Thursday, February 23, 2012

Insulin Reduces Appetite

Along the same lines as Stephan Guyenet's recent post Insulin and Obesity: Another Nail In The Coffin, a new study published in Diabetes reports that "insulin administration might be useful in curtailing overconsumption of snacks with accentuated rewarding value."

Health Day reported on the study:

"Brain insulin may act as a satiety signal during the postprandial period and is associated with decreased appetite and reduced intake of highly palatable food, according to a study published online Feb. 16 in Diabetes.

Manfred Hallschmid, Ph.D., from the University of L├╝beck in Germany, and colleagues investigated the role of brain insulin signaling in the control of food intake. In two groups of healthy women, 160 IU insulin or vehicle were administered after lunch, and two hours later, the consumption of cookies of varying palatability was evaluated under the pretext of a taste test. Intranasal insulin was administered to fasted females as a control study.
The researchers found that, compared with placebo, insulin administration in the postprandial state, but not in the fasted state, decreased appetite along with intake and rated palatability of the most palatable snack offered. Intranasal insulin administration was associated with a small decrease in plasma glucose, but no effect on serum insulin concentration was seen.
"Postprandially administered intranasal insulin enhances the satiating effect of meals and reduces palatable snack intake, suggesting that insulin acts as a relevant signal in the short-term regulation of satiety in humans," the authors write. "Considering that the rewarding effect of palatable food overriding the homeostatic control of energy intake may promote obesity, insulin's potential to curb the appetite for hedonically salient, calorie-rich food deserves particular attention."
This study suggests that building meals around low-energy density foods that significantly raise insulin levels, such as potatoes, rice, and the like, could curb appetite for highly palatable snacks.

It also suggests inversely that eating meals that minimize insulin release might result in less post-meal satiety and increased appetite for snacks. 

Perhaps this provides partial explanation for the low prevalence of obesity in nations like Japan, where the cuisine revolves around a highly insulinogenic starch like white rice.


LeonRover said...

I wonder how Dr Richard K Bernstein might incorporate nasal insulin spray into his treatment of Type 1 and Type 2 diabetics?

Gretchen said...

Don, 160 units of insulin would put most people into a coma. It's important to stress that this was *intranasal* insulin.

Suzanne Craft is using intranasal insulin to treat Alzheimer's, with some success.

Renaud said...

72% fat, 22% carbohydrate, and 6% protein compared with control meal (no fat at all).

High fat seems to be a good way to boost insulin response.

Will said...

Hi Renaud,

That study is interesting. People on the control meal clearly had the lowest postprandial insulin response. Yet all meals yielded similar postprandial glucose curves. What do we make of this?

I think this suggests that insulin sensitivity was highest in the control subjects (less insulin required to regulate glucose levels).

If this also correlates with brain insulin sensitivity (not sure if that leap is reasonable or not), then we'd expect less insulin to be required to trigger the same appetite-suppressing effect in the control group.

rezzrovv said...

What of all the objections that high-protein meals create a high insulin response similar to carbs? I have seen a number of studies equating sat. fat with satiation as well.

Don said...

Renaud and Will,

Yes, I think the study cited by Renaud only demonstrated that fats decrease insulin sensitivity. Most likely they decrease sensitivity in the brain equally to the peripheral tissues. This would probably mean that the lower fat group gets more satiation from less insulin.