ease of my success, and he hasn’t looked back either.

    There is a downside, though not from a health point of view: This is an expensive, time-consuming way to eat. We must shop more, plan more, cook more, pay more. It’s a more than worthwhile tradeoff for those who can afford the time, effort and money, however I fear it’s not a realistic approach for everyone.

  7. Pauline 9 May 2008 at 4:47 pm #

    My husband Rob is 6ft tall, weighs 138 lbs, and has been eating the paleo for several years. Before the change in diet he was 205 lbs and his blood pressure was 160 over 105. At the most recent reading it showed 135 over 76. Like Vivian he eats the odd piece of cheese, usually unpasteurised Camembert and a nightly glass of red wine or three. Perhaps I should add that he walks the dogs for at least an hour a day, usually covering 4 miles or so.

  8. Sarah 9 May 2008 at 5:01 pm #

    This is pretty much how I eat, too. No potatoes, though — my blood glucose doesn’t react well to them. And I will indulge in a little cheese every once in a while. I was ovo-lacto vegetarian for 20+ years, and my current physician (who encourages the paleo way of eating for ALL her patients) believes the high carb/low fat way I ate for all those years contributed to my hypothyroidism (a lot of soy!) and may have played at factor in developing diabetes. I also gained weight — something that hadn’t been an issue before adopting the high carb/low fat way of eating.

    I had no trouble loosing the weight I needed to lose once I switched to a paleo-centered way of eating. The diabetes “beast” is under control, with my a1c ranging between 5.0% and 5.2%. Lipid profile is very good, with the exception of HDL which is still low and has my physician and me stumped.

    So, I’m a big fan of paleo eating and find I don’t even miss the pasta, bread, etc. that I used to make the centerpiece of my meals.

  9. Hilda 9 May 2008 at 5:11 pm #

    I too agree with the Paleo diet but , while trying not to be unpleasant, be careful not to think of wine as a sort of health food. One person said ‘I try to….drink wine’. Alcohol is a poison which has to be detoxified in the liver. THe antioxidants come from the grapes so just eat black grapes.

    How would be get wine in the stone age?

  10. Chris Highcock 9 May 2008 at 5:28 pm #

    I take yoru point John.

    By the way – notice how the establishment do not like this study:

  11. James H 9 May 2008 at 5:32 pm #

    Surely for a Paleo diet, how the meat animal is raised needs to be considered. For example battery farmed chicken – fast growing, fat due to lack of movement and feed on grain. Surely that can’t be considered Paleo ?

  12. Dr John Briffa 9 May 2008 at 5:48 pm #

    Chris – thanks for the link.
    I love this: describing a diet similar to the one we’ve been eating for the vast majority of our time on this planet as a ‘fad’.

    Plus, look at how the author suggests: “More importantly, a high dropout rate suggests that there is something about the diet that makes six out of 20 people disinclined to complete a three-week study.”

    It clearly states in the paper what the reason for the dropouts was though: “One subject did not start, one missed the laboratory test, four broke the study, three because of illness and one could not fulfil the diet.”

    So, did the author of this piece not read the study or just ignore what was written? Well, you won’t be able to ask the author because he/she remains nameless.

  13. Neil 9 May 2008 at 7:19 pm #

    I am not sure that a paleo diet would include flaxseed and rapeseed oil, even as dressing! or that fatty meat would be excluded for 6 days out of 7.

    Sounds like the study authors are part of the “Sat Fat is bad” brigade!

    Still, at least a step in the right direction

  14. Daisy 9 May 2008 at 9:18 pm #

    Is this is a diet you have to follow 100%? Because although convincing, it also looks pretty hard to follow. Do paleo people ever go to restos?
    But most urgently, can you answer my question on pulses? In previous posts you have extolled their virtues, and yet they’re forbidden in this diet.

  15. Dr John Briffa 10 May 2008 at 6:32 am #

    The reason that pulses are forbidden on the paleo diet is not necessarily on health grounds, but on the basis that they’re not ‘paleo’ foods.

