Google news alert! Twitter is blowing up ! Facebook is on fire! The news is spreading like wildfire that low carb diets have now been proven to be the best way to lose weight, melt fat, and light your metabolism on fire! Well, at least that’s the way the word has spread. Sarcastic over-exaggeration aside, all this buzz is coming from a recent research study published in the Annals of Internal Medicine. It adds to a growing body of evidence that the obesity epidemic is fueled by our insatiable desire for carbohydrates (for more read my prior post Maybe a Calorie Isn’t Just a Calorie). If you are a loyal follower of the counter revolution you know that whenever you read about scientific research in the media you absolutely have to take it with a grain of salt. If you’re not a loyal follower, why not – enter your email and join the counter revolution. Anyways, the media is not interested in giving you the facts or improving your health. They are interested in getting your eyes on their advertisements and improving their profit margins. This will often lead them to exaggerate claims so you have to be careful. My job is to bring you an unbiased interpretation. For this reason, I wanted to give you a clear explanation of the study.
The trial included 148 healthy adults who were a assigned to either a low-fat or low carb diet. The low carb group was instructed to eat less than 40 grams per day of carbohydrates. The low fat group was instruct to eat less than 30% of their calories from fat. Participants were given handbooks with recipes and nutrition education to guide them. They also had frequent meetings with nutritionist and counselors. There were no recommendations for exercise.
Results showed that the low- carb participants lost close to 12 lb after one year whereas the low-fat group lost only about 4 lb in the same period of time. This was after cutting their carb intake from 48% of their calories to about 20%. The low carb group also had greater decreases in waist circumference and body fat percentage and a greater decrease in risk factors for heart disease.
There are some caveats. The researchers made no recommendations about, nor did they measure, exercise. It may be assumed that exercise was the same on average between the groups. Or maybe the low carb group exercised more and the difference in weight loss is from the exercise and not the diet. Additionally, they did not actually measure the calorie intake but rather relied on periodic diaries kept by the participants. If you read my prior post Why You Can’t Be Trusted you will know why this is not the most reliable of measurement choices. Again, it is assumed that any human error in reporting would be equal in both groups.
Another interesting fact to note is that the low carb group did not get into the Atkins level of carb aversion (<10% of calories) but more into the Zone level (30% of calories). I think this is because the participants self-regulated their diets and Atkins is hard to maintain for a long period of time but Zone is more reasonable.
The drawbacks of the study make it so that you shouldn’t come to any major conclusions about low-carb diets from this one study. With that said, the number of studies coming to the same conclusion is growing. When you combine the evidence across the board it all suggests that a low-carb diet is the way to go if you want to be successful with your weight loss.
The lead author was interveriewed by NPR. This excerpt is from their article:
Ludwig also found that when people stopped eating so many refined carbohydrates, they burned off about 150 more calories per day, compared to those eating a higher carb, lower fat diet.
“Too much refined carbohydrates — white bread, white rice, potato products — all the foods that crept into our diets as we’ve followed the low-fat craze has undermined our metabolism,” says Ludwig.
In other words, the high-carb, low-fat pattern of eating “caused us to become hungrier and burn off fewer calories,” he says.
What’s happening in the body when we follow this pattern of eating is still the subject of much research, but Ludwig says the thinking goes like this: Eating too many carbs can overstimulate the release of insulin and direct more calories into storage in the fat cells.
“It’s a double-whammy for weight gain,” Ludwig says. “We’ve been told for decades that if you don’t want fat on your body, don’t put fat into your body. It’s a very appealing notion, but the problem is it’s wrong.”
Source: Ann Intern Med. 2014;161(5):309-318