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|Neue Studie [Beitrag #281966]
||Mi, 23 Juli 2008 00:00
Vielleich kam da in Deutschland auch was im Fernsehn, oder vielleicht auch nicht. Es wurde ein 2 jaehrige Studie in Israel von Harvard (School for Pulic Health) durchgefuehrt. Ergebnisse wurden im New England Journal of Medicine (sehr angesehen)veroeffentlicht. Es gibt mehrere Internetlinks aber dieser Text hier ist leicht verstaendlich.|
THAT NEW LOW-CARB vs LOW-FAT STUDY
This week, a new study on diet and weight loss grabbed more headlines than a Britney sighting. You might have seen it reported on the Today Show, or read one of the many (misleading) headlines: "Low Carb Diet Beats Low-Fat in Diet Duel" (MSNBC), "Low Carb Diet Best for Weight, Cholesterol" (Associated Press), or- the most reasonable- "Study Fuels Low-Fat vs. Low-Carb Debate" (Wall Street Journal).
Because of the importance of this study- which after all was published in the ultra-conservative New England Journal of Medicine- I'm going to deviate from our usual newsletter format and focus exclusively on this study, which- like many diet studies- was poorly reported and somewhat misunderstood.
For starters, here's what actually happened:
Israeli researchers recruited 322 moderately obese subjects and randomly assigned them to one of three dietary groups.
Group one followed a low-carb diet without any restriction on calories. For the first two months they limited their carbohydrate intake to 20 grams a day (the exact amount on the Induction Phase of Atkins) and were then encouraged to increase their intake of carbs up to a maximum of 120 grams a day of carbs. (Sharp eyed readers might note that 120 grams of carbs hardly constitutes an Atkins diet, even during the most generous "maintenance" phase. For someone eating 1500-1800 calories a day diet, that would be between 25-40% of calories from carbs, closer to "The Zone" than to Atkins. But I digress.)
In contrast, both the Mediterranean and the low-fat groups were calorie limited: 1500 calories a day for women and 1800 for men. The low-fat group followed the standard American Heart Association guidelines (30% of calories from fat). The Mediterranean group were allowed up to 35% fat, mostly from olive oil and nuts, and were counseled to substitute beef and lamb with poultry and fish.
Interestingly, all three groups lowered their calories significantly compared to where they started, even though the low-carb group wasn't specifically told to do so, meaning the low-carb group "naturally" ate less calories without even trying. (This is an important point, since I've long maintained that a low-carb diet is easier to follow for many people-- especially those with sugar addictions-- because it doesn't stimulate the appetite like high-carb diets frequently do.)
Fast forward two years: the low-carb group lost the most amount of weight, the low-fat diet brought up the rear and the Mediterranean group was in the middle.
The weight loss results, however, were only part of the picture. The low-carb group had the highest increase in HDL ("good, protective cholesterol"), most improvement in cholesterol ratio, and the greatest reduction in triglycerides- an important risk factor for heart disease that I firmly believe is more important than cholesterol- (triglycerides didn't budge in the low fat group).
It gets better. Low-carb dieters saw their C-Reactive Protein go down the most. C-Reactive protein is a very good measure of inflammation, something I think we need to be way more concerned with than cholesterol. Inflammation is a silent killer and a component of every degenerative disease from heart disease to obesity. Incidentally, C-Reactive Protein levels barely budged in the low-fat group.
Now for the "bad" news. The actual amount of weight lost on all three diets was pretty pathetic-- average of about 12 pounds for the low-carb group, 10 for the Mediterranean group and 7 for the low-fat group- statistically significant results, but pretty depressing considering this was over a two year period! Remember, though, those numbers were averages- some people lost a lot more (the highest number of pounds lost was lost on the low-carb approach, by the way).
So the first question that comes to mind is this: Did the subjects actually stick with their diets?
This is an impossible question to answer perfectly, and it's not the researchers fault. Short of locking folks in a metabolic ward for two years and counting every calorie served to them and left on their plate, there's no way to completely track compliance with any diet- people cheat, misunderstand the instructions, underreport what they ate, forget, and occasionally outright fib.
But the researchers were smart, and worked with what they had. In Israel, the biggest meal of the day is eaten at lunch, and in this study, everyone participating worked at the same facility and ate lunch at the company cafeteria. The employers cooperated fully with the researchers- all food was labeled and color coded, plus the subjects gave written reports about what they were eating outside company hours. If you're a researcher working with "free living" subjects, that's pretty much all you could hope for. Still, we all know what an evening (or a morning) or a weekend can do to sabotage any plan.
So, a lot of weight lost? Not really. But what's really remarkable about the results is that they didn't gain any weight over 2 years (and managed to lose some to boot!) Most people in that demographic (slightly obese, middle aged), left to their own devices, would continue to pack on the pounds. The fact that these people not only didn't gain but actually lost- albeit not that much- shows that there's hope.
This program shows that employers can actually make a big difference. What worked here- besides the diet programs themselves- was the group support, the counseling, the accountaility and the change in choices that was made available at their workplace.
That's a pretty optimistic finding, if you ask me. (Employers and schools- take notice!)
Most important of all, the study shows that there are health benefits to a low-carb approach that go way beyond weight loss. Lowered C-Reactive Protein, lowered triglycerides and increased HDL is nothing to sneeze at and a nice slap in the face of the establishment that keeps telling us how "unhealthy" low carb diets are!
And call me crazy- I can't help wondering if the low-carb group would had lost even more weight if they had eaten less than the 120 grams of carbs these folks ate, all the while keeping calories at a moderate, reduced amount and incorporating other lifestyle changes like exercise and stress reduction. Can you imagine? A more reasonable level of under 100 grams a day (or even less) might have made a lot of difference- that's a level that seems to work the best for people who have problems with sugar, insulin and carbohydrates in general.
The best we can say about this important study is that it got a lot of attention (after all this was the New England Journal) and gave credibility to the researchers stated conclusion that there are other ways to go besides low-fat. And to the conclusion that no one program works for everyone, and that some people may be more metabolically suited to low-carb (just as some may thrive on vegetarian or raw food diets).
And as far as the dismal weight loss results, let's just remember that weight loss is a tough nut to crack- but with the right match between program and person, the right social support system, a level of determination and commitment, it can be done.
And frequently is- often with much more dramatic results than were seen in this study.
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