By now, I'm sure most everyone has heard or read the news that a new study has come out in The New England Journal of Medicine (July 17, 2008, volume 359) saying that low carb diets are more effective for weight loss than low fat diets. That's what all the headlines are saying. BUT, that's not exactly what the study concluded. What the study actually concluded was:
"Conclusions Mediterranean and low-carbohydrate diets may be effective alternatives to low-fat diets. The more favorable effects on lipids (with the low-carbohydrate diet) and on glycemic control (with the Mediterranean diet) suggest that personal preferences and metabolic considerations might inform individualized tailoring of dietary interventions. "
To me, that's saying something slightly different than what the headlines read. It's saying that low carb diets may be more effective as an alternative to low fat, that low carb did have show a better lipid profile, specifically Mediterranean diet showed a better glycemic profile, and that (to me this is the important part ) is that your diet should reflect your health needs and goals.
The reason why I make such a distinction is because I feel very strongly that although a lot of diet basics are the same: Eat less, exercise more, eat fresh wholesome foods, I get the willies when any headline comes out saying "This is the one and only way you can lose weight" or "This diet is the one and only one that works" which is the impression I got from most of the articles I read ABOUT the study before reading the study itself, which to me, confirmed common sense: we eat to live and that means we have to make our diet line up with our particular health needs.
For the complete text of the study, click here: Weight Loss Study.
I found the study's definition of the three diets extremely interesting especially since the way the study defined them differed from how I automatically defined them from my own experience and knowledge.
The low-fat, restricted-calorie diet was based on American Heart Association20 guidelines. We aimed at an energy intake of 1500 kcal per day for women and 1800 kcal per day for men, with 30% of calories from fat, 10% of calories from saturated fat, and an intake of 300 mg of cholesterol per day. The participants were counseled to consume low-fat grains, vegetables, fruits, and legumes and to limit their consumption of additional fats, sweets, and high-fat snacks.
The moderate-fat, restricted-calorie, Mediterranean diet was rich in vegetables and low in red meat, with poultry and fish replacing beef and lamb. We restricted energy intake to 1500 kcal per day for women and 1800 kcal per day for men, with a goal of no more than 35% of calories from fat; the main sources of added fat were 30 to 45 g of olive oil and a handful of nuts (five to seven nuts, <20 g) per day. The diet is based on the recommendations of Willett and Skerrett.21
The low-carbohydrate, non–restricted-calorie diet aimed to provide 20 g of carbohydrates per day for the 2-month induction phase and immediately after religious holidays, with a gradual increase to a maximum of 120 g per day to maintain the weight loss. The intakes of total calories, protein, and fat were not limited. However, the participants were counseled to choose vegetarian sources of fat and protein and to avoid trans fat. The diet was based on the Atkins diet (see Supplementary Appendix 2).22"
As I read over the details of each diet, I found that both the Low Fat Diet and the Mediterranean Diet were very familiar with how I perceive each of those but I was literally shocked to see that the Low Carb dieters were "counseled to choose vegetarian sources of fat and protein." That deserves a Scooby Doo "wwrrrraaAAATTT?"
Being not much of a meat eater I admit the Atkins Diet never caught my fancy but when it first came out I remember several meat-loving friends going on it, losing weight, and raving about how great it was to eat all the hamburgers (bun-less, of course), steak, bacon, and eggs they wanted and still lose weight. To me, Atkins is synonymous with eating meat.
Confused, I went to the official Atkins web site to check out my knowledge of the diet. What I found was that no where in the different Phase information did it say "choose vegetarian sources of protein." (I have no quibble with the vegetable/olive oil portion of the specified diet instructions.) It does say several times to choose low fat poultry and meats but never promotes vegetarian sources of proteins the way the study listed.
Here's the question it brought up for me: One 1/2 cup of boiled lentils equals approx 10 grams of protein at 115 calories. 2 oz of extra lean ground beef equals approx 10 grams of protein at 85 calories. BUT. With in that 115 calories of the beans, not only do you get the 10 grams of protein but you also get approx 9 grams of complex carbohydrates.
Does that make anyone else wonder why the Atkins-style diet specifically promoted the low carb dieters to choose vegetarian sources of protein? It simply didn't make sense to me to say "low carb", whether or not it's an obvious homage to Atkins, and then encourage the dieters to choose vegetarian, or complex carb, forms of protein. To me, once you tell the low carb dieters to choose vegetarian protein, you're back to the Mediterranean concept without the advantage of all of the vitamins, minerals, fiber, and antioxidants from the additional vegetables and fruits consumed with the Mediterranean diet.
To be honest with you, I don't have the answer. I'm curious why the study was set up that way.
Some of the good highlights were that the low carb-style diet improved lipid profiles for heart disease. That makes sense to me. We've long known that there's a direct link between refined carbs and triglyceride levels (basically the fat floating in the blood) so removing those would improve cholesterol levels. That makes sense to me.
Another interesting outcome of the diet was that the Mediterranean Dieters ended with a better glycemic stability than the people on the other two diets. Again, that makes sense to me. The key to Diabetes is controlling blood sugar, again losing the refined carbs but still eating plenty of complex carbs with their fiber and protein makes sense to me as an approach.
The one depressing result was the weight loss. I pretty much laughed in the face of all the headlines I read about "low carb diets are the better weight loss answer!" The fact is the study took place over TWO YEARS. The low carb and Mediterranean dieters were limited to 1500 calories a day for women and 1800 calories a day for men. The low carb dieters weren't restricted in the calorie sense. The mean weight loss ranged approx 6lbs for the low fat dieters up to 10 lbs for the low carb dieters with the Mediterranean dieters in between. 10 lbs. Over TWO YEARS. I don't know about you but I find that depressing. I'm hoping most of the study's participants were at or near recommended body weight.
Another depressing result was the the adherence rate for the low carb was the smallest of the three diets. Low fat dieters had an adherence rate over the 2 years of 90.4, Mediterranean 85%, and low carb diets of 78%. Or maybe that's good. It depends on how you see it. Even with the lowest number, sure 22% didn't comply but 78% DID.
In the end, based on the way the study performed, it recommended the common sense approach that we all know:
"This trial also suggests a model that might be applied more broadly in the workplace. As Okie recently suggested,33 using the employer as a health coach could be a cost-effective way to improve health. The model of intervention with the use of dietary group sessions, spousal support, food labels, and monthly weighing in the workplace within the framework of a health promotion campaign might yield weight reduction and long-term health benefits. "
What I took away from the study was that what we eat, our diet, should reflect our personal health needs and our personal food preferences and that we need to do whatever it takes to keep ourselves motivated. Exercise wasn't integrated into the study but, to me, it's obvious that the old rule of "eat less, exercise more" cuts to the chase.