[This was originally posted on a weight loss website on Feb 17.]
I saw an article by a nutritionist on a weight loss website that I found perplexing (OK, annoying). Maybe you have read it, too. Here's the link:
To get a clearer picture of what this is all about, I went to the original study. I remembered this one, because it was featured in a link on another member's blog several months ago. It was by DS Weigle and others. I promised you all I'd get back to that study, so here I am!
The nutritionist mentioned that the study compared 3 different diets, but that is not really the case. In this experiment, participants served as their own controls. This is sort of a weird way to do a study, especially one involving hormonal issues that probably take more than two weeks to settle out. I think I understand why they did this, but my point is that this move brings up other problems (and they did discuss these problems at the end of the study.) I actually think this is a pretty good study compared to earlier ones, just really concerned about how it is being interpreted and mis-interpreted by the media and by others.
Usually, researchers get two groups of people, and give one group a special diet and the other group serves as a control. In this experiment, the participants started with a baseline diet. They went for two weeks on an "isocaloric" 15:35:50 diet. (That's 15% protein, 35% fat and 50% carb.) Then they switched to a 30:20:50 diet for two weeks (more like the Zone diet). Then they went for 12 weeks on the 30:20:50 diet, but were told they could eat all they wanted. And, they were compared with their own baseline. The baseline diet wasn't really a treatment, but it was sort of like when you catch snails and then feed them a special diet for a few weeks before you eat them.
Sounds like a prescription for eating more protein, but is it?
The first issue is that even though the abstract said it was isocaloric in the first stages, it wasn't. During the first 2 weeks, the researchers tweaked the diet so that the participants wouldn't lose too much weight. Participants lost weight quickly, and as they were brought into the clinic, measured and weighed, the diet was tweaked. The first 2 weeks was just sort of like a boot-camp, to flush out some of the issues and figure out everyone's individual calorie level. It was never intended to be a treatment level. After this 2-week period, the real fun began.
This study wasn't about comparing a low-protein diet with a high-protein diet at all. It wasn't even about weight loss. It was not done with participants who were trying to lose weight. It was conducted to dispel concerns about an earlier similar study done by the same researcher and to measure hormone levels as they relate to feelings of hunger. The first study had some big concerns. Though it was touted as a study to determine the effects of a low-fat diet on hormones and satiety, the researchers replaced the reduced fat with extra carbs, while keeping protein at a constant 20%. In the second experiment, the researchers replaced the reduced fat with extra protein and kept the carbs constant at 50%.
But OK, I'm getting ahead of myself. Back to THIS study. The real problem? Some readers responded to the nutritionist's article concerned about the sample size. I am not as concerned about the number of participants as I am about who they are.
Participants were mostly women, but were specifically excluded from the study if their BMI's were over 30. In fact, the BMI range was from around 22 to 30, with an average BMI of around 26! Potential participants were also excluded if they did more than 30 minutes of exercise 3 times a week, or if they smoked, or if they had been either an Ornish-type diet or an Atkins-type diet, or if they had any chronic disease like diabetes, etc., or if they had more than 2 drinks a week, or if they were "unhealthy", or if they were preggo.
Now I don't know what this sounds like to you, but to me, it pretty much excludes everybody on the weight loss website, except a few of the younger women trying to get into prime shape before their wedding. (And, wedding planners, not to discount your journey AT ALL, but if you think it's hard now, wait till you have had a couple of kids or go through menopause!!) Gosh, we sure do exercise more than that at least, and a quick look of the intro member pages shows we have all sorts of chronic diseases and many of us start out as obese.
Why is this study being used as a benchmark for recommendations for obese people with chronic illnesses? Many of the participants weren't even considered overweight. Do I really care how hungry they were on different diets? People who weren't dieting, weren't that fat to begin with? Oh come on, how would or should this study apply to the rest of us?
Stay tuned for more info on this study. (It gets even better!) After that, I'll compare this author's two studies, tell y'all what study they really should have done along with these two, and then show you a third study that you might REALLY want to pay attention to, that you probably won't find cited in an article here on that particular weight loss website, but should!
Here's the study that the nutritionist referred to:
And here's a member's original blog: www.sparkpeople.com/mypa
And my earlier response to the member's blog: http://exceptionallybrash.blogspot.com/2011/03/refueling-protein-debate-and.html