Short-Term Effects of a Paleolithic Diet in Healthy Medical Students

Stockholm Palace

Swedish investigators at Karolinska Institutet found diminished weight, body mass index, blood pressure, and waist circumference in 14 healthy medical students eating a paleo diet for three weeks.

Published in 2008, this seems to be one of the seminal scientific studies of the paleo diet in modern Europeans.

Their version of the paleo diet:

  • Allowed ad lib: All fresh or frozen fruits, berries and vegetables except legumes, canned tomatoes w/o additives, fresh or frozen unsalted fish and seafood, fresh or frozen unsalted lean meats and minced meat, unsalted nuts (except peanuts – a  legume), fresh squeezed lemon or lime juice (as dressing), flaxseed or rapeseed oil (as dressing), coffee and tea (w/o sugar, milk, honey, or cream), all salt-free spices.
  • Allowed but with major restrictions: dried fruit, salted seafood, fat meat, potatoes (two medium-sized per day), honey, cured meats
  • Prohibited: all milk and dairy products, all grain products (including corn and rice), all legumes, canned food except tomatoes, candy, ice cream, soft drinks, juices, syrups, alcohol, sugar, and salt

What Did They Find After Three Weeks?

  • Average weight dropped from 65.2 kg (144 lb) to 62.9 (139 lb) 
  • Average body mass index fell from 22.2 to 21.4
  • Average waist circumference decreased from 74.3 cm (29.25″) to 72.6 cm (28.58″) 
  • Average systolic blood pressure fell from 110 to 104 mmHg
  • plasminogen activator inhibitor-1 decreased from 5.0 kIE/l to 2.8 kIE/l
  • All of these changes were statistically significant

The researchers looked at a number of other blood tests and didn’t find any significant differences. 

Five men and nine women completed the study.  Of the 20 who originally signed up, one could not fulfill the diet, three became ill (no details), two failed to show up.

So What?

That’s a remarkable weight loss over just three weeks for slender people eating ad lib.

The study authors concluded that these paleo diet-induced changes could reduce risk for cardiovascular disease.  They called for a larger study with a control group.  (If it’s been done, I haven’t found it yet.)

Sounds reasonable.

Steve Parker, M.D.

PS: You’d think they would have said more about the three participants who got sick, rather than leave us wondering if the diet made them ill.

Reference:  Österdahl, M; Kocturk, T; Koochek, A;Wändell, PE.  Effects of a short-term intervention with a paleolithic diet in healthy volunteers.  European Journal of Clinical Nutrition, 62 (2008): 682-685.

6 responses to “Short-Term Effects of a Paleolithic Diet in Healthy Medical Students

  1. So your comment was that the diet produced “remarkable weight loss” … Really?

    My comment would be that the diet was a massive failure, if 60 percent of the participants dropped out in just three weeks.

  2. Hey, Jim. You caught one of my rare mistakes! Thank God I hadn’t emptied my trashcan yet so I could go back to the source.
    In the original post I wrote “Five men and three women completed the study.” Actually, five men and 9 women completed it; the drop-out rate was 33%. It’s probably not fair to include the two no-shows (after they signed up) in the drop-out rate, but I did.
    This was not a weight-loss study. It was “let’s do this and see what happens” study. These med students were pretty light at the outset; One might interpret the weight loss as an adverse effect of the diet.
    I went back and corrected my mistake in the original post.

  3. According to the abstract, energy intake was reduced by 36%.

    I can’t help but think that this is a result of (unintentional) carbohydrate restriction.

    That’s the thing about studying Paleo diets. While not necessarily low-carb in theory, they tend to be low-carb in practice. Hard to tell if it’s the quantity or the quality of carbs that produce the results, or even the inclusion/exclusion of some other foods.

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