The evidence that the Low Carb Age is upon us keeps amassing, albeit with the usual caveats to assuage guilt. As the authors of Mistakes Were Made (But Not by Me) tell us, people in positions of authority rarely admit they were wrong.
Nevertheless, the truth begins to squeak out. This week the NY Times’ Tara Parker-Pope’s Phys Ed column reports on a significant new study from Johns Hopkins to be published this Friday:
With the memory of Memorial Day cheeseburgers and bratwursts still lingering, many of us may be relieved to hear that a new study suggests that a meaty, high-fat, Atkins-style diet can do more than contribute to rapid weight loss. It may also be less unhealthy for the heart than many scientists had feared — provided you chase the sausage with a brisk walk.
So Close, Yet So Far
Parker-Pope makes the mistake of insisting exercise was proven to be part of the solution, but the study shows no such thing. It specifically compares a low fat to a “low carb” diet, both with the same amount of exercise. As The Behavioral Medicine Report explains:
Low-carb dieters showed no harmful vascular changes, but also on average dropped 10 pounds in 45 days, compared to an equal number of study participants randomly assigned to a low-fat diet. The low-fat group, whose diets consisted of no more than 30 percent from fat and 55 percent from carbs, took on average nearly a month longer, or 70 days, to lose the same amount of weight.
Both groups had an exercise component. In the absence of a correlating study showing that the same diets without exercise has a different outcome, Parker-Pope’s assertion is without any foundation. Pre-conceived notions are hard to shake.
How Low is Low
As we’ve seen in other studies, the term “low carb” used here is inexact. The low carbohydrate group consumed up to 30% of their calories from carbs. Considering this a low carb diet is a bit of a stretch. Most people adhering to a low carb diet to lose weight start with about 40 grams of carbohydrates per day, or 160 calories from carbs. For a healthy man consuming 2,500 calories per day, carbs during Induction on Atkins represent about 7% of calories. That same man on the test diet in this study would be consuming about 185 grams of carbs. That’s higher than many people on a low carb maintenance diet.
This study did reduce calorie content by about 700 calories over the baseline for each individual. Even for a 2,000 calorie diet, the “low carb” dieter is consuming 150 grams of carbs.
Why Calories Don’t Matter
This study provides yet another example why the “calories in / calories out” model is flawed, as the low carb group lost weight 30% faster than the low fat group. They both consumed 700 fewer calories per day than before, but the low carb group lost weight faster. If the body reacts to all food the same way, as a strict “calories in / calories out” model suggests, then both groups would have lost weight at the same rate. But in study after study, we find that the low carb group loses weight faster and with less hunger than the low fat group. What you eat matters as much as how much you eat.
The Original Purpose
The trial was designed to test the differences in vascular function for people on both diets, and both showed no change. It is the first study to actually test vascular function among a group of people. That is good news for people considering a low carb diet. As lead investigator exercise physiologist Kerry Stewart, Ed.D, says:
“Our study should help allay the concerns that many people who need to lose weight have about choosing a low-carb diet instead of a low-fat one, and provide re-assurance that both types of diet are effective at weight loss and that a low-carb approach does not seem to pose any immediate risk to vascular health,” says Stewart. “More people should be considering a low-carb diet as a good option,” he adds.
The study is due to be published Friday, June 3.