DietsHealth News

Should You Be Worried by the Recent “Intermittent Fasting” Study?



The headlines focussed on how intermittent fasting doubles heart attack risk.

That’s worth worrying about, so let’s check it out.

First, Though, What is “Intermittent Fasting?”


Since IF became a popular trend around eight to ten years ago, “IF” has come to mean just about any eating schedule except the standard American habit of stuffing your pie hole every waking moment.

However, the concept didn’t start out so flexible.


I first learned about IF through the book EAT STOP EAT by Brad Pilon. 

In ESE, Pilon advises skipping meals for 24 straight hours – basically, three meals in a row.

That is, if you skip all three of today’s meals, you return to a normal eating schedule by eating your standard breakfast tomorrow morning.

You can begin by skipping lunch or dinner – then eating again after missing three meals in a row. (That is, if you skip lunch today, you also skip dinner tonight and breakfast tomorrow morning. You break the fast by tomorrow by eating your regular lunch.)

Pilon says to do that one day a week. Not every day or every other day. Just one day a week, if you want to maintain your current physique.


If you need to lose weight, go two days in a week without eating.

But you still eat normally during the other five days.

“Normally” means eating three regular-sized meals a day.

“Regular-sized” means just that, NOT supersized meals to make up for calories skipped.

This seems fairly simple to me, but everybody’s now way overcomplicating it.

Other authors came up with their own schedules, to get you to buy their books.

Also, many people got the idea that if going 24 hours once a week is a healthy thing to do, going without food for even longer periods must be even healthier.


Heck, why eat at all?

We must, obviously, but many people are trying to “IF” by spending as little time eating as possible – EVERY DAY.

They try to get by by consuming just One-Meal-A-Day (OMAD). If they can’t do that, they still compress their daily eating window to under eight hours – which is only sufficient for two meals. 


The Recent Study Really Looks at Health Issues Associated with Various Daily Eating Windows – Not All Forms of IF

It was funded by a science foundation in China, and they worked with both Harvard and Northwestern University. Researchers recently presented the results at a conference of the American Heart Association. Their results surprised the researchers. They fully expected that eating for no more than eight hours a day would prove to lower all-cause mortality, not increase it.

Yet, increased all-cause mortality is what they found. 


Eating only eight hours per day increases the risk of death. Not only the 91% increase in heart disease, as highlighted in the news headlines but 3X the risk of death for subjects who had cancer.

However, their paper has not yet been peer-reviewed. Its findings are concerning, but not yet established, ironclad fact. It was an observational study. That means they kept data on 20,000 people, based on what those people stated – and the results.

An eating window of twelve to sixteen hours was set as normal – the baseline. That’s probably pretty representative of how most people generally eat every day, from breakfast to midnight snacks.


They classified the subjects by whether they ate:

* Under 8 hours per day

* 8 to 10 hours per day

* 10 to 12 hours per day

* 12 to 16 hours per day (considered the baseline)

* Over 16 hours per day

Some of the subjects were healthy. Others already had heart disease. Others had cancer.

The researchers did adjust the data for many various factors, including levels of exercise, BMI and “diet quality.”


The Results are Striking

People who had heart disease demonstrated increased risk when eating less than twelve hours a day. 

But everyone who ate less than the default range of 12 to 16 hours per day – or more than 16 hours per day – had an increased risk of heart attack.

For people with cancer, eating less than eight hours per day actually TRIPLED their risk of dying. 

Even healthy people increased their risk of death if they ate outside the standard 12 to 16 hour window.


One Good Criticism

The subjects were not trying to fast intermittently. The data comes from surveys done from 2003 to 2018. Back in 2003, nobody even knew what IF was. Therefore, their reasons for eating for under eight hours a day may itself have had an effect on their health, such as a highly stressful job.


Other Possibilities

People now practicing IF have been told it’s NOT what they eat or how much or when that matters – just for how long.

That’s probably not a complete picture.

People eating OMAD or under 8 hours per day are often on the keto diet. We’ve known for over ten years the keto diet significantly increases all-cause mortality. Although the researchers say they controlled for diet quality, they didn’t go into detail. 

Even if they’re not on a strict keto diet, people feeling worried about consuming low amounts of protein and fat are more likely to eat energy-and-protein-and-therefore-calorie-dense foods than lighter plant foods. 


It’s hard to eat 2,500 – 3,000 calories every day within an eight-hour window.

Therefore, trying to do so encourages people to consume lots of oil, sugar and other processed foods – just to take in enough calories and protein.

Therefore, they’re consuming more saturated fat and less fiber and antioxidants. 

And doing it in a small, tight time frame that encourages eating big, heavy meals.


It could well be that cramming your gut every day with large amounts of rich junk spikes your insulin and blood sugar levels so high, that alone is more damaging than the three more moderate spikes you experience by eating three average-sized meals in a day.

To keep their eating within eight hours, many people skip breakfast. Yet, as we know from many other studies, not eating breakfast is itself a health risk.


Suggestions in Light of the Study

1. Don’t put your body under the constant stress of either starvation or stuffed to the gills.

Unless it’s Thanksgiving, eat only moderately sized meals. A heavy meal can itself trigger the onset of a heart attack.

Don’t follow the modern American habit of eating nonstop snacks, but don’t intentionally starve yourself for many hours past the point of hunger, either.


2. Quality must still matter.

Avoid junk, saturated fat, processed sugars and so on.

Consume more plants: whole grains, beans, fruits, vegetables and nuts. Lightly processed plant foods contain lots of fiber and antioxidants. That will make you feel fuller while you take in fewer calories.

Also – plant foods moderate spikes in blood sugar and insulin, which is the whole point of intermittent fasting.


3. Eat on a sensible schedule based on your work and your family.

Twelve to sixteen hours per day should give most people plenty of time for breakfast, lunch and dinner with their loved ones.


4. As much as possible, try to avoid eating at least four hours before bedtime.

5. If you’re getting good results by fasting one or two days a week, don’t let this study bother you – as long as you use common sense and pay attention to what your body is telling you.


Also, don’t think IF is a magic, anti-aging health wand. You still want to eat three healthy meals five to six days a week, get consistent moderate exercise and plenty of sleep.