(Posted Fri. Jan 4th, 2013)
Jan. 4: A new “exploratory” study in the Journal of the American Medical Association makes provocative claims about the effects of fructose on hunger and weight gain, but bases its conclusions on a test conducted on just 20 people who were fed massive doses of sugars in a manner that people do not consume in real life.
“It is highly unusual for humans to consume this much sugar in one sitting, particularly if they had just finished a fast,” said Dr. James Rippe, Founder and Director of the Rippe Lifestyle Institute and professor of Biomedical Sciences at the University of Central Florida. “All of these factors could certainly alter the eventual outcomes. It is important that studies focusing on obesity and food consumption mirror real world experiences as much as possible. By failing to do so, we really gain very little practical insight.”
The study, “Effects of fructose versus glucose on regional cerebral blood flow in brain regions involved with appetite and reward pathways,” attempts to demonstrate a link by giving the subjects either large doses of fructose or large doses of glucose and comparing cerebral blood flow and activity in regions of the brain that regulate appetite. However, neither of these sugars is consumed in any appreciable degree in isolation in the human diet as they are almost always consumed together.
“When consumed together, as they are almost always are, fructose and glucose balance each other out and would likely have no effect on normal hypothalamic blood flow,” said Dr. Rippe, who is also a consultant to the Corn Refiners Association. “What we really need are real world studies where fructose and glucose are consumed together rather than artificial ones where fructose and glucose are consumed separately. Any suggestion that this artificial experiment has implications for human nutrition or obesity is unwarranted speculation.”
Also, the amount of fructose or glucose each group received was well beyond the amount normally consumed. Each subject was given 75 grams of either fructose or glucose in one sitting. 75 grams of fructose represents 300 kcals of fructose which is above the 95 percentile population level recommended for the entire day. Furthermore, each of the subjects had fasted overnight before receiving the fructose or glucose.