Paleo Diet and Paleolithic Diet Questions & Answers

Question

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The New York Times has an article on the latest out of the Nurses’ Health Study, Nurses’ Health Study II and the Health Professionals Follow-up Study. Some of the findings predictive of weight gain are in line with Paleo; others are not:

The foods that contributed to the greatest weight gain were not surprising. French fries led the list: Increased consumption of this food alone was linked to an average weight gain of 3.4 pounds in each four-year period. Other important contributors were potato chips (1.7 pounds), sugar-sweetened drinks (1 pound), red meats and processed meats (0.95 and 0.93 pound, respectively), other forms of potatoes (0.57 pound), sweets and desserts (0.41 pound), refined grains (0.39 pound), other fried foods (0.32 pound), 100-percent fruit juice (0.31 pound) and butter (0.3 pound).

Question 1: The only things that most of us would disagree with here are the red meats and the butter. Can we attribute these discrepancies to recall bias? Doesn't that taint all the other findings that we agree with (which, let's face it, are in the great majority). Maybe it's because they don't distinguish between grass fed and regular supermarket meat? Does that mean we should only eat red meat if we can afford grass fed? But why the butter?

They also enumerated what, according to the study, leads to weight loss:

Also not too surprising were most of the foods that resulted in weight loss or no gain when consumed in greater amounts during the study: fruits, vegetables and whole grains. Compared with those who gained the most weight, participants in the Nurses’ Health Study who lost weight consumed 3.1 more servings of vegetables each day.

They also mention that yogurt and nuts are associated with long-term weight loss.

Question 2: Here, we would all agree with the veggies and some of us would agree with moderate fruit intake. But whole grains? I know they're marginally better than refined grains, but still.

On the whole, I think most of these results are in line with Paleo, which is refreshing and somewhat surprising. However, I can't seem to figure out why increased butter and red meat intake is associated with weight gain, while whole grains are associated with weight loss. My initial thought is that people who choose to eat whole grains over refined grains do so mostly to lead "healthy" (albeit SAD) lives; therefore, in other aspects of their lives they would also choose healthier behaviors that could confound the findings (e.g. they floss, they choose to take the stairs more often, etc...all those little factors that go unmeasured but that could add up to a big protective effect).

Since this is Harvard, they did of course adjust for the usual: physical activity, smoking, etc. Here's a link to the abstract.

Thoughts?

flag	asked Jul 21 2011 at 7:39 Satapa 569●3●9

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I guess I should add that I'm in Epidemiology (though not Nutritional Epi) so I would like my field to bear out what I already know from Paleo about real nutrition. And it seems like it's moving in that direction, even though it's not a perfect endorsement. – Satapa Jul 21 2011 at 12:38

Happy Now · Answer 1 · 2011-07-21 08:30:22Z UTC

Maybe the whole grains caused weight loss because the participants were slowly wasting away from malabsorbtion and possibly undiagnosed celiac sprue? Weight loss doesn't equal health, I wish they'd stop using that as their main marker.

As for the weight gain with grain fed red meat I'm thinking antibiotics and an unfavorable omega 6 to 3 ratio in the meat could certainly do it through killing good gut bacteria and causing inflammation in people. The other thing that comes to mind is barbecue sauce, and/or ketchup (like in meatloaf). Adding 1/3 cup of smokey flavored HFCS to any meal is probably going to add up in the long run.

As far as what butter generally goes on in the SAD, I'm guessing they didn't take toast and jam into the equation.

I've heard many critical reports about the Nurses Health Study being cherry picked for data to support whatever hypothesis is popular at the moment, so I tend to take any panicked updates about what's good and bad for us from it with a grain of salt.

As far as waiting to buy grassfed beef until it is affordable, I've found grassfed liver and ground beef to be cheaper when I order it directly from a rancher than the feedlot stuff is at the store, so I don't think that is a valid justification for not eating grass fed.

Heather · Answer 2 · 2011-07-21 09:50:12Z UTC

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In regards to the red meat, wouldn't most SAD people be eating hamburgers on buns, hot dogs on buns, and deli meats on buns? Is it the red meat, or the buns?

answered Jul 21 2011 at 9:50

Heather
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Welcome Heather! Yes, I suspect that in SAD populations (how many of the nurses are Paleo?) meat eating would correlate with unhealthy behaviors otherwise, and the whole grain eaters probably also eat piles of vegetables. It would be interesting to see all the variables that they controlled for. – Karen Jul 21 2011 at 10:15

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Same goes for the butter, they're probably smearing it on rolls, muffins or adding a ton of it to recipes. I use ghee in cooking, but it's too concentrated to use as a straight spread. – Nemesis Jul 21 2011 at 11:27

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They adjust for bread consumption (both whole grain and refined carbohydrates separately) so it's just the meat (or, @Nemesis, the butter). If you look at the paper, they adjust for a lot, every other major type of food is in the regression equation. The sample size is so large that they can do that without blowing up the model. – Satapa Jul 21 2011 at 12:19

There was a study discussed over at Tender Grassfed Meat, looking at the omega-3 difference. I'm sure the NHS didn't control that variable. As for the butter, I personally use the pastured stuff as opposed to Land O'Lakes, which has more vit A, D, CLA, etc... Anyway, here's the link: tendergrassfedmeat.com/2011/07/19/… – Heather Jul 21 2011 at 17:02

cliff · Answer 3 · 2011-07-21 12:11:38Z UTC

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They're findings are based on correlations in a epidemiological study, basically that means that these findings mean jack squat for the most part. Until they do clinical trials the conclusions don't hold a lot of bearing.

