Short- and Long-Term Effects

Sometimes the short-term (acute) effects of some stimulus are different from the long-term (chronic) effects. One well-known example of this is the effect of free fatty acids on insulin release. In the short term, they stimulate insulin release, but in the long term they inhibit it.

Now it has been found that the effects of prednisone depend on how often you take it.  Daily prednisone promotes obesity, but weekly prednisone promotes increased lean body mass. The researchers also found that the weekly prednisone caused an increase in adiponectin, a hormone that protects against insulin resistance.

And another study shows that ceramide, a lipid, reduces stress in cells in the short term, but in long-term metabolic diseases like diabetes, the ceramide may kill the cells. 

What this means is that when you read about some study, notice how long the study lasted. If a new drug reduces blood glucose levels after a week or a month, will that effect last 6 months or a year or even longer? The same holds for some nondrug treatment.

The body is constantly adapting to its environment, including drugs as well as diet and exercise patterns and stress. Research papers don't always control for that, and such control would sometimes be difficult. For instance, researchers can't really measure how much stress the subjects have had during the course of the study, or if the subjects have started getting groceries from a different place, maybe a farmers market instead of a grocery store or vice versa as the seasons change.

But it's good to be aware of the possible effects of time.

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