Tuesday, February 9, 2010
Paleo Diet Q & A - 9 February 2010
Today's edition of Paleo Diet Q & A focuses on fasting.
You may have covered this issue already, I have not read that much of your work.
I thought I would point out though that Paleo humans likely went through periods of enforced fasting due to a lack of game or a temporary lack of success in hunting. In fact, there were likely alternating cycles of gorging and fasting. This alternating cycle would change the data on the Paleo diet as modern humans are not likely to be undergoing the fasting phase.
It seems like doing a study using the climate record might help as Paleo man may not have migrated as much as the animals that they hunted.
Have you already covered this?
Just another nutrition student,
A: Dear Bob,
We agree in that hunter-gatherers would probably have been forced to observe periods of intermittent fasting.
In our archive you can find a published issue of our newsletter (Vol. 1; Issue 3) where Dr. Cordain reports that hunter-gatherers usually ate a single meal in the evening and probably breakfast using leftovers from the night before. This makes sense as they spent the day engaged in foraging and hunting activities and returned to their camps in the sunset. Some of the beneficial effects of intermittent fasting are likely due to caloric restriction, a well as known interventions that increase health in animals and humans, and lifespan in animals such as hamsters, mice, rats, fish, insects and worms.
A feast-famine, exercise-rest cycle has been postulated as a healthful lifestyle similar to that of human beings in the paleolithic. Famine and exercise (simultaneously) decrease muscle glycogen and triglycerides stores increasing AMPK and GLUT4 expression. These two proteins are involved in glucose and triglycerides homeostasis, leading to an efficient storage of energy and increased physical performance. If hunting is successful, a replenishment of glycogen and triglycerides is produced. This is followed by a relative period of rest. This efficient storage of energy increases the probabilities of surviving during another famine/exercise period1.
This should be a healthy way to improve health and physical performance from an evolutionary perspective.
1. Chakravarthy, M. V., Booth, F. W. Eating, exercise, and "thrifty" genotypes: connecting the dots toward an evolutionary understanding of modern chronic diseases. J Appl Physiol, 96 (1); 3-10.
I hope this helps.