Think about this question: would you be willing to put up with hunger pangs and irritability for a couple of weeks if you knew from then on you could live a longer, healthier, and smarter life? Sound unlikely? And yet, the latest scientific evidence suggests that a dietary pattern called intermittent fasting has a big payoff just for putting up with a brief but slightly uncomfortable adjustment period.
Intermittent fasting (IF) is exactly what the term implies: intersperse your normal eating with short periods of eating nothing. While there are many ways of going about this, the two most prevalent methods are:
- Confine daily eating to a 6-8 hour window, and don’t eat outside of those hours, or
- The 5:2 method in which you eat normally five days of the week, but on two days eat only one moderate-sized meal (500-600 calories).
Many people who choose to practice IF jump in rather abruptly, in which case they may experience hunger pangs and feelings of irritability for 2-4 weeks until their bodies get used to what’s happening. However, there are ways to phase into an IF program (with your doctor’s knowledge and consent) and avoid a discouraging transition. But the question is, why even take on intermittent fasting to begin with?
Benefits of intermittent fasting
The last time I wrote about intermittent fasting I presented the work of Dr. Valter Longo (USC Longevity Institute). This time, I will focus on the work of Mark Mattson PhD, a neuroscientist at the National Institute on aging. For years, he has been studying the benefits of IF at the cellular and molecular levels. In late December 2019, he and associate Rafael de Cabo PhD published an article in the prestigious New England Journal of Medicine titled “The Effects of Intermittent Fasting on Health, Aging and Disease.”i
A major concept behind IF is what Dr. Mattson calls metabolic switching that appears to be an evolutionary adaptation to periods of food scarcity. Metabolism is a pretty broad term, but in this context think of it as the way cells break down nutrient resources and convert them to energy. Metabolic switching happens “…when cells use up their stores of rapidly accessible, sugar-based fuel, and begin converting fat into energy in a slower metabolic process.”ii
There is a saying that what doesn’t kill you makes you stronger. While we tend to say this in a tongue-in-cheek way when we’re under stress, it’s actually true if the stressor is essentially good for us. For example, if you do aerobic exercise or weight training, you are “stressing” your body for a good reason—and your body responds favorably with better cardiovascular function or weight management or other benefits. In the same manner, metabolic switching triggers a number of processes that promote health and longevity, and as humans we can trigger metabolic switching by voluntarily “stressing” our cells in a good way, which has beneficial results.
It’s worth highlighting some key benefits from the recent article as well as Mattson’s earlier research:
- Improved blood sugar regulation
- Better resistance to stress
- Reduced inflammation in the body
- Lowered blood pressure
- Lowered cholesterol
- Slower resting heart rate
In addition, “Fasting has been shown to improve biomarkers of disease, reduce oxidative stress and preserve learning and memory functioning…”iii
Fasting may also have an indirect effect on prostate cancer. First of all, when consistent, a practice of intermittent fasting can reduce the vulnerability toward obesity and diabetes, both of which are linked with developing cancer. Secondly, fasting helps cell membranes become more sensitive to insulin, helping them metabolize is more efficiently and remove glucose (sugar) from the blood. Better regulation of blood sugar makes it harder for cancer cells to thrive.
However, a 2010 lab animal study on fasting and prostate cancer by Thomas, et al.iv cautions that mice who fasted two days per week but were allowed to eat freely the other five days tended to overeat on the nonfasting days, thus apparently canceling out any positive effects of IF. In other words, practicing IF two days per week is not a license to go crazy with high-calorie goodies the other five days. This “breaking the fast” has been a concern ever since IF became something of a fad among health-conscious practitioners. “Another concern is that promoters of intermittent fasting will, perhaps unintentionally, encourage extreme behaviour, such as bingeing.”v
That said, Dr. Mattson himself embraces IF in his personal life, and sees it as part of a healthy lifestyle. For yourself, before embarking on IF or any other dietary change, be sure to discuss the merits and possible negative effects on your health with your doctor.
ide Cabo R, Mattson MP. Effects of Intermittent Fasting on Health, Aging, and Disease. N Engl J Med. 2019 Dec 26;381(26):2541-2551.
ii“Intermittent fasting: live ‘fast,’ live longer?” WorldPharmaNews, Dec. 27, 2019. http://www.worldpharmanews.com/research/5070-intermittent-fasting-live-fast-live-longer
iiiCollier, R. Intermittent fasting: the science of going without.” CMAJ. 2013 Jun 11; 185(9): E363–E364.
ivThomas JA, Antonelli JZ, Lloyd JC, Masko EM et al. Effect of intermittent fasting on prostate cancer tumor growth in a mouse model. Prostate Cancer Prostatic Dis. 2010 Dec;13(4):350-5.