When you’re trying to lose weight, it’s almost impossible to bite into a rice cake without being offered diet advice: Cut carbs, limit fat, drink shakes, you name it. Is one approach better than another? Christopher Gardner, PhD, a professor of medicine at Stanford University, wanted to find out. You might be surprised to hear that the quality of your calories matters.
LOW CALORIE VERSUS LOW CARB
Research published in JAMA compared the effectiveness of low-carb and low-fat diets for weight loss. Researchers followed 609 overweight adults for 12 months and discovered that, on average, dieters in both groups lost similar amounts of weight: Those following a low-fat diet lost 11.7 pounds while those following a low-carb diet lost 13.2 pounds.
“There isn’t one diet for everyone.”
Within the groups, there were significant differences in how participants fared on each diet: Some dieters lost as much as 60 pounds while others gained weight, leading Gardner to explain, “There isn’t one diet for everyone.”
Although prescribing a specific diet might not be effective for weight loss, the research revealed some important information.
AN ALTERNATIVE METHOD: QUALITY NUTRITION
Participants were not asked to consume a specific number of calories, but all were asked to lower their fat or carb intake (depending on their group), choose more whole foods, including vegetables, and minimize added sugars and refined grains. Those who followed that advice, focusing on the quality of the calories they consumed over the quantity, lost significant amounts of weight — regardless of whether their diets were low-carb or low-fat.
“Steel-cut oats and kale are both low-fat; so are sodas and white bread, but the oats and kale are likely more filling, more satiating. Avocados and nuts are both low-carb; so are lard and butter, but meals made with avocados and nuts may be more filling, more satiating,” Gardner explains.
Focusing on healthier, more satiating foods helped dieters feel full while eating less.
An earlier JAMA study reported similar results. In 2012, 21 overweight adults were assigned to follow one of three diets: low-fat, low-carb or low-glycemic index for four weeks. Participants were instructed to replace grains and starches with vegetables, legumes, fruits and healthy fats. All dieters lost weight, but those who chose fewer carbs and ate more high-quality calories sped up their metabolisms, too, burning an additional 325 calories per day — about the same number of calories burned during an hour of moderate-intensity physical activity.
“The quality of the foods we eat can have fundamental effects on hormones, metabolism and even the expression of genes throughout the body.”
“The type of calories we consume affects the number of calories being burned. In other words, from a metabolic perspective, all calories are not alike to the body,” explains Dr. David S. Ludwig, co-director of the New Balance Foundation Obesity Prevention Center at Boston Children’s Hospital. “The quality of the foods we eat can have fundamental effects on hormones, metabolism and even the expression of genes throughout the body.”
READ MORE > THE NOT-SO-SECRET KEY TO WEIGHT-LOSS MAINTENANCE
Of course, the number of calories you consume still matters but Gardner believes it’s more important for people to choose foods that make them feel full and satisfied rather than obsessing over hitting a certain number of calories.
So, yes, [losing weight] involves eating fewer calories, but it isn’t as simple as eat less (and not as depressing either),” he says. “We would consider these quality components to be foundational to any kind of diet or eating pattern … whether they are trying out low-fat, low-carb, paleo, vegan, Mediterranean [or another diet]. It’s about finding the combinations of low-fat or low-carb meals and menus that you enjoyed and could enjoy for life that support weight goals.”
Originally published April 2018, updated August 2023
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