Effect of Meal Size on Absorption

When a meal of mixed macronutrient composition is consumed, the rate at which the carbohydrate, protein, and fat in that meal is absorbed differs. Carbohydrate in the form of glucose and protein in the form of amino acids enter the portal vein within 30 minutes of meal ingestion and later appear in the general circulation. As the glucose concentration in the portal vein increases, there is an increase in the uptake of glucose into the hepatocytes. Pancreatic islet cells react to the increase in blood glucose and secrete insulin, among other hormones, into the circulation. As a result, there is a decline in the release of none-sterified fatty acids from the adipose tissue. Fatty acid oxidation in the skeletal muscle tissue decreases, and as glucose uptake takes place, the muscle cells increase the rate at which glucose is oxidized. Glycogen synthesis in the muscle and liver cells is increased and the uptake of amino acids by muscle tissue may also occur. Up to 4 h after ingestion of the meal, fat in the form of chylomicron triacylglycerol enters the circulation via the lymphatic system. The action of the hormone lipoprotein lipase in the adipose tissue has by now increased, which promotes the storage of fatty acids as triacylglycerol in adipocytes. This synopsis indicates that following the ingestion of a meal, there is a marked increase in glucose oxidation with a corresponding decrease in fat utilization resulting in the storage of fat.

The larger the meal consumed, the more pronounced are the responses described previously. After a large meal is eaten, the plasma glucose concentration will remain elevated for up to 4 h following ingestion. Conversely, the smaller the meal, the more subtle the effect. This indicates that meal size does indeed influence absorption. However, in order for the relationship between meal size and absorption to be fully understood, the role that absorption plays in determining meal size needs to be considered. The following section focuses on the process of absorption and the systems that control the amount of food eaten.

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Supplements For Diabetics

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