So this — Low-Fat Diet Tops Low-Carb in Long Run — is going around the interwebs today:
In the study, researchers started with a group of 132 obese people who weighed an average of 289 pounds before starting either a low-fat diet, a calorie-restricted diet with less than 30% of daily calories from fat, or a low-carb diet with fewer than 30 grams of fat [this probably was 30g carbs, not fat] per day for 12 months.
At 6 months, the low-carb dieters had lost more weight, but by 12 months, there was no difference between the two.
But here’s the kicker:
Three years after the study began and two years after the diets ended, researchers followed up with 40 people in the low-carb diet group and 48 in the low-fat diet group.
They found people in the low-carb diet group weighed an average of 4.9 pounds less than before they started dieting while those in the low-fat diet group weighed an average of 9.5 pounds less than they did at the start of the study.
While this sounds like a big win for the low-fat diet (or at least the way the media and low-fat fans are pushing this), look at the numbers. These folks averaged nearly 300 pounds. Yet three years after the study began, neither group had lost or maintained even 5% of their weight.
I guess the researchers must have just loved the statistical difference between 4.9 lbs and 9.5 lbs, but unless you’re a size 2 trying to get into a size 0, this study isn’t a ringing endorsement for either diet — or diets in general!
Weight Maven is written by Beth Mazur. Beth believes that obesity is more symptom than cause and that the real problem is our Western diet -- especially sugar, refined grains, and industrial oils. Beth writes about nutrition, ancestral health, & food policy. And cats! 
Nice. So is there any discussion about how these two diets made the participants feel? Or any discussion of other changes in health?
Or are we still just looking at weight?
Very good question. The problem with many of these studies is compliance, especially long-term. That could be related to how the participants feel, but I suspect that it’s just as much related to the difficulty of staying either low-carb or low-fat in our all food, all the time environment.
The current study is behind the journal’s pay wall, but I found their report of the study after one year here:
http://www.annals.org/content/140/10/778.full
Here’s a summary:
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Results: By 1 year, mean (±SD) weight change for persons on the low-carbohydrate diet was −5.1 ± 8.7 kg compared with −3.1 ± 8.4 kg for persons on the conventional diet.
Limitations: These findings are limited by a high dropout rate (34%) and by suboptimal dietary adherence of the enrolled persons.
Conclusion: Participants on a low-carbohydrate diet had more favorable overall outcomes at 1 year than did those on a conventional diet. Weight loss was similar between groups, but effects on atherogenic dyslipidemia and glycemic control were still more favorable with a low-carbohydrate diet after adjustment for differences in weight loss.
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Later in the discussion, they add this to the study’s limitations:
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Second, most persons did not meet their dietary targets (<30 g of carbohydrate daily in the low-carbohydrate group and reduction of 500 calories per day in the conventional diet).
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Not sure why the WebMD story isn't "Low-Fat and Low-Carb Diets Suck Big Time in Short- and Long-Term."