Are all calories created equal?

David Ludwig, MD, PhD Boston Children's Hospital

Historically, people who lose weight have a hard time keeping it off long-term. Most people believe it’s due to lack of adherence to diets or lost motivation, but recent research finds that not all calories are the same—and that following a low-glycemic diet that works with a person’s changing metabolism could help maintain weight loss.

Researchers Cara Ebbeling, PhD, and David Ludwig, MD, PhD, of the New Balance Foundation Obesity Prevention Center Boston Children’s Hospital considered that after people lost weight, the rate at which they burned calories slowed down, making it harder to maintain weight loss. The challenge was to find a diet that would work with the body’s changing metabolism and help people continue to burn calories at a rate that would help them maintain their weight loss.

“Keeping weight off—even under the best circumstances—is difficult,” says Ludwig. “But lining up biology and behavior can help.” Ludwig and Ebbeling studied the affects of three diets with the same amount of calories in each:

  • Low-fat, which is typically recommended by the U.S. government and American Heart Association, aims to reduce overall fat intake.
  • Low-carbohydrate, modeled after the Atkins diet, reduces almost all carbohydrate intake.
  • Low-glycemic, which aims to keep blood sugar levels steady by choosing natural foods and high-quality protein, carbohydrates and fats.

Even though all three diets consisted of the same amount of calories, the low-glycemic diet came out on top: Aside from helping to stabilize metabolism even after weight loss, existing research suggests that low-glycemic diets help people feel fuller longer and experience improved sense of well-being, as well as improved mental and physical performance.

Despite often being recommended by health organizations, the low-fat diet slowed down metabolism the most (meaning it became harder to burn calories), and while the low-carbohydrate diet didn’t hurt the metabolic rate, it negatively affected hormone levels, causing unnecessary stress and inflammation inside the body, potentially increasing the risk of heart disease. “Recommendations for low-fat diets have been based on very little evidence,” says Ludwig. “Reducing all fats can actually be counterproductive, and keeping healthy fats like nuts, olive oil and avocados in the mix can add flavor, too.”

In addition, Ludwig recommends choosing natural and unprocessed carbohydrates like barley, rye and brown rice.

Even for children who aren’t overweight, low-glycemic diets offer long-term benefits for weight maintenance, preventing excessive weight gain and general health improvements. “A low-glycemic diet offers a healthy variety without eliminating entire classes of foods—like fat or carbs—so it’s naturally more sustainable,” says Ludwig. “This is especially helpful for children, since variety and flexibility make it easier for them to follow.”

But how simple is it for an average family to consume a low-glycemic diet? “It’s pretty easy to follow, since it’s based on natural foods that keep us filled up,” says Ludwig. “Choose foods that your grandmother used to eat—ones that resemble things in nature, and don’t come with long lists of ingredients.”

Here are the basic steps for following a low-glycemic diet:

  • Eat fiber-rich, natural carbohydrates like non-starchy vegetables, fruits and legumes along with protein and healthy fat (like nuts, avocado or olive oil).
  • Eat grain products in their least-processed state possible, like stone ground whole grain bread rather than white bread.
  • When you have a sugary treat, do so only in moderation and after a balanced meal.
  • Limit fruit juice, avoid sugary soda and drink mostly water.

Ready to get started? Print out our healthy shopping list.

The Boston Children’s Hospital Optimal Weight for Life (OWL) Program offers state-of-the-art patient care for treatment of pediatric obesity, and is accepting new patients now. The multi-disciplinary, evidence based practice shows patients not how to diet, but how to eat for life.

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One thought on “Are all calories created equal?

  1. Great work! I love how you used 3 controlled diets in defined time periods.  There’s a powerful set of statistical techniques that can help quantify the effects of various diet factors (with R-squared/correlation values) called Design of Experiments.  Have you looked into their application to your research?  I would love to talk with you about how that could help you, as a former practitioner of the technique in various applications. 

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