It’s nearly impossible to read about or learn about any diet and nutrition philosophy without the words “trend” or “fad” popping up. Intermittent fasting is no exception in today’s spectrum of nutrition plans. While fasting has been applied to many religious practices through time, its turn as the latest fitness fad has garnered renewed attention. 

Broken down to its most basic outline, most who practice intermittent fasting simply skip breakfast and stop eating later in the day, creating a window of time between their last meal of one day and their first meal of the next in which their body is fasting. Known as the 16:8 method (16 hours of fasting with an eight-hour window for eating), it’s not so much a diet as it is a pattern of eating that is believed to manipulate our body’s natural hormonal flow for maximized fat burning. Another popular method is to incorporate one or two 24-hour fasts each week as well. 

While it seems like an unnatural or irregular way to go about eating throughout the day (or week), it’s all built from an understanding that our bodies are in fact prepared to go periods of time without nourishment. In fact, it’s a more natural eating pattern than relying on a consistent three meals a day — something that’s really only a product of modern civilization, as our hunter-gatherer ancestors regularly went days without a meal. So thanks to evolution, humans have adapted to function extended period of time without food; while the recent application of this as a health and fitness philosophy has brought much attention to the potential health benefits (or risks) of intermittent fasting today. 

The most popular methods of intermittent fasting in the health and fitness community, according to Healthline, include: 

-The 16/8 method: Also called the Leangains protocol, it involves skipping breakfast and restricting your daily eating period to 8 hours, such as 1–9 p.m. Then you fast for 16 hours in between.

-Eat-Stop-Eat: This involves fasting for 24 hours, once or twice a week, for example by not eating from dinner one day until dinner the next day.

-The 5:2 diet: With this method, you consume only 500–600 calories on two non-consecutive days of the week, but eat normally the other 5 days.

Studies have shown that consistent and disciplined intermittent fasting can increase the growth of human growth hormone (HGH) as much as 500 percent, insulin sensitivity is decreased, natural immune responses improve, and cells initiate cell repair. Studies have also shown intermittent fasting can increases the brain hormone BDNF and may aid the growth of new nerve cells, even potentially protecting against Alzheimer’s disease, it can reduce the markers of inflammation, and it can reduce “bad” LDL cholesterol, blood triglycerides, inflammatory markers, blood sugar, and insulin resistance, which are all risk factors for heart disease. 

While studies have supported all of these possible longterm health benefits of intermittent fasting, researchers at Sao Paolo University uncovered some contrary data points for those intermittent fasters who skip breakfast as part of their routine. Tracking 113 people who had already had heart attacks, they found that 57 percent skipped breakfast at least three times a week and 51 percent ate dinner within two hours of going to sleep. Of their sample group, those who skipped breakfast regularly and ate dinner late were four to five times more likely to either die within a month of having a heart attack or to have a subsequent heart attack. 

So what do they presume to be the key influences on heart attacks within these findings? Funny enough, while some might take the results as an argument to ditch the intermittent fasting approach, they actually may strengthen a case for taking it on as an overall health booster. 

As mentioned, intermittent fasting’s secret weapon for aiding weight loss is that it utilizes the daily cycles of hormone development and usage in ways that maximize the body’s ability to burn fat. In the same fashion, our eating patterns influence the body’s ability to perform other functions optimally. According to a 2018 report by the American Heart Association, consuming a heavy load of calories before bedtime, forcing your body to digest everything while you sleep has a vastly different impact on your overall health than allowing your body to digest and process many of those same calories throughout the day and use them as fuel (coincidentally, when we’re active and more likely to burn those calories off anyway). A late-night meal throws off our body’s natural “clock,” explained lead study author Nour Makarem, a postdoctoral fellow in cardiology at Columbia University Vagelos College of Physicians and Surgeons. The body’s clock being misaligned can triggers risks to a number of health problems such as diabetes, hypertension and heart disease, she said.

"These clocks are regulated by bright-light exposure, but also by behaviors, particularly food signals. The evidence is fairly consistent that eating more, later in the day, seems to be worse metabolically," said Kristen Knutson, an associate professor of neurology and preventative medicine at Northwestern University Feinberg School of Medicine who was not involved with the research, but attended Makarem's talk. These problems arise because "you're not eating at the time that's optimal for your circadian system," she told Live Science.

Simple logic would point to the pattern that’s created by starting the day off without calories, lending itself to a higher likelihood of making up for such a deficit later in the day or into the evening. Body functions slow down as we sleep, including digestion and nutrient absorption, and a full stomach triggers a lower quality of sleep. And consistent poor sleep is yet another top risk for heart complications. A safer practice for intermittent fasters who do skip breakfast is to make lunch the largest meal of the day, rather than dinner. And that final, lighter meal should be at least two hours before bedtime.