A stressful companion

In a broad-reaching review of the effects of over-consumption of food on human health and cognition, the aforereferenced Dr. Mattson Ph.D. from the Department of Neuroscience at Johns Hopkins University School of Medicine, details how the pursuit of higher-calorie food sources through social cooperation, tool use, and other strategies, led directly to the development of human brain mass and intelligence.

Contrastingly, animals placed in an environment where food is available 24 hours a day, experience a shrinkage of the brain compared to their non-domesticated cousins (wildfowl compared to chickens, wolves compared to poodles, etc.)

“Remarkably, measurements of cranial volumes suggest that there has been a ~10% reduction in brain volume in humans during the past 10,000 years which corresponds to the time period after the agricultural revolution and the development of effort-sparing technologies,” Mattson writes, who goes on to note the progression of autism, reductions in BDNF-levels, and more in children, and other health trends that map onto the progression of increased access to food.

One of the principal predictors of survival in our early ancestors was “metabolic switching,” chiefly, the ability to switch from metabolizing glucose as a primary fuel to metabolizing fatty acids.

“When we have food available all the time and we don’t have the need to exercise to get through life, our cells become complacent. They do not maintain their ability to cope with the kinds of stressors that cause disease,” Dr. Mattson told Found my Fitness.

Hormetic stress and fasting

The reduction in energy as associated with 5:2 intermittent fasting or time-restricted eating is a hormetic stressor, meaning that it causes a very mild sort of damage to the body which elicits a much greater therapeutic effect in response.

Sauna use, with its high temperatures, creates a hormetic effect through the release of heat shock proteins that repair muscle tissue. Plants, filled with vitamins and antioxidants, also contain a variety of stress-inducing phytochemicals that cause the body to over-prepare for potential damage.

Fasting works to create hormesis both alone, and synergistically with other hormetic stressors like exercise. Fasted cardiovascular exercise like endurance running recently gained a lot of attention as a potential appetite suppressant or for increasing the expenditure of stored energy. It’s been shown with mass-spectrometry that there is clear switching between glycolytic and ketolytic metabolism, meaning the use of ketones from fat as a principal source of energy —Mattson’s “metabolic switching,” in young men running after a period of fasting.

Intermittent fasting and caloric restriction also have neurological effects. A reduction in calories leads to the production of proteins in the brain called neurotrophic factors that support nerve cell growth. The most studied of these is called BDNF, or brain-derived neurotrophic factor, as it promotes synaptic plasticity, the hallmark of intelligence, as well as stress resistance in brain cells while providing protection against the neuronal dysfunction and degeneration of diseases like Alzheimer’s and Parkinson’s.

It’s said that whatever doesn’t kill you makes you stronger. Mattson’s work shows us a different way of imagining intermittent fasting or time-restricted eating, not as aspects that balance the scales of blood glucose or body fat composition, but rather as instruments within the greater orchestra of synergistic biological fortification that comes from presenting your body with a challenge it must overcome. WaL