Low carb diet study in NEJM
It was headline news on July 17 when an important new study was published in the New England Journal of Medicine comparing weight loss on one of three diets- low-fat, low-carb and Mediterranean. And low-carb came out on top.
The study gained a ton of media attention for three reasons:
1) it was one of the longest studies comparing low-carb and low fat, following subjects for 2 full years.
2) it was published in one of the two most respected and conservative peer review journals of medical information in this country and
3) it added to the mounting evidence that an Atkins-type approach to eating is not only effective for weight loss, but has important health benefits as well.
Researchers recruited 322 moderately obese subjects and randomly assigned them to one of three dietary groups.
Group one followed a low-carb diet without caloric restriction. For the first two months, the low-carb group 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 vegetables, fruits, whole grains and legumes up to a maximum of 120 grams a day of carbs. Calories weren’t limited, nor was the amount of fat or protein.
In contrast, both the Mediterranean and the low-fat groups were limited to 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 no more than 1/3 of them from saturated fat, no more than 300 mg a day of cholesterol). 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 from when the study started, even though the low-carb group wasn’t told to do so, meaning the low-carb group “naturally” ate less calories without even trying. (This is an important point, since we’ve long maintained that Atkins is easier to follow because it doesn’t stimulate the appetite like high-carb diets frequently do.)
After two years the results were clear: The low-carb group lost the most amount of weight, (followed by the Mediterranean group). The low-fat diet brought up the rear.
These results were important but they’re only part of the picture. The group that had the highest increase in HDL (‘good, protective cholesterol’) was the low-carb group. In addition, triglycerides- an important risk factor for heart disease that some say is more important than cholesterol- decreased significantly in the low-carb group (triglycerides didn’t budge in the low fat group). Plus the low carb group had the greatest improvement in their cholesterol ratio (the ratio of total cholesterol to HDL) which is often used as a marker of heart disease risk.
It gets better. As readers of this newsletter know, inflammation is a silent killer and a component of every degenerative disease from heart disease to obesity. One of the best markers for inflammation is a blood component called C-Reactive Protein. Low-carb dieters saw their C-Reactive Protein go down the most-- it barely budged in the low-fat group.
A subgroup of diabetics reduced their blood sugar (glucose) slightly more on the Mediterranean diet than on the low-carb diet- but this might have been due to their being told to emphasize olive oil which contains valuable plant compounds called phenols. However, there is absolutely no reason someone following Atkins couldn’t use as much olive oil -- Atkins does not “dictate” the type of fat you eat, it only restricts carbohydrates. In fact, a study published last year kept dieters on a strict Atkins induction diet of 20 grams of carbs a day while making sure everyone included 5 tablespoons of olive oil along with their other food- the Atkins dieters saw their glucose fall by more than 50%!! (It’s worth pointing out that diabetics on the low-fat program actually saw an increase in their blood glucose!)
While the total amount of weight lost in absolute numbers doesn’t sound like a lot (average of about 12 pounds for the low-carb group, 10 for the Mediterranean group and 7 for the low-fat group), three things are worth pointing out.
First, those following the low-carb program ate up to 120 grams a day of carbohydrate (and still came out on top!). Can you imagine how well they might have done if they had limited their carb intake to be more in keeping with the four stages of Atkins Nutritional Approach? (After all, 120 grams a day is what the most metabolically advantaged people in the fourth, maintenance stage of Atkins typically consume!) Remember, during the progression through the four phases of Atkins, an individual begins to gradually increases his intake of healthy carbs, exactly the ones used in the study- nuts/seeds, low-sugar fruits, legumes and even whole grains in reasonable quantities- to allow a complete balanced intake without exceeding the level of carbohydrates that will again induce fat deposits. Gradually introducing healthy carbohydrates this way allows each individual to learn the amounts of food he can reasonably consume- typically under 80-120 grams-- without gaining fat.
Second, the differences between the Mediterranean diet and the low-carb approach were in reality not all that substantial. Other than the fact that those on the Mediterranean diet had to limit their fat to 35% of their diet, there was a huge overlap between what people on these two programs actually ate. The biggest differences- in weight and in all important blood measures- were seen when you compared the low-fat group to the other two!
And finally, remember that although the actual number of pounds lost might not seem substantial, it was just an average. Many people lost a lot more- and the person who lost the most (27.5 pounds) was actually following the low-carb approach!
The researchers concluded that both the Mediterranean and the low-carb diet were “effective alternatives to the low fat diet for weight loss and appear to be just as safe as the low fat diet” In addition, they added, “both of these diets had beneficial metabolic effects”.
We at Atkins have long maintained that no one diet plan works for everyone, and we’re happy to see this study adding to the growing body of evidence that the Atkins nutritional approach not only works well for weight loss, it produces significant health benefits as well.