Bread and other carbohydrate-rich foods, which have long served as dietary staples across cultures, may contribute to weight gain in ways that are not directly linked to increased calorie intake.

A recent study conducted by researchers at Osaka Metropolitan University offers new insights into how carbohydrates influence metabolism and body weight.

In this study, mice were given access to both standard food and carbohydrate-rich alternatives such as bread, wheat flour, and rice flour.

The results showed that the animals, which strongly preferred these carbohydrate sources, abandoned their regular diet almost entirely.

Interestingly, although their total caloric intake did not rise significantly, their body weight and fat mass increased noticeably, suggesting that factors beyond calorie consumption were at work.

Further investigation revealed that the key mechanism lies in energy expenditure. Using respiratory gas analysis, researchers found that the mice, whose diets were dominated by carbohydrates, burned less energy overall.

This reduction in metabolic rate, which created an imbalance between energy intake and expenditure, appears to have driven weight gain despite stable calorie levels.

In addition, biological changes were observed at the molecular level.

The mice exhibited higher levels of fatty acids in the bloodstream, along with reduced essential amino acids, while their livers showed increased fat accumulation and enhanced activity of genes associated with lipid production and transport.

Importantly, when carbohydrate-heavy components such as wheat flour were removed, both body weight and metabolic abnormalities improved rapidly.

This finding, which highlights the reversibility of these effects, suggests that a more balanced diet may help regulate metabolism more effectively.

Although these results are based on animal models, researchers emphasize that future studies, which will focus on human subjects, are needed to determine how these metabolic responses translate into real-world dietary patterns.