Triglycerides are among the most common lipids found in the body and compromise approximately 95% of dietary fat. Both produced by the body and absorbed from foods, triglycerides are used mainly for energy. Calories ingested that are not used immediately by tissues are converted to triglycerides and transported to fat cells to be stored. Common lack of exercise allows the triglycerides to settle within the fat cells, accumulating over time allowing the production of fat.
"Triglyceride levels rise dramatically after eating, especially after consuming simple carbohydrates, such as sugar or alcohol. This is because any sugars that are not used immediately as energy are converted to triglycerides and are stored as body fat," said senior author Mark Friedman, PhD, a behavioral physiologist at Monell. "The release of stored triglycerides is regulated by hormones, depending on the body’s energy needs. Fasting will stimulate the release of stored triglycerides."
According to new research from the Monell Center, the degree of change in blood triglyceride levels following a fatty meal may indicate susceptibility to diet-induced obesity. These findings offer practical methodology for identifying people, including children, who are at risk for becoming obese.
Triglycerides are formed from a single molecule of glycerol, combined with three fatty acids on each of the OH groups. Ester bonds form between each fatty acid and the glycerol molecule. This is where the enzyme pancreatic lipase acts, hydrolysing the bond and ‘releasing’ the fatty acid.
Triglycerides are essential for good health when present in normal amounts but high levels may be a consequence of other diseases such as untreated diabetes, aetherosclerosis, and may lead to a heightened risk of heart disease and stroke.
Like cholesterol, increases in triglyceride levels can be detected by plasma measurements. High triglyceride levels are also associated with known risk factors for heart disease, such as low levels of HDL (“good”) cholesterol, high levels of LDL ("bad") cholesterol and obesity.
In the study, Friedman and lead author Hong Ji, PhD, screened rats for vulnerability to diet-induced obesity by measuring the increase in blood triglyceride levels following a single high-fat meal. The rats were continued on a high-fat diet for the remaining of the study, and researchers were able to predict which animals would become obese over the four-week period. By studying the earlier metabolic responses, they accompanied the smaller triglyceride change with greater weight gained.
"These findings [to be published in the International Journal of Obesity] suggest we may someday be able to use a simple blood test to identify those at risk for obesity," said Friedman.
Although there currently are no simple biomarkers confirming diet-induced obesity, Friedman is confident in his study to promote future use of this type of testing. A change in blood triglyceride levels may someday successful prediction of future weight gain in humans.
"The differences in weight gain associated with high-fat diets indicate that genetically-determined factors contribute to obesity," notes Friedman. "We have shown that these genetic factors are related to the body's ability to burn fat. We now need a better understanding of how this relates to blood triglyceride levels."