Paleo Diet versus Mediterranean Diet

A 2010 study (via Whole Health Source) compared a Paleo diet with a Mediterranean diet. For twelve weeks, twenty-nine volunteers could eat as much as they wanted, whenever they wanted. Half ate Paleo (“lean meat, fish, fruit, vegetables, root vegetables, eggs, and nuts”), half Mediterranean (“whole grains, low-fat dairy products, vegetables, fruit, fish, and oils and margarines”).

The main result was that the Paleo food was “more satiating per calorie”. The Paleo eaters ate less but no more often than Mediterranean eaters. The paper does not report weight loss. (See an earlier report of the same experiment for that.)

I suspect the Paleo diet was less familiar than the Mediterranean diet (of course I can’t be sure from the descriptions). My theory of weight control says familiarity matters: less-familiar food pushes your set point lower than familiar food because its smell-calorie associations are weaker. The smells of less-familiar food is less associated with calories than the smells of more familiar food. With a lower set point, you will need less food to feel full.

If familiarity matters, this causes big problems for clinical studies. It means that short-term results (e.g., after 6 months) may be quite different than long-term results (e.g., after 2 years) — and most clinical trials last about six months. Short term, says my theory, any new food will cause weight loss. Indeed, a wide range of diets that cause dieters to eat new foods, such as the cabbage soup diet, cause short-term weight loss. Over the long term, however, the new foods become familiar and, according to my theory, the set point goes back up as the new smell-calorie associations are learned. Indeed, on most diets there is great long-term weight regain. If familiarity matters, we need data sets lasting a long time (e.g., nine or ten years) to understand weight control. Such data sets allow enough time for the chosen diets to become familiar so that (a) the diets being compared are equal in familiarity and (b) we can see their long-term effects — which may easily be different from their short-term effects.

Thanks to Steve Hansen.

9 Responses to “Paleo Diet versus Mediterranean Diet”

  1. Peggy The Primal Parent Says:

    Your theory supports the idea to eat local, in season food. If people eat whole foods (which itself encourages weight loss) and rotate foods every three months or so, they would never gain weight because every three months they would be eating new foods, hence causing weight loss! Cool.

  2. R.K. Says:

    Puzzling, then, how an experiment could radically change the subjects diet and yet weight stays stable. From http://wholehealthsource.blogspot.com/2011/05/food-reward-dominant-factor-in-obesity.html :

    “The first thing they report is what happened when they fed two lean people using the machine, for 16 or 9 days. Both of them maintained their typical calorie intake (~3,075 and ~4,430 kcal per day) and maintained a very stable weight during this period.”

  3. bjk Says:

    If I eat a monotonous, non-rewarding diet, does that counteract the effects of familiarity? Because I can lose weight eating the same thing every day, it solves the problem of what to eat, which is half the problem.

  4. Seth Roberts Says:

    I’m not sure what you mean by a “non-rewarding” diet. But, yes, if you eat bland foods you will lose weight. Cabanac and his colleagues found that. Foods with weak smells do not form strong smell-calorie associations.

  5. Seth Roberts Says:

    I explain those results by assuming that when the set point is already low, changing the diet doesn’t lower it. Only when the set point has been raised by smell-calorie associations do you get the loss-followed-by-regain effect.

  6. Seth Roberts Says:

    The Sensa system of Alan Hirsch changes the flavorants (sprinkled on food) every month. So perhaps there is significant smell-calorie learning within a month.

  7. Robbo Says:

    I don’t think this is a Mediterranean diet since it contains ” low-fat dairy products and margarines”. I would also question what oils were included (only olive oil = Mediterranean)

    The hilarious thing is, by travestying the Med diet, the study owners probably thought they were improving it.

  8. Carlos Says:

    One thing that bothers me about this studies is how often they make up the “mediterranean diet” Being from Spain I can asure you that the proposed diet does no resembles our traditional food. whole cereals were unheard of until a decade or so. Low.-fat dairy was a niche product and margarine was started to being use at the begining of the 90′s (and because it spreads easier on bread) Another thing that always bothers me is how devoid of legumes are these “so called” mediterranean diets. I don’t know about the rest of the mediterranean contries but in spain legumes are a staple food.

  9. Nick Says:

    I agree that novelty has additional effects outside of the traditional norm. Usually not controlled for in studies. I also find this effect in other areas like excersize and pointless to state the obvious “learning”.

    Id like Seth to comment on the effects Of chronic novelty as applied to food or anything else for that matter.

    Would this cancel out the “set point” mechanism in the long run and force the body to seek an alternative. What would that alternative be?