The jury may still be out on the specifics of the diets of our paleolithic ancestors. But one thing is certain. Early Homo sapiens sapiens didn't have the luxury of kitchens with well-stocked refrigerators!
Our ancestors definitely had to expend energy to feed themselves and there would have been many a lean time through the last 200,000 years. But despite the lean times, the effort required to find food and plenty of inhospitable environments, our species has survived and flourished. Therein lies a clue. Perhaps Nature factored in calorie restriction and exercise into our basic blueprint? And perhaps in doing so, She turned a potential negative to a positive? It's more than interesting that, malnutrition aside, those of our species that don't have access to 'food on tap', generally live longer, healthier and happier lives. And they certainly don't suffer the long list of maladies common to those of the species with the well-stocked kitchens.
There have been over 2,000 papers in the last ten years looking at the effects of calorie restriction (CR) on everything from single-celled organisms to primates. The general conclusion: longer, healthier lifespans, enhanced performance and optimised weight. It's known that CR affects key pathways in the body that regulate metabolism, cell growth and cell proliferation. For instance, CR is able to deactivate the nutrient-sensing mTOR pathway, which slows down aging and prevents age-related diseases such as type II diabetes; it can also regulate insulin levels and insulin-like growth factors necessary for blood sugar control and cell growth, to name but two. When these and other metabolic pathways become disturbed, the result is, unfortunately, obesity, shorter lifespans and increased incidence of chronic disease. Coming back to our basic blueprint as Homo sapiens sapiens, maintaining health is all about maintaining metabolic flexibility. By that we mean the ability to provide sufficient energy for our bodies to perform, but not so much that we need to start storing the excess as fat and creating disease. The excess being the curse, rather than the luxury, of our modern world — the 'Well-Stocked Kitchen Syndrome'.
Our bodies are perfectly adapted to periods of starvation and have developed a number of systems for maintaining sufficient energy for the brain, immune system and performance. In his May 2012 paper, Mikhail Blagosklonny explains that to feed the brain during non-malnutrition starvation (i.e. intermittent fasting), the liver produces glucose from protein building blocks, amino acids, (gluconeogenesis) and ketones from fatty acids (ketogenesis). Fat cells (adipocytes) need to release the fatty acids to fuel the ketogenesis and secretion of insulin by the pancreas is decreased to enable the liver to carry out these specific functions. The key noticeable metabolic alterations arising from CR are gluconeogenesis, ketogenesis, low insulin levels and increased lipolysis.
In short, our body has been made to split its own proteins and fats to make energy, i.e. keeping metabolically flexible, rather than needing to consume huge amounts of calories for energy. Remember the old adage; 'use it before you lose it'? Well, it's the over consumption of calories (particularly empty carbohydrate calories) that disables our metabolic flexibility in the first place and hinders our fat burning potential.
The effects of both CR and exercise are amply demonstrated by Fontana et al in a study conducted in 2007, looking at 84 people divided into 3 groups. The first group had been carrying out CR for nearly 7 years; the second were endurance runners (EX) and the third, the control group of sedentary individuals eating a conventional Western diet (WD). They found that the CR and EX volunteers were significantly leaner than the sedentary WD control group. Also that the CR and EX groups had much higher insulin sensitivity, very low inflammation and higher levels of adiponectin — a protein found in fat cells that allows you to burn fat. A more recent 2012 study from Fontana's group found that heart rate variability in CR individuals was comparable with published norms for healthy individuals 20 years younger. Happy days, there's our blueprint in action again!
So by mimicking our predecessors and eating less frequently (no snacking between meals), including 3-4 times a month of intermittent fasting (starvation) of between 18 – 20 hours and ensuring that exercise is taken before eating within the fasting period, we can regain and prime our metabolic flexibility. The results of which include extending life, delaying disease, enhancing performance (mental, emotional and physical) and optimising weight. And it's really not difficult if you're optimising your nutrition with good quality protein, healthy fats and lots of antioxidants from vegetables and fruits.
Updated: 20 Jun 2012
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