Potato products for example are correlated with one of the highest weight gains but it probably has very little to do with the potatoes and more to do with the polyunsaturated fats that the potatoes are fried in, french fries/chips are a lot easier to eat then mashed potatoes. Likewise with meat and butter, SAD people don't eat these plain they eat them in extravagant recipes with other toxic foods that enable them to vastly overeat.

Whole grains are harder to digest and way harder to overeat on.

They don;t say what the weight gain is either, muscle, fat, water, glycogen?

edited Jul 21 2011 at 12:11

answered Jul 21 2011 at 10:56

cliff
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Clinical trials are not truly random either, because people drop out (whether they're lost to follow-up, don't like the side effects, waited until they got payed and left, etc.) and it's safe to assume that the people who drop out are different than the people that don't. I'm in epidemiology, and while it's not perfect, it's not worthless either. There's bias in every kind of study, although admittedly observational studies are more susceptible. But this is a prospective cohort, which is the best of the best in epi. I'm just trying to make sense of it, critique the study. – Satapa Jul 21 2011 at 12:24

They seem to have focused the study on obesity and its causes. I doubt anyone who gained 4lbs per year in this study was bulking up and putting on muscle. – TomInTexas Jul 21 2011 at 12:31

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The biggest issue with this study imo is that we have no idea what the weight gain is. Did people gain weight eating red meat because they gained muscle? Also people can gain weight on just about any food so I don't get what it would even mean health wise if all there findings were true. – cliff Jul 21 2011 at 12:33

Tom you doubt that but that doesn't make it true. I;m just pointing out some fatal flaws in this study. – cliff Jul 21 2011 at 12:35

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If you look at the increasing rates of obesity, I would agree with TomInTexas that the great majority of people are gaining fat, not bulking up. And no, it's not a perfect metric, but with 120,000 people what should they have done instead? Submerge everyone in water to get a precise body-fat measurement? – Satapa Jul 21 2011 at 12:41

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TomInTexas · Answer 4 · 2011-07-21 12:27:26Z UTC

I liked this part:

Alcohol intake had an interesting relationship to weight changes. No significant effect was found among those who increased their intake to one glass of wine a day, but increases in other forms of alcohol were likely to bring added pounds.

It makes me feel better about the glass of wine I had last night. Not that I needed much of an excuse, but its nice to find one :)

Their research method leaves much to be desired:

Every two years, they completed very detailed questionnaires about their eating and other habits and current weight.

How much do you remember about what you ate on July 21, 2010? I couldn't tell you anything about it, honestly. And the way the questionnaire is worded will strongly influence how a meal gets classified.

That said, its still an interesting study. And as someone who is preparing to go into the healthcare industry and who is married to a nurse, its of personal interest to me.

The Quilt · Answer 5 · 2011-07-21 12:05:43Z UTC

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Red meat in this study was grain fed and the butter non pasture so this does not surprise me at all.

answered Jul 21 2011 at 12:05

The Quilt
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That may be true but I doubt these items being pasture fed would have too much of a difference on weight gain – cliff Jul 21 2011 at 12:12

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I lost my weight on almost exclusively on organic grainfed. The thing about grainfedis more about what it's missing but there's roundabout ways to get it in your diet. (pastured butter with a side of fish oil anyone?) – luckybastard♦ Jul 21 2011 at 12:23

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I lost all of my weight on cheap supermarket meats. Nothing organic or GF about it. GF and organic are great, but if its not in your budget normal meats are still better than SAD – TomInTexas Jul 21 2011 at 12:29

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amen, tom. i should have also mentioned my parents are losing weight and improving their health on cafo beef. no it's not optimal but why let the perfect be the enemy of the good? – luckybastard♦ Jul 21 2011 at 12:54

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Losing weight is one aspect. Being healthy as one ages is quite another – The Quilt Jul 21 2011 at 18:11

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Ambimorph · Answer 6 · 2011-07-21 14:17:00Z UTC

I think the bias is more subtle than just recall. Think about what kind of person, particularly during that time, was eating french fries and red meat, sweets and desserts, and what kind of person was eating fruits and vegetables, nuts and yogurt. Do you think one group might have been more health-conscious? If so, what other lifestyle choices might they have been making? Were the latter group exercising more, or actively trying to lose weight by caloric restriction? Were the former group more motivated by following their desires than health concerns? In a study like this, there is just too much self-selection that carries with it a host of factors. Epidemiology is a nightmare of multidimensionality.

The Loon · Answer 7 · 2011-07-21 14:59:10Z UTC

This study does not at all show what contributes to weight gain. If they'd look, they would probably find that more fat people wear size 24 clothing. But they would never say that wearing size 24 contributes to fat gain. Same with food. Harvard should know better. The truly poor nutrition research they have cranked out over the years detracts from their reputation.

Latest from Nurses Health Study, etc.

7 Answers