Recent study adds weight to the low-carb vs. low-fat debate

By American Heart Association News

James Driscoll photo

James Driscoll described himself 14 years ago as “happily married – and fat.”

At 212 pounds, the now 48-year-old from Austin, Texas, wasn’t healthy and he wasn’t happy with the way he looked. He kick started his weight-loss journey with a daily exercise routine and a popular low-carbohydrate diet. He ate more protein and eliminated carbohydrates like bread, pasta and grains. He lost 50 pounds in about seven months. But the low-carb lifestyle was hard to sustain.

Once he returned to his pre-diet habits, he bounced around with weight gain and weight loss, a pattern he would maintain for the next 10 years. His wake up call was at a checkup in 2013 when his doctor told him he might need to start statins to help lower his cholesterol.

With his doctor’s guidance, he decided to improve his diet and exercise more. After some research, he also switched to a low-fat vegetarian diet. He dropped the remaining weight he’d struggled to keep off. And he saw significant improvements in his cholesterol levels. “All my cholesterol numbers went into the normal ranges for the first time in my life,” he said.

“I’ve done the [low-carb] thing to success, as well as a low-fat diet which has helped me maintain a certain weight for over a year combined with lots of cardio.”

Meanwhile, Melissa Czarnecki, a 42-year-old from Burke, Virginia., struggled with her weight for many years, especially after her mother’s death in 2011. She amped up her exercise and ate a modified low-carbohydrate diet, involving whole, unprocessed carbohydrates, such as oatmeal and quinoa. She’s lost more than 40 pounds, lowered her blood pressure by more than 30 points and is training for a triathlon.

“It’s about eating food that’s good for you,” she said. “My taste buds have permanently changed. I don’t crave garbage anymore.” Americans spend billions of dollars each year on diets. There are diets to fit any lifestyle, interest or favorite food. Traditionally, those diets have fallen into two major camps: low-fat vs low-carb. Most low-fat diets put an emphasis on eating lean protein and dairy, fruits, vegetables and breads and starches like potatoes, rice, bread and pasta. Low-carb diet are higher in protein and fats like butter, cheese and whole fat dairy products, with limited to no breads and starches.

A new study published recently in the Annals of Internal Medicine is providing more weight to the low-carb vs low-fat debate. The study of 148 men and women was conducted over a full year; one group was given a low-carbohydrate diet, the other a low-fat diet. The study concluded that a low-carbohydrate diet was more effective for weight loss and cardiovascular risk factor reduction than a low-fat diet.

Some experts point out that despite the compelling results from this study around weight loss, other factors need to be considered before recommending one type of diet over another.

“The weight loss data are impressive but there are no significant differences among other risk factors like cholesterol and blood pressure,” said Linda Van Horn, Ph.D., professor for preventive medicine at Northwestern University Feinberg School of Medicine in Chicago and a member of the American Heart Association’s Nutrition Committee. “We can’t necessarily conclude that these results conferred important impact on decreasing risk factors for cardiovascular disease. One study does not a conclusion make.”

Van Horn also shared similar concerns regarding what Driscoll reported with his low-carb diet.

“I question the capacity of participants to continue a low-carb diet long term,” she said. “Twelve months is not a long enough time to evaluate whether people can sustain weight loss. Did participants quit the study and gain the weight back because they resumed eating cornflakes for breakfast?” Van Horn pointed to results of a second study, also published in recent weeks.

The study from the Journal of the American Medical Association analyzed data from nearly 50 other studies and found the type of diet really doesn’t make a difference in weight loss.

“It doesn’t matter what you stick with, what matters is successful long-term weight loss,” Van Horn said. “Weight control is a different factor than weight goal. The ultimate victory is long-term weight control.”

The American Heart Association doesn’t endorse a particular diet for weight loss, but instead recommends healthcare providers develop individualized weight loss plans that include three key components – a moderately reduced calorie diet, a program of increased physical activity and the use of behavioral strategies to help patients achieve and maintain a healthy body weight.

“There’s a misperception that the American Heart Association supports a low-fat diet,” said Rachel Johnson, PhD, MPH, RD, professor of nutrition at the University of Vermont and immediate past-chair of the American Heart Association’s Nutrition Committee. “We’re not saying anymore that a low-fat diet is the answer. We recommend moderate fat with a focus on healthy fats and your choices around carbohydrates need to be focused.”

This means limiting added sugars and refined carbohydrates. In the past 10 years the organization has placed a large emphasis on limiting added sugars in diet. “The science has evolved, and eating a lot of calories from added sugars is harmful to your cardiovascular health,” Johnson said. “Added sugars from sugar-sweetened beverages pose a higher risk for being overweight and developing obesity.”

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