Previous studies have suggested a benefit from drinking coffee in moderation might improve weight loss and reduce the incidence of developing type 2 diabetes. New evidence has now emerged out of Australia suggesting the potential harm from coffee over-consumption may in fact reduce weight loss.
Researchers from the Western Australian Institute for Medical Research (WAIMR) and the University of Western Australia’s School of Medicine and Pharmacology determined excess consumption of chlorogenic acid (CGA), a type of polyphenol found in coffee, can reduce fat loss and exacerbate insulin resistance.
Vance Matthews, assistant professor at WAIMR and Kevin Croft, professor at Western Australia, studied the effects of chlorogenic acid in obese male mice over a 12 week period. Mice were subjected to one of three dietary interventions: 1-normal diet, 2-high-fat diet, and 3-high-fat diet with chlorogenic acid. Mice that received chlorogenic acid were given the amount of 1g/kg, relatively equivalent to the amount in 5 or 6 cups of coffee. The researchers assessed the effect of chlorogenic acid on high-fat-diet-induced obesity, glucose intolerance, insulin resistance, fatty acid oxidation and insulin signaling.
The researchers found the mice fed with the high fat diet plus chlorogenic acid did not produce a significant weight loss compared to mice on the high fat diet alone. Mice that received chlorogenic acid had significant increases in insulin resistance compared to the other dietary interventions. In mice, chlorogenic acid was noted to decrease activation of AMPK in the liver leading to decreased glucose control and higher liver lipid content indicating impaired fatty acid oxidation.
The researchers concluded that the use of chlorogenic acid in a high-fat diet does not protect against the development of the metabolic syndrome in diet-induced obese mice.
In regards to consumption of coffee by people, Matthews concluded, "It seems that the health effects are dose-dependent. A moderate intake of coffee, up to three to four cups a day still seems to decrease the risk of developing diseases such as cardiovascular disease and type 2 diabetes."
A Mubarak, JM Hodgson, MJ Considine, et al. Supplementation of a high-fat diet with chlorogenic acid is associated with insulin resistance and hepatic lipid accumulation in mice. Journal of Agricultural and Food Chemistry. 2013.