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The order in which people eat their food may influence how sharply their blood sugar rises after a meal, with new research in mice suggesting that consuming fat before carbohydrates can help limit the spike.
The findings offer fresh insight into how meal sequencing may affect blood sugar regulation and could eventually help inform practical dietary approaches for people managing diabetes. However, the results are based on animal experiments and need to be confirmed in human studies.
Previous clinical research has suggested that eating vegetables, protein or fat before carbohydrate-rich foods can help moderate post-meal blood sugar increases. Changing the order of foods may therefore offer a practical way to support glucose control without eliminating entire food groups.
Researchers have generally attributed this effect to two mechanisms: slower movement of food from the stomach into the small intestine, known as gastric emptying, and increased release of hormones that help regulate blood sugar.
The latest study examined how these processes interact with signals from the nervous system.
“Our group has long been interested in practical dietary approaches that people can continue in everyday life,” said Daisuke Yabe of Kyoto University, the study’s corresponding author. He noted that meal sequencing is appealing because it changes how people eat rather than requiring them to avoid particular food groups.
The research team conducted experiments in mice to compare the effects of consuming fat before or after glucose.
After an overnight fast, the animals were divided into three groups. One received water followed by glucose, another received olive oil 15 minutes before glucose, and the third received glucose before olive oil.
The researchers measured blood glucose levels and several hormones involved in glucose regulation, including insulin, glucagon, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1).
They also assessed gastric emptying and conducted further experiments involving mice with type 2 diabetes, animals lacking the receptor for GLP-1, and mice whose vagus nerves had been surgically interrupted.
The vagus nerve connects the brain and digestive system, helping coordinate digestion and other bodily functions.
The results showed that mice given olive oil before glucose experienced a smaller initial rise in blood sugar than those given glucose first.
Eating fat beforehand also slowed gastric emptying, delaying the movement of glucose from the stomach into the small intestine.
The researchers observed an early increase in glucagon, GIP and GLP-1 after fat consumption. These findings suggest that the body’s response involves several interacting hormonal pathways rather than a single mechanism.
The effects were also observed in mice with type 2 diabetes and severe insulin deficiency, suggesting that the response may operate even when normal insulin regulation is significantly impaired.
One unexpected finding concerned glucagon, which is generally known for raising blood glucose by prompting the liver to release stored glucose.
Blocking glucagon signalling alone did not eliminate the benefit of consuming olive oil before glucose. Blocking GLP-1 signalling alone also failed to remove the effect.
However, blocking both pathways at the same time reduced the benefit.
The findings suggest that glucagon and GLP-1 may work together in a more complex system that helps moderate the rise in blood sugar after eating fat before carbohydrates.
Although glucagon is commonly associated with increasing blood glucose, its role in this process appears to be more complicated than previously understood.
The findings add to research exploring whether the sequence of foods during a meal can influence metabolic health. Eating vegetables and protein before carbohydrate-rich foods has already been investigated as a potential strategy for reducing post-meal glucose spikes.
However, the latest study does not establish that eating olive oil before carbohydrates will produce the same effects in humans. Further clinical research is needed to determine how meal sequencing works in people, including those with diabetes, and whether the benefits persist over time.
For now, the research highlights a promising area of dietary science rather than a proven treatment. People managing diabetes should continue to follow their prescribed treatment and dietary advice rather than relying on meal order alone to control blood sugar.