We’ve heard for years that it’s bad to skip meals. Some health experts advise us to eat five or six small meals daily, which means you are never more than a few hours away from eating. But much research suggests that as a regular routine, skipping meals could be healthier than eating throughout the day, every day.
The reason is that we once ate more like lions do. They kill and eat prey a few times a week or less often. Early human beings didn’t snack all day, that’s for sure.
Our overall genetic makeup probably derives from the Late-Paleolithic era, when we had to expend lots of energy to acquire our food and cycled between feast and famine. Our metabolisms may expect us to live off berries for a stretch until we nail some antelope-meat or, even better, some delicious fish or shellfish. We also typically ate during daylight hours, not round the clock.
Wait—no ice cream at bedtime? Why give up the luxury of ready food all day long? Because wild animals and modern hunter-gatherers rarely suffer from obesity, diabetes, and heart disease, the epidemics of overfed civilization.
The term of the day is “intermittent fasting.” But I like to think of it as “eating with big breaks.”
How to do it
There are several approaches. In the 5:2 approach, you eat whatever you want for five days and only 500 calories — about one light meal—on two days a week. Some people eat 500 calories every other day and normally on the other days. Some eat only within a tight window of hours each day, which means skipping meals.
If you had to fast for a religious holiday, you might have experienced it as tough. But the body adjusts over time, so it will be easier if you keep to a routine. If you like low-carb diets (which are a good idea for many reasons), you are a good candidate for this approach, since it too forces the body to burn fat for energy. And people who prioritize protein and fat over carbs tend to have more stable insulin and fewer hunger “spikes.”
Krista Varady, a professor of nutrition at the University of Illinois at Chicago, says that restricting the hours in the day you eat can be a simple approach for weight-loss: There’s no calorie-counting and you can eat what you want. She and her colleagues tested two eating plans on a group of volunteers, largely women in their forties: eating only between 3 p.m. and 7 p.m. or eating only from 1 p.m. to 7 p.m. In both cases you could eat an early dinner with family.
Over eight weeks, her diet volunteers lost about 3% of their body weight, on average (Cienfuegos et al., 2020).
Mark Mattson, a neuroscientist at the National Institute on Aging in Maryland, offers this strategy to lose weight: stop eating by 8 p.m., skip breakfast the next morning and then eat again at noon the next day.” (You can have sugar-free black coffee or tea before lunch). You might not see an effect for four weeks (Brody, 2020).
When obese people have been studied on alternate-day fasting regimes, they lost weight even if they ate a high-fat diet on their eating days and up to 500 calories on their fasting day. In these studies, 10 percent to 20 percent of people usually drop out but after several weeks, the others adjust, and are less hungry on their fast days. They also don’t gorge on their eating days (Klempel et al., 2012).
Why you might try it
Intermittent fasting got some bad press after a recent study that found that people lost muscle mass. In that research, a group that ate only during eight hours a day lost weight, and the controls didn't (Lowe et al., 2020). It's normal to lose muscle when you lose weight, but there is a solution: do weight-bearing exercise and favor protein. (We suggest seafood, for the reasons summarized here.)
The benefits go beyond weight loss. Eating with breaks improves insulin resistance, blood fat abnormalities, high blood pressure and inflammation, even independently of weight loss (Brody, 2020). When cells are forced to burn fat, the result is better blood sugar regulation. Eating with breaks can cut symptoms of asthma and arthritis (Johnson et al., 2006), possibly because fasting cuts inflammation. Patients with multiple sclerosis saw their symptoms improve in two months (Fitzgerald et al., 2015).
Animal studies suggest that it can ease symptoms of lupus and both type 1 and type 2 diabetes (Mattson et al., 2017). A 2015 mouse study found that just two to five days of fasting each month reduced biomarkers for diabetes, cancer and heart disease (Brandhorst et al., 2015).
Fasting lowers insulin and another hormone called insulin-like growth factor, or IGF-1, pushing the body to stop pushing for new cell growth, which in effect slows aging. Animal studies show a positive effect on the brain, enhancing several forms of memory (Cabo et al., 2020).
Blogger James Clear reports that he eats one meal at 1 p.m. and another at 8 p.m. each day, and doesn’t eat again for the next 16 hours. After his first year on this regime, he increased his muscle mass and decreased his body fat even though he cut his training time at the gym from 7.5 hours to 2.5.
The Web abounds in similar anecdotal reports; you might browse this active Reddit board, this site by a personal trainer, and this one from a diet coach, and see if you’re inspired to try. If you seek more official forms of research, check the sources at the bottom of this article.
One way to get started: You might try regarding any sense of hunger as a form of exercise; that is, short-term wear and tear on the body that makes it stronger. You might be hungry and cranky, but only at first. Over time, people adjust, especially if they cut back on carbohydrates as well. Give it at least a month to decide.