Mark Mattson, a neuroscientist with Johns Hopkins Medicine, is the senior author of a review of intermittent fasting that appeared in the New England Journal of Medicine. Mattson has fasted for 20 years himself and says the science now backs up intermittent fasting to a point where it can be considered a legitimate approach, with a healthy diet and exercise, to improve and maintain health.
Mattson explains that when people are fasting, they burn through the glucose stored in the liver. It takes 10 to 12 hours to use the fat for energy. The fact that most people eat three meals a day means they don’t go through the energy stored in the liver and switch to fat burning.
The new paper provides a summary of the scientific evidence of various studies that show intermittent fasting can stabilize blood sugar levels, suppress inflammation and increase resistance to stress. It can also improve the resting heart rate as well as blood pressure, cholesterol levels and brain health.
Ways to incorporate intermittent fasting into daily life
With intermittent fasting, you do not cut out any food groups or count calories. You just modulate when you eat.
In the paper, Mattson lays out various ways to incorporate fasting into your daily life. For example, people could limit themselves to a feeding period of 10 hours for five days a week for a month and then bring it down to eight and then six hours in subsequent months. The goal would be to reach a six-hour feeding period for seven days a week.
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What to expect
Mattson says it takes a while to get into your new routine and your body may be a little uncomfortable as it adjusts. When you switch to intermittent fasting, you may experience some irritability, fatigue, hunger and be less able to concentrate during the periods when you’re not eating. However, these initial side effects usually disappear within a few weeks.
The fact that a diet of three meals a day with snacks is ingrained in our culture makes adopting intermittent fasting harder. The abundance of food and extensive marketing in developed countries is another hurdle to overcome.
It’s also important not to expect immediate results. It can take a few weeks before you start losing weight or seeing any health improvements. You also need to keep in mind that you don’t have free license to eat what you please when you’re not fasting.
Fasting isn’t recommended for some people – people with low body weight, children and the elderly.
More research is being done
Mattson says more research needs to be done into the health benefits of fasting. There’s a strong argument that it could improve cancer treatment. Cancer cells feed on glucose, not fat. If cancer cells are hit with chemo or radiation while a person is fasting, they are killed more easily. Multiple trials are on the go to see if fasting could help in the treatment of cancer.
Clinical trials have shown that intermittent fasting has benefits for many health conditions, such as diabetes mellitus, obesity, cancers, neurological disorders and cardiovascular disease.
Animal models show that intermittent fasting improves health throughout the life span but as clinical trials have not yet been done over lengthy periods, it remains to be seen whether the benefits of increased life span in animals will also be seen in humans.