Consuming bread and other carbohydrate-rich items might lead to weight gain, even without boosting overall daily calorie intake, due to a slowing of the metabolic rate. This conclusion was reached by researchers at the Osaka Metropolitan University’s Graduate School of Human Life and Environmental Studies. News of this was published on April 14th in the journal Science Daily.
“The findings suggest that weight gain might stem not from exclusive properties of wheat, but rather from a pronounced preference for carbohydrates and the resulting metabolic shifts,” explained Professor Shigenobu Matsumura, the lead investigator.
Under Professor Matsumura’s guidance, the scientists investigated how carbohydrates affect the eating habits and metabolism of mice. The animals were split into several groups based on their diet: standard chow, standard chow supplemented with bread, wheat flour, or rice flour, a high-fat diet with added wheat flour, and various other mixes. Throughout the experiment, the researchers monitored changes in body weight, energy expenditure, blood composition, and gene expression in the liver.
The results indicated a clear favoritism among the mice for carbohydrate products, causing them to cease eating the standard feed entirely. Despite no significant rise in total caloric intake, their body mass and adipose tissue levels increased. The mice fed rice flour gained weight at the same rate as those consuming wheat flour. Conversely, animals on the high-fat diet with added wheat flour gained less weight compared to those on the high-fat diet with regular chow.
Analysis using indirect calorimetry demonstrated that the weight gain was caused by a decrease in energy expenditure, rather than overeating. Elevated levels of fatty acids and reduced concentrations of essential amino acids were detected in the animals’ blood. Fat accumulation in liver cells intensified, alongside increased activity of genes associated with fatty acid synthesis and lipid transport. Once wheat flour was removed from their diet, the mice’s body weight and metabolic indicators swiftly returned to normal.
Moving forward, the researchers intend to ascertain the degree to which these observed patterns apply to human subjects. The team plans to examine the metabolic response to whole and unprocessed grains, fiber-rich foods, the combination of carbohydrates with proteins and fats, food processing methods, and meal timing.
On March 16th, dietitian and nutritionist Roman Pristansky issued a caution regarding the risks of significantly reducing dietary fat. He emphasized that fats are the body’s most energy-dense substrate, serving crucial structural roles, participating in hormone production, and supplying the body with energy. He deemed an optimal daily intake to be between 0.5 and 1 gram per kilogram of body weight. According to Pristansky, the same principle applies to protein intake.
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