Can a low-carb diet improve heart health?
Written by award-winning health journalist Anahad O’Connor, the article summarizes the findings of a recent landmark randomized study on diet and heart disease, published in The Journal of Clinical Nutrition.
Writes O’Connor: “[A] new study, one of the largest and most rigorous trials of the subject to date, suggests that eating a diet low in carbohydrates and higher in fats may be beneficial for your cardiovascular health if you are overweight.”
The New York Times: Can a low-carb diet help your heart health?
American Journal of Clinical Nutrition: Effects of a low-carbohydrate diet on insulin-resistant dyslipoproteinemia – a randomized controlled feeding trial
Dr. Bret Scher, a cardiologist and Diet Doctor’s Medical Director, has also summarized the influential study, which was led by Harvard professor Dr. David Ludwig. You can see Dr. Scher’s video report on the findings in the video above — or by visiting the Diet Doctor Youtube channel.
Says Dr. Scher: “This study helps us see that saturated fat is not inherently bad, especially in the context of a low-carb diet. In this case, the higher saturated fat group had greater improvements in metabolic health and cardiovascular risk factors. That is contrary to traditional thinking, and further highlights how it is time to rethink our stance against saturated fats. Context matters, baseline diet matters, and the quality of the science matters.
In his article, O’Connor described for the lay reader the study’s unique and powerful design:
“The new study included 164 overweight and obese adults, mostly women, and took part in two phases. First, the participants were put on strict, low-calorie diets that lowered their body weights by about 12 percent. Then they were each assigned to follow one of three diets in which 20 percent, 40 percent or 60 percent of their calories came from carbohydrates.
Protein was kept steady at 20 percent of calories in each diet, with the remaining calories coming from fat. The participants were fed just enough calories to keep their weights stable. The participants followed the eating plans for five months, with all of their meals provided to ensure that they stuck to their diets.”
The findings? Overweight and obese people who increased their fat intake, lowered the amount of refined carbohydrates, and kept protein levels stable and adequate had “striking improvements in a variety of metabolic disease risk factors.”
O’Connor’s article quotes Dr. Dariush Mozaffarian, a cardiologist and dean of the Friedman School of Nutrition Science and Policy at Tufts University, who was not involved with the research.
“I think this is an important study,” Mozaffarian said. “Most Americans still believe that low-fat foods are healthier for them, and this trial shows that at least for these outcomes, the high-fat, low-carb group did better.”
O’Connor notes that the average American eats at least 50% of their calories in the form of carbs, but the researchers designed diets that they considered to be healthy and practical for all three groups. Writes O’Connor:
All of the participants ate meals like vegetable omelets, chicken burritos with black beans, seasoned London broil, vegetarian chili, cauliflower soup, toasted lentil salads, and grilled salmon. But the high-carb group also ate foods like whole-wheat bread, brown rice, multigrain English muffins, strawberry jam, pasta, skim milk, and vanilla yogurt. The low-carb group skipped the bread, rice and fruit spreads, and sugary yogurts. Instead, their meals contained more high-fat ingredients such as whole milk, cream, butter, guacamole, olive oil, almonds, peanuts, pecans and macadamia nuts, and soft cheeses.
After five months, the low-carb, higher fat group had experienced no detrimental effects on their cholesterol, despite getting 21% of their calories from saturated fat. And they saw “striking improvements” in a wide variety of other markers of metabolic health.
In the high-carb arm of the trial, participants saw risk factors for diabetes increase during the study.
Do you want to try a low-carb diet?