NEW YORK, July 14, 2008 – A two-year study led by researchers from Ben-Gurion University of the Negev (BGU) reveals that low-carbohydrate and Mediterranean diets may be just as safe and effective in achieving weight loss as the standard, medically prescribed low-fat diet, according to a new study published in the prestigious New England Journal of Medicine.
The study was conducted by BGU and the Nuclear Research Center in Dimona, Israel, in collaboration with Harvard University, The University of Leipzig, Germany and the University of Western Ontario, Canada.
In the two-year study, 322 moderately obese people were intensively monitored and were randomly assigned one of three diets: a low-fat, calorie-restricted diet; a Mediterranean calorie-restricted diet with the highest level of dietary fiber and monounsaturated/saturated fat; or a low-carbohydrate diet with the least amount of carbohydrates, highest fat, protein, and dietary cholesterol. The low-carb dieters had no caloric intake restrictions.
Although participants actually decreased their total daily calories consumed by a similar amount, net weight loss from the low-fat diet after two years was only 6.5 lbs. (2.9 kg) compared to 10 lbs. (4.4 kg) on the Mediterranean diet, and 10.3 lbs. (4.7 kg) on the low-carbohydrate diet. "These weight reduction rates are comparable to results from physician-prescribed weight loss medications," explains Dr. Iris Shai, the lead researcher.
The Mediterranean diet has more fiber and probably a lower glycemic index than a typical low fat diet that does not take into consideration the types of carbos. When glucose enters the blood it causes insulin release to transport it out of the blood and into cells. How the body responds to that insulin and sugar probably helps to increase weight and push one's blood lipid profile in an unhealthy direction. Cutting carbohydrates does the most to improve blood lipids.
The low-fat diet reduced the total cholesterol to HDL ratio by only 12 percent, while the low-carbohydrate diet improved the same ratio by 20 percent. Lipids improved the most in the low-carbohydrate, with a 20% increase in the HDL ("good") cholesterol and, 14% decrease in triglycerides. In all three diets, inflammatory and liver function biomarkers was equally improved. However, among diabetic participants, the standard low-fat diet actually increased the fasting glucose levels by 12mg/dL, while the Mediterranean diet induced a decrease in fasting glucose levels by 33mg/dL.
Shift toward eating more monounsaturated fats (olive oil) and fish along with veggies and nuts. Cut back on the grains - especially the higher glycemic index refined grains. Check out this online searchable database on glycemic index of hundreds of foods.
One of the steps I've taken in the direction of a higher protein diet is to cook 20 lb turkeys and eat turkey every day. It is lower in fat than most red meats and lasts at least a couple of weeks afterward in a fridge kept just at the freezing point.
The study was funded by a foundation established by Robert Atkins, of Atkins Diet fame. Though the Atkins Diet has a popular reputation as a meat-heavy, bacon-lover’s dream, those in the study who were assigned to the low-carb plan were counseled to favor vegetarian sources of fat and protein.
I think the study should be considered on its merits.
My colleagues and I at the nonprofit Preventive Medicine Research Institute and the University of California, San Francisco, have studied for more than three decades the effects of diets much lower in fat (10 percent) than the one used in NEJM study as well as lower in refined carbohydrates and higher in fruits, vegetables, whole grains, legumes and soy products.
We reported in a randomized, controlled clinical trial published in the Journal of the American Medical Association a 24-pound weight loss after one year and 13-pound average weight loss after five years in a group of men and women, much more than the 9.7 to 10.3 pounds lost in the new NEJM study. These findings were replicated in larger demonstration projects as well.
Ornish makes the important point that some evidence links higher fat diets to prostate cancer. But at least one study found saturated fat was the source of risk for progression of prostate cancer. Ornish might be painting with too broad a brush and the monounsaturated and polyunsaturated fats might provide net benefits. One study found that polyunsaturated fats are not associated with increased risk of advanced prostate cancer.
While the Atkins Foundation funded this study and the low-carb were counseled to eat a lot of protein the participants were encouraged to eat plant protein rather than animal protein. Well, it is hard to eat a lot of plant protein.
But according to the report in The New England Journal of Medicine, the low-carb dieters in the study “were counseled to choose vegetarian sources of fat and protein.'’ Although saturated fat was not specifically restricted, the dieters were told that “moderation” was recommended.
So the dieters in this study ate less saturated fats and probably less protein than full-on Atkins dieters.
We know some foods are good. Eat lots of vegetables. That's the hardest advice of all for most to follow. Eat whole fruits. When you eat meat choose leaner meats. Eat fish. Eat beans and lower glycemic index rices rather than breads.
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