  16. Pauline 10 May 2008 at 3:18 pm #

    I think it is a mistake to be a slave to any particular diet, although acknowledging that wheat and dairy have been introduced into the human food chain only comparatively recently I find no difficulty in recognizing that they are not necessary and may even be deleterious to the maintenance of optimum health. If Hilda eschews the drinking of wine then I fully accept her right to point out it’s dangers although for myself I prefer to gain some comfort from knowing that a French lady who lived to the great age of 122years actually imbibed upon a daily basis whilst also enjoying a cigarette or two!

  17. Rose (Morris) 12 May 2008 at 1:54 pm #

    What about eggs? And what about cold-compressed olive oil, and, actually, other oils such as sesame and avocado?
    Thanks for terrifically interesting stuff on health!!!

  18. New Zealand Honey Shop 13 May 2008 at 10:43 pm #

    At least you point out the limitations of this particular study, i,e the small numbers. It always amazes me when these types of limitations are omitted from reports /news releases for most studies.

    There is another point I’d be keen to find out more about when it comes to diet issues, and that is the way that we eat our food. With many modern ‘meals’ people tend to scoff them down. I’ve recently seen a comment in a book that if we chew our food properly, and equally, concentrate with our minds / thoughts on what we are eating, the flavour and texture of the food, and enjoying it (as opposed to thinking about work, whats on tv etc etc) then that is also very beneficial to us. I’m guessing that it’s how our ancestors probably ate – concentrating on the task at hand and the process of eating. Would you know of any studies / evidence that would support this? Would it be something to promote alongside the contents of suggested diets?

  19. Anna 15 May 2008 at 6:17 pm #

    I tend to serve a somewhat paleo-inspired diet to my family, though we do include dairy fairly frequently. Most of the time, I do source our meat and dairy from pastured sources, not grainfed or from feedlots. Most of our dairy consumption is raw and whole, though (even the fluid milk) and much of it is fermented /cultured (cheese, yogurt, etc.) and some of it is home-prepared (fresh cheeses, cultured dairy). So while I don’t stick hard and fast to all paleo details, but it is extremely helpful to use a “paleo lens” to decide which foods to consume regularly, which forms are more like those found in nature, and which to limit or eliminate.

    I also find the “fad” label ironic when applied to paleo diets. Regarding wine, since many fermentation is a process that occurs in nature even without human intervention, and no doubt paleo humans chanced upon and perhaps sought out naturally fermented foods, I think it is reasonable to include some wine if one wishes. I doubt one “needs” to include it, though. I am finding that maintaining my weight is much easier without a glass of wine with dinner, though. I now tend to limit wine to once or twice a week, or even less frequently (my husband doesn’t drink alcohol very frequently because he often does some work-related writing in the evening). Additionally a glass of wine at home with dinner induces too much sleepiness too early in the evening for me now, unless there is enough of a social atmosphere.

  20. Malcolm 16 May 2008 at 3:27 pm #

    The paleo diet seems spot on to me, John, and I’m doing my best to follow it. However, next year I plan to cycle Land’s End to John O’Groats. How can I ensure that my muscles will have sufficient glycogen stores to ride 100 plus miles per day without eating loads of cereal-based carbs?

  21. Neil 18 May 2008 at 10:09 am #

    surely on a paleo type diet, you’ll be burning fat as your basis for fuel for energy??

    Stephen Phinney (I think) has worked with cycling and low-carb diets in the US, try googling his name.

  22. Malcolm 23 May 2008 at 1:53 pm #

    Thanks for that, Neil. I’ll google him.

  23. Anna (b) 4 February 2009 at 2:34 pm #

    Have there been any studies into the usefulness of a paleo/primal diet for controlling the symptoms of IBS? and secondly

    Where do the proponents of such a diet stand on the consumption of alcohol?

  24. Anne 27 April 2011 at 8:03 pm #

    I inject insulin daily. How will that affect my sucess with the primal diet?


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