Osaka Metropolitan University Study Links High Carbohydrate Preference to Reduced Energy Expenditure and Weight Gain

Osaka Metropolitan University study finds that a strong preference for bread and rice leads to weight gain by slowing down metabolic energy expenditure.

By: AXL Media

Published: Apr 14, 2026, 7:52 AM EDT

Source: Information for this report was sourced from EurekAlert

Shifting the Focus of Obesity Research

While traditional obesity research has primarily investigated excessive fat consumption as the leading cause of weight gain, carbohydrates remain a daily staple for much of the global population. Researchers at Osaka Metropolitan University’s Graduate School of Human Life and Ecology recently pivoted this focus to examine how staples like bread, wheat, and rice affect metabolism. Published in Molecular Nutrition & Food Research, the study suggests that the common perception of carbohydrates causing weight gain may be rooted in metabolic shifts triggered by a strong dietary preference for these foods over standard nutritional sources.

Preference and Metabolic Consequences

Led by Professor Shigenobu Matsumura, the team established several feeding groups for mice, offering choices between standard chow, bread, wheat flour, and rice flour. The results showed a powerful behavioral preference for carbohydrates, with the subjects altogether abandoning their standard chow when presented with wheat or rice alternatives. Under these conditions, the subjects experienced a significant increase in body weight and fat mass. Notably, this occurred despite the fact that the total caloric intake did not increase significantly, indicating that the source of the calories played a more critical role than the quantity alone.

The Role of Energy Expenditure

To determine the cause of weight gain, the researchers utilized indirect calorimetry through respiratory gas analysis. This method revealed that the increase in weight was not the result of overeating, but rather a measurable decrease in energy expenditure. The metabolic shift suggest that high carbohydrate intake may signal the body to conserve energy rather than burn it. Interestingly, mice that were fed a high-fat diet combined with wheat flour actually exhibited less weight gain compared to those on a high-fat diet with standard chow, suggesting complex interactions between different macronutrients.