Overeating Is Not What’s Causing You to Gain Weight — This Is the True Culprit

It’s not hard to understand why people gain weight, right? If we consume more calories than we burn, we’ll put on pounds. Want to slim down? Eat less and move more. It’s what we’ve heard for years, but researchers recently offered a new perspective that turns that thinking on its head. Could it be that overeating doesn’t actually cause weight gain?

Dr. David Ludwig, an endocrinologist at Boston Children’s Hospital and professor at Harvard Medical School, co-authored an article published this month in The American Journal of Clinical Nutrition that challenges the prevailing wisdom about what’s behind the obesity epidemic in this country.

According to the article, which was co-authored by a team of 17 internationally recognized scientists, clinical researchers, and public health experts, it’s what we eat, rather than how much, that has the biggest impact on our weight.

More than 40 percent of Americans are obese (defined as having a Body Mass Index, or BMI, of 30 or above). Obesity puts people at a higher risk of heart disease, stroke, diabetes, and even certain types of cancer. That’s why finding the root cause of weight gain, and helping people figure out how to more effectively manage their weight, is so important.

Do we need to rethink traditional weight loss advice?

The weight loss advice most of us have heard for years follows the “energy balance model,” which is the calories-in-calories-out thinking that says overeating, along with a lack of adequate physical activity, causes people to gain weight.

However, Ludwig proposes a new perspective, the “carbohydrate-insulin model,” which explains obesity as a metabolic disorder triggered by overeating the wrong kinds of foods, rather than by overeating itself. “Conceptualizing obesity as a disorder of energy balance restates a principle of physics without considering the biological mechanisms underlying weight gain,” he says.

While the USDA’s Dietary Guidelines for Americans 2020-2025 states that in order to nudge the number on the scale downward, “adults [need] to reduce the number of calories they get from foods and beverages and increase the amount expended through physical activity,” Ludwig says we’d be better served by taking a closer look at our daily diet and reducing the amount of processed carbohydrates we eat and drink.

Can you eat as much as you want and still lose weight?

Foods with a high glycemic load — in particular, processed carbohydrates such as pastries, pizza, packaged pasta (unless it’s whole grain), breakfast cereal, white bread, and white rice — cause hormonal responses that fundamentally change our metabolism, according to this new way of thinking. And it’s this change in metabolic rate that’s the real culprit behind weight gain and obesity.

So what does this mean for someone trying to drop a few pounds? “Reducing consumption of the rapidly digestible carbohydrates that flooded the food supply during the low-fat diet era lessens the underlying drive to store body fat,” says Ludwig. “As a result, people may lose weight with less hunger and struggle.”

In other words, overeating isn’t something to worry about if you’re eating the right kinds of foods. Want to fit into your pre-pandemic skinny jeans without feeling deprived and grouchy? Just skip the packaged “low calorie” foods and anything made with white flour or refined sugar. Instead, reach for whole grains, fruits, and vegetables. That way, you can feel good about helping yourself to seconds, thirds, and even fourths.

To that, we say bon appétit!