Fructose is a type of sugar commonly found in fruits, vegetables, and processed foods. Unlike glucose, fructose does not stimulate the release of insulin from the pancreas when consumed in moderate amounts (Tappy & Mittendorfer, 2012). However, consuming excessive amounts of fructose, particularly in the form of high-fructose corn syrup (HFCS), has been associated with insulin resistance, which occurs when cells become less responsive to the effects of insulin (Bray et al., 2004). This, in turn, can lead to increased insulin levels in the bloodstream, as the body tries to compensate for the insulin resistance (Johnson et al., 2007).
Increased insulin levels can promote weight gain by promoting the storage of fat in adipose tissue and by reducing the breakdown of fat in adipose tissue (Kahn & Flier, 2000). Insulin also promotes the uptake of glucose by cells, which can lead to lower blood glucose levels and increased hunger (Kahn & Flier, 2000).
In addition, consuming excessive amounts of fructose can lead to an increase in the production of triglycerides, which are a type of fat that can accumulate in the liver and contribute to the development of fatty liver disease (Basciano et al., 2005). Fatty liver disease has been linked to insulin resistance and an increased risk of type 2 diabetes (Targher et al., 2007).
Overall, while fructose itself may not directly increase insulin levels, consuming excessive amounts of fructose can contribute to insulin resistance and increased insulin levels, which can promote weight gain and increase the risk of metabolic diseases. Therefore, it is important to consume fructose in moderation as part of a balanced diet.
References:
Basciano, H., Federico, L., & Adeli, K. (2005). Fructose, insulin resistance, and metabolic dyslipidemia. Nutrition & metabolism, 2(1), 5.
Bray, G. A., Nielsen, S. J., & Popkin, B. M. (2004). Consumption of high-fructose corn syrup in beverages may play a role in the epidemic of obesity. The American Journal of Clinical Nutrition, 79(4), 537-543.
Johnson, R. J., Segal, M. S., Sautin, Y., Nakagawa, T., Feig, D. I., Kang, D. H., … & Gersch, M. S. (2007). Potential role of sugar (fructose) in the epidemic of hypertension, obesity and the metabolic syndrome, diabetes, kidney disease, and cardiovascular disease. American Journal of Clinical Nutrition, 86(4), 899-906.
Kahn, B. B., & Flier, J. S. (2000). Obesity and insulin resistance. Journal of Clinical Investigation, 106(4), 473-481.
Tappy, L., & Mittendorfer, B. (2012). Fructose toxicity: is the science ready for public health actions? Current Opinion in Clinical Nutrition and Metabolic Care, 15(4), 357-361.
Targher, G., Bertolini, L., Padovani, R., Rodella, S., Zoppini, G., Zenari, L., & Falezza, G. (2007). Prevalence of nonalcoholic fatty liver disease and its association with cardiovascular disease among type 2 diabetic patients. Diabetes Care, 30(5), 1212-1218