In the 1930s, research demonstrated that rats would live twice as long if their calorie intake was cut in half. In human terms, the calorie-deprived rats reached an age of 150 years. They were also less disease prone throughout their lives.
But those are rats. What about humans?
And does a life with 50% fewer calories just seem longer?
In all seriousness, until recently we didn’t have good data on whether this would even be safe for people. Would there be issues with dangerous bone loss or muscle wasting? After all, eating disorders such as anorexia do not result in better health.
About a year ago, researchers at University of Wisconsin reported their work with rhesus monkeys, a species that shares 93% of its DNA with humans. As part of the experiment, they started one 16 year old rhesus monkey on a 30% calorie restricted diet. 16 years in a rhesus monkey is equivalent to middle age in humans. That monkey is now 43 years old and healthy – a longevity record for the species – and equivalent to 150 years for humans. Other calorie-restricted monkeys are following suit.
A human intervention trial with intermittent fasting for 3 months has also shown promising results. In this study, subjects had calorie intake reduced by 50% for 1 day (down to 1100 calories) and then by 70% (down to 700 calories) for the next 4 days. During the fasting periods, they ate only plant-based foods. For the rest of each month, the subjects ate whatever they wanted. The researchers found that participants’ weight, cholesterol profiles and blood sugar levels improved not only during the 3 months of the intervention but for at least 3 months after the trial. There were no counterproductive side effects of this intermittent fasting approach, and the greatest benefits were seen in individuals who were obese or otherwise unhealthy to start.
Other studies have shown better-preserved learning and memory function in animals subjected to intermittent calorie restriction, but there is no equivalent data in humans to date. Trials are ongoing.
Although the medical community is not ready to start recommending long-term marked calorie restriction or intermittent fasting just yet, this data is intriguing. It may be that intermittent fasting could become an additional tool for battling cardiometabolic disease and that aging is more malleable than we think.
What is also thought-provoking is that intermittent fasting is integral to many faiths. Fasting can last for just a few hours or even a few weeks, usually with practitioners eating at night. For example, Mormons skip two meals on the first Sabbath of every month. Other religions and philosophies that practice intermittent fasting include: Buddhism, Christianity, Islam, Judaism, Taoism, Jainism, and Hinduism. Although fasting in the religious context is more about purification of the soul and serves to bring communities of faith together, our ancient ancestors may have been well ahead of modern scientists and recognized the potential health benefits as well.
Whether intermittent fasting emerges as a therapeutic option or not, there is no debate that eating highly nutritious plant-based foods is an integral component of health maintenance and disease care. And highly nutritious plant-based foods are naturally lower in calories. For example, two servings of Step One Foods total only 320 calories, on average.