Sunshine and Light

Low fat or no?

Probably everyone on the planet has seen this story and reached for the fried Mars bar by now. Christine was kind enough to look up the actual study from JAMA and her thoughts and mine sort of track:

First of all it was an impressive study in the size of the group studied (Total: 48000) with some good markers. It's great to see actual studies being done about nutrition.

but...

Like any study, there has to be some limit to the length of the study. This was done on women over the age of 50. A study has not yet been done to see the long term effects of low fat (or higher fat as the case may be). The study specifically cut out people already eating 32% fat or less. Too bad they couldn't have been in as a separate group to compare to the control and the newly low fat crowd. Also, the study was over 8 years, so there's no telling whether that's long enough.

They relied on self-report a lot. They did have some markers that indicate the people were truthful, but what if the intervention group diverged during some months & got back on the program about folow up time? They did not track lifestyle. What if the higher fat people wanted to control their weight & started to exercise at some points which would have changed their risks. The BMI, waist, and physical activity data suggest this was not a factor, but again it was NOT controlled. Also, what about other known factors like smoking, alcohol, drugs, exposure to chemicals, etc?

They "assumed" that if people reduced their fats to 20%, they would naturally have less than 7% saturated fat. Based on what? And - their intervention group NEVER got to 20%. At lowest, the average was 24%, and by the end the average was 29%. Saturated fat these days is commonly considered to be the demon, not fat in general. And 29% is hardly low fat in terms of Pritikin or Ornish. The control group ranged from 35-37% - not very much higher than the current daily recommendations.

In other words, this study is a great first start - way to go gang! - but by no means an excuse to start cooking with lard. On the other hand, it certainly casts doubt that the extremes are worth going to in dieting. First of all, they're just hard to maintain - even with 18 nutritional counseling sessions in the first year, the group didn't manage to get to the 20% fat mark. Secondly, they may not be effective.

My theory at this point is that while I love my fatty foods, I'm doing my best to mostly eat veggies, fruit, beans, skinless chicken breasts, and other foods low in saturated fat, and as unprocessed as possible (i.e. as much homemade as I can sanely make). In other words no trans-fatty acids/partially hydrogenated oils, and limited saturated fats. My theory is that the only people ever to say fruits and veggies are bad for you are the carb fiends, and they've been acknowledged to be nutritionally disastrous from day one. Once the scientists have come to a decision about what's good for you, I'll be glad to change my diet.

But lest anyone, including myself thinks I'm nominating myself for nutritional sainthood, I'm seriously considering a big juicy burger from Molly's tonight.

posted by MyHusbandRules @ 5:50 PM