American culture is unique in the way it emphasizes overconsumption. If you travel anywhere outside of the states, you will likely be shocked by the differences in portion size. Americans are taught from a young age that the more food you can get at a low price, the better. Additionally, healthier alternatives are locked behind paywalls, guaranteeing poorer health outcomes for members of lower socioeconomic brackets. It should be no surprise that nearly 50% of adults in the United States qualify as obese (CDC, 2021). Unfortunately, obesity has been linked to several aging processes discussed here, including inflammation, DNA damage, and dysfunction of cellular signaling pathways (Salvestrini et al., 2019).
Thousands and thousands of researchers have devoted their lives to investigating ways to stave off the aging process. Through their work they have made significant progress toward this end. They have found that while overconsumption leads to complications and advanced aging, underconsumption seems to have the opposite effect. Fasting has shown consistently positive results in improving overall health and slowing the metabolic changes that come with aging (Longo et al., 2021). In this article we are going to examine the metabolic effects of intermittent fasting on a microscopic level.
Intermittent fasting is a process by which an individual fasts for a period of time between 12-48 hours for 1-7 days of the week. A common example of this type of fasting schedule is to restrict eating between 12pm and 8pm (skipping breakfast and eliminating post dinner snacks). So let’s look at some ways in which this affects the body:
- Insulin Levels: Insulin is a hormone in the body that signals cells to take in glucose (simple sugars) to break it down for energy. When we eat, insulin is secreted to allow us to uptake the sugars in our food. However, when we spend extended times fasting, our body will use up all of the glucose in our system and resort to using fat for energy. This is incredibly important as excess fat leads to chronic inflammation, and excess sugar leads to decreased sensitivity to insulin (i.e. it takes higher levels of insulin to bring sugar into cells from the blood) and eventually Type II diabetes. By fasting, we work to increase insulin sensitivity and reduce fat stores (Tello, 2019; Wallis, 2020; Johns Hopkins University, 2021)
- Less Mitochondrial Activity: By forcing your body to rely on fat as its main energy source, you vastly reduce the number of metabolic reactions that are conducted within the mitochondria. If you think back to what we learned in here, you will remember that high levels mitochondrial activity lead to the release of more free radicals, damage of mitochondrial DNA, and increase underlying levels of inflammation within the body. This inflammation has been strongly linked to the development of cardiovascular insults such as atherosclerosis and chronically high blood pressure (Dong et al., 2020; Malinowski et al., 2019; Wegman et al., 2015)
- The Warburg Effect: The Warburg Effect is a well documented phenomenon seen in the metabolic activity of cancer cells. Essentially, most tumor cells rely primarily on glucose-based metabolism to grow and reproduce. By shifting your body’s metabolic processes toward fat-based metabolism via intermittent fasting, you can drastically blunt the ability of cancer cells to thrive. This is not a cure for cancer by any means, but it can serve as a protective factor (Antunes et al., 2018; Bianchi et al., 2015; Weng et al., 2020).
As you can see, controlled fasting has the potential to alter one’s metabolism in a very positive way. That being said, I believe it is incredibly important to acknowledge the potential negative impacts on mental health. For any individual who is or has suffered from any type of eating disorder, restrictive diets can be incredibly triggering and unhelpful. Healthwise, YOU ARE ALWAYS better off avoiding relapse of an eating disorder than engaging in a fasting technique! Diets like this are not for everyone and just because this diet may not work for your lifestyle does not mean you cannot live a healthy, long life!