Fast Take: Takeaways from a New Study Pitting Low-Carb & Low-Fat Diets Against One Another

Highlights: 
  • New research from JAMA suggests that neither a low-carb nor a low-fat diet outweighs the other in terms of weight loss.
  • Although the findings add to the debate between different diets, there are also a few additional findings worth noting, specific to nutrient density and developing a healthy relationship with food.
  • If we focus on eating mostly nutrient-dense foods, listening to our hunger cues and redefining our relationship with food, we have some compelling tools to use in our quest for better health.

Low-carb? Low-fat? Personalized to your DNA? There’s a lot of hype about which diet, if any, is best for your long-term health. New research from JAMA may suggest that neither a low-carb nor a low-fat diet outweighs the other in terms of weight loss. What’s more, participants in this study achieved an additional goal: developing a healthy relationship with food. These findings shed light on how healthy behaviors, instead of solely focusing on weight loss, can lead to better health outcomes, so let’s take a look into the study!

Study Design and Goals

The study enrolled 609 adults aged 18 to 50 who were all overweight or obese but otherwise healthy. Participants were randomized to a low-fat or low-carbohydrate diet for one year. The study examined the effect of a healthy low-fat diet versus a healthy low-carbohydrate diet on weight change and also tested if specific genetic patterns or baseline insulin secretion were associated with weight loss. Half the group were randomly assigned to significantly decrease how many carbohydrates they ate, while the other half cut back on fat. Interestingly, participants were not advised on a specific calorie intake.

In addition to modifying their eating patterns, participants were enrolled in 22 health education classes where they were counseled on food choices and behaviors. For example, the participants were instructed to minimize their intake of sugars, refined flours and trans fats and to focus on nutrient-dense foods. They were also encouraged to adopt healthy habits like cooking at home, eating mindfully and sitting down for structured meals with family members.

The Low-Fat Low, Carb Low-Down

While individual weight changes ranged quite a bit, the average weight loss in the two groups was nearly identical: Each group lost an average of about 10 pounds. Additionally, the study did not find a relationship between genetic patterns and weight loss. This is particularly interesting, given the increasing interest in the field of personalized nutrition, which aims to provide tailored nutrition recommendations based on genetic, lifestyle and environmental factors.

There’s More to the Story

Although the findings add to the debate between different diets, there are also a few additional findings worth noting, specific to nutrient density and developing a healthy relationship with food. The study emphasized focusing on nutrient-dense foods, which are high in nutrients but relatively low in calories. Examples of nutrient-dense foods include fruits and vegetables, whole grains, low-fat or fat-free milk products, seafood, lean meats, eggs, beans and nuts.

While some of the conversation around this concept and application of nutrient density pits whole foods versus processed foods, it’s slightly off-base. Yes, participants were instructed to limit sugars, refined flours and trans fats and focus on nutrient-dense foods, but this doesn’t mean that some processed foods like frozen produce, boxed pasta, yogurt and canned beans weren’t part of their diets.

Additionally, the study did not place strict calorie restrictions on their participants (and didn’t make them feel anxious around food). They were taught key foundations of nutrition without being overly obsessive about calorie control. Emphasis was placed on eating without anxiety instead of worrying about whether the food eaten was “good enough.” Focusing on nutrient-dense foods, while allowing some room for indulgence — all without restriction — are all core components of intuitive eating. And this study showed that they can lead to significant changes in health outcomes.

Your Relationship with Food Is Relevant

This study serendipitously found that when you work to improve someone’s relationship with food, they’re less likely to overeat and may lose weight. Dr. Christopher D. Gardner, the lead researcher, told the New York Times that the people who lost the most weight reported that the study had “changed their relationship with food.” It makes sense! Focusing on mindful eating, sitting down with family to enjoy a meal and incorporating foods that make us feel energized without strictly monitoring the number of grams eaten of a given food create a more sustainable relationship with food. We know extreme diets don’t work because people aren’t meant to restrict, count and over-analyze their foods. But people might remember a cooking class they took that taught them how to prepare their own foods and filled them with joy and satisfaction at a job well done.

Healthy Behaviors Produce Better Health Outcomes

This study was not able to determine if a low-carb or low-fat diet was better for weight loss. And that’s a-OK. Dr. Gardner echoes this, stating in Time: “There isn’t any one diet that anyone has to follow.” This is good news because research shows that weight shame and extreme dieting often trigger weight gain. As this study shows, improving one’s relationship with food while also reducing anxiety or fear around food can lead to sustainable health outcomes.

If we replace the focus of weight loss with healthy behaviors, such as eating mostly nutrient-dense foods, listening to our hunger cues and not feeling guilty around food, we have some compelling tools to use in our quest for better health.

This blog includes contributions from Megan Meyer, PhD.

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