Which Is Better: Low-Carb or Low-Fat? Neither, New Research Suggests
If you’re looking to lose weight, taking these extremes may not be as successful as another approach altogether.
Tell people you’re going on a diet, and the inevitable question pops up: Are you going low-carb or low-fat?
Maybe you had trouble making the choice yourself when you determined you wanted to lose weight. After all, there hasn’t been a clear answer on what diet works best — and for whom.
But a new study attempts to shed some light on that question.
The research, published in February 2018 in the journal JAMA, found that people following either a low-fat or low-carb diet lost just about the same amount of weight — 11.6 and 13.2 pounds, respectively — after one year. Researchers say this difference isn’t significant, so what gives?
RELATED: 10 Popular Low-Carb Diets, and Their Pros and Cons
How Exactly Was the Research Conducted?
Scientists recruited 609 healthy, overweight, or obese middle-aged men and women for the study. Over the year, each participant attended 22 registered dietitian–led sessions aimed at teaching them a healthy way to eat low-fat or low-carb, depending on what group they were in (because you can, essentially, make unhealthy choices in each category).
Each participant started by limiting fat and carbs to 20 grams per day over the first two months. After that, they added fat or carbohydrates back into their diet in small amounts until they got to a level they felt was sustainable.
RELATED: What Are the Benefits and Risks of the High-Fat, Low-Carb Keto Diet?
Why the Findings Matter if You’re Looking to Lose Weight
The similar weight loss between the groups isn’t the only story.
Because past studies have shown that people lose vastly different amounts of weight on various diets — and no one diet works for everyone — researchers set out to see if someone’s genetic makeup or insulin secretion could predict dieting success.
"We were trying to determine if we could explain the massive variability in response within each diet, rather than trying to find whether one diet was 'the' best diet," says lead study author Christopher Gardner, PhD, a professor of medicine at Stanford University in California.
The findings? Neither genetics nor insulin secretion made a difference in the outcome.
The interesting thing about the study was how researchers advised participants to eat. While it seems like low-fat and low-carb are two vastly different eating approaches, participants were anchored by common goals: eating more veggies, and cutting back on added sugar, refined flour, and trans fat.
Diet quality was also emphasized, including choosing minimally processed food and encouraging cooking at home.
While the groups weren’t told how many calories they should eat, each person shaved off 500 to 600 calories per day.
RELATED: What's the Difference Between Atkins and Keto?
Given that each person more or less customized his or her own eating plan by adjusting fat and carb intake, the findings appear to be more evidence for the idea that what works for one person won't for another — there are a multitude of factors that go into weight loss (personality, habits and behaviors, and lifestyle, for instance), Dr. Gardner says. There's no one perfect diet for everyone.
"For now, I suspect 'tinkering' [adjusting your intake based on preferences] with your food is as likely or more to work than someone's claim for a genotype or metabolic type that predisposes you [to a certain diet]," Gardner says.
RELATED: 5 Tricks for Getting Enough Fruit and Veggies
The Weight Loss Insight You Should Take Away From the Study Results
So, why did this eating approach work for the participants?
Nutrition counseling and education from registered dietitians likely played an important role, says Samantha Heller, RDN, senior clinical nutritionist at NYU Langone Medical Center in New York City, who was not involved in the study.
Heller notes that the study supports what she sees anecdotally in her practice — that people overall are more likely to lose weight when they get guidance and help from professionals. “They need support, instruction, and ideas on how to implement these strategies,” she says.
Heller also points out that the study emphasized choosing high-quality foods, which may be another reason behind participants’ success, rather than the specific diet. “When you improve the overall quality of your diet, you tend to cut calories and lose weight,” Heller adds.
And that, essentially, is a far simpler message compared with adopting a specific diet that may or may not work for you. Rather than going on a low-fat or low-carb diet, Heller recommends choosing an eating plan — not a diet — that is balanced, healthy, sustainable, and mostly plant-based.
RELATED: The Best and Worst Diet Plans for Heart Health, Weight Loss, and More
The three that tend to promote wellness and a healthy weight, she says, are the Mediterranean diet, the DASH diet, and the vegetarian diet. Their commonalities include emphasizing produce, whole grains, nuts and beans, healthy fats, and some lean protein.
“It’s not a sexy, intense, or extreme message,” Heller says. “But we see that people who adopt these types of eating patterns tend to be a healthier weight.”