Research published in JAMA (The Journal of American Medical Association) supports the idea that diet quality, not quantity, is what helps people lose and manage their weight most easily in the long run.
Eat what you want as long as it’s good for you
The research published in JAMA found that people who cut back on added sugar, refined grains and highly processed foods and instead ate plenty of vegetables and whole foods, were able to lose significant amounts of weight — even without limiting portion sizes.
The research lends strong support to the notion that diet quality, not quantity, is what helps people lose and manage their weight most easily in the long run.
The strategy worked for people whether they followed diets that were mostly low in fat or mostly low in carbohydrates. And their success did not appear to be influenced by their genetics or their insulin-response to carbohydrates. This is a finding that casts doubt on the increasingly popular idea that different diets should be recommended to people based on their DNA makeup or their tolerance for carbs or fat.
The research suggests that health authorities should shift away from telling people to obsess over calories and instead encourage Americans to avoid processed foods that are made with refined starches and added sugar, like bagels, white bread, refined flour and sugary snacks and beverages.
“This is the road map to reducing the obesity epidemic in the United States,” said Dr. Dariush Mozaffarian, a cardiologist and dean of the Friedman School of Nutrition Science and Policy at Tufts University who was not involved in the new study. “It’s time for U.S. and other national policies to stop focusing on calories and calorie counting.”
How the study was conducted
The research was led by Christopher D. Gardner, the director of nutrition studies at the Stanford Prevention Research Center and carried out on adults recruited from the Bay Area.
It was a large trial, carried out on more than 600 people with funding from the National Institutes of Health, the Nutrition Science Initiative and other groups.
Dr. Gardner and his colleagues designed the study to compare how overweight and obese people would fare on low-carb and low-fat diets.
The research also wanted to test the hypothesis suggested by previous studies — that some people are predisposed to do better on one diet over the other depending on their genetics and their ability to metabolize carbs and fat.
Sometimes when I indulge and gain a few pounds I think “I’m genetically prone to gain weight and have low metabolism.” That’s why this hypothesis interested me.
Healthy low carb and healthy low fat
The researchers recruited adults from the Bay Area and split them into two diet groups that were called “healthy low carb” and “healthy low fat”.
Low fat: The low-fat group was told to avoid soft drinks, fruit juice, muffins, white rice and white bread that are technically low in fat. They were told instead to eat foods like brown rice, barley, steel-cut oats, lentils, lean meats, low-fat dairy products, quinoa, fresh fruit and legumes.
Low carb: The low-carb group was trained to choose nutritious foods like olive oil, salmon, avocados, hard cheeses, vegetables, nut butters, nuts and seeds, and grass-fed and pasture-raised animal foods.
Members of both groups attended classes with dietitians where they learnt to eat nutrient-dense, minimally processed whole foods, cooked at home whenever possible. In classes with dietitians most of the time was spent discussing food and behavioral strategies to support their dietary changes.
The participants were encouraged to meet the federal guidelines for physical activity but did not generally increase their exercise levels.
Emphasize on eating whole foods with no limits on quantity
The new study stands apart from many previous weight-loss trials because it did not set extremely restrictive carbohydrate, fat or caloric limits on people and emphasized that they focus on eating whole or “real” foods — as much as they needed to avoid feeling hungry.
“The unique thing is that we didn’t ever set a number for them to follow. We really stressed to both groups again and again that we wanted them to eat high-quality foods.
We told them all that we wanted them to minimize added sugar and refined grains and eat more vegetables and whole foods.
We said, ‘Don’t go out and buy a low-fat brownie just because it says low fat or those low-carb chips — don’t buy them; because they’re still chips and that’s gaming the system.’” Dr. Gardner
Dr. Gardner said many of the people in the study were surprised — and relieved — that they did not have to restrict or even think about calories.
“A couple weeks into the study people were asking when we were going to tell them how many calories to cut back on,” he said. “And months into the study they said, ‘Thank you! We’ve had to do that so many times in the past.’”
Calorie counting not optimal
Calorie counting has long been ingrained in the prevailing nutrition and weight loss advice. The Centers for Disease Control and Prevention, for example tells people who are trying to lose weight to “write down the foods they eat, the beverages they drink, plus the calories they have each day. With the goal of restricting the amount of calories they eat and increasing the amount of calories they burn through physical activity. “Weight management is all about balancing the number of calories you take in with the calories your body burns off.” the agency reccomends.
Yet the new study found that after one year of focusing on food quality, not calorie counting, both groups lost substantial amounts of weight.
On average, members of the low-carb group lost over 13 pounds, while those in the low-fat group lost about 11.7 pounds.
Both groups also saw improvements in other health markers such as reductions in their waist sizes, body fat, low blood sugar and normal blood pressure levels.
How the data was analyzed
Researchers took DNA samples from each subject and analyzed a group of genetic variants that influence fat and carbohydrate metabolism.
But ultimately the subjects’ genotypes did not appear to influence their responses to the diets.
“The bottom line: Diet quality is important for both weight control and long-term well-being,” Dr. Gardner
Dr. Gardner said it is not that calories don’t matter. After all, both groups ultimately ended up consuming fewer calories on average by the end of the study, even though they were not conscious of it. The point is that they did this by focusing on nutritious whole foods that satisfied their hunger.
“I think one place we go wrong is telling people to figure out how many calories they eat and then telling them to cut back on 500 calories, which makes them miserable. We really need to focus on foundational diet, which is more vegetables, more whole foods, less added sugar and less refined grains.”
Bottom Line: It’s not about eating more or less carbs, but more about eating healthy carbs and fats
The most important message of the study was that a high quality diet focused on healthy fats and carbs produced substantial weight loss. Eating this way also prevents heart disease, diabetes and other diseases.