Healthy Food & Healthy Living by Dr. Ayala

Does intermittent fasting change your microbiome?

Most nutrition research is about what you eat. People, however, are complex biochemically and psychologically, we aren’t a simple engine using fuel, so what we eat is just part of the equation. We’re learning that the when and the how of food make a difference.  

Intermittent fasting is gaining popularity as a wellness regimen. People seeking weight loss, better sugar metabolism and heart health opt to limit their eating window to much less than their waking hours – 6 hours of eating and 18 with no food is one common regimen. 

There’s some evidence that it works.

Most diets work because they lead to a reduction in caloric intake – any plan that achieves a caloric deficit leads to weight loss. Is the intermittent fast just a trick to eat less, a way to reduce caloric intake without counting calories, or is there also a metabolic bonus that changes how our body treats the energy we consume according to some mysterious inner clock? 

Lessons from ritual fasting 

There are hints from research that intermittent fasting is actually more than just a trick for consuming less. The weight loss seen in some, but not other, studies is in excess of what you’d expect from just the caloric deficit. 

If people indeed lose more weight than expected through intermittent fasting what could explain that?

A proposed mechanism involves one of the most intriguing and promising subjects in current human metabolism: the microbiome. Our gut microbiome consists of trillions of microbial cells, outnumbering our own human cells nine to one. There’s growing evidence that specific gut bacteria regulate fat metabolism and affect obesity. Does intermittent fasting change the microbiome? 

Microbial allies

A new study in the American Journal of Clinical Nutrition utilizes a type of intermittent fasting practiced by a vast number of people around the world: the fast of Ramadan. Ramadan fasting is from sunrise to sunset, around 16 hours a day, for an entire month. Unlike the silicon valley intermittent fasters, who might be health seekers with multiple other confounding health related behaviors, religious fasters are a widely varied group. The cohort was recruited in China, and included healthy non-obese men.

In this group, eating only between sunset and sunrise resulted in weight loss. It also resulted in beneficial impacts on the gut microbial population. Fasting increased the diversity of gut microbes, and increases in populations of the butyric acid-producing Lachnospiraceae, which are microbes linked with health benefits.

What happens after Ramadan ends? The gut microbial population gradually returned to its baseline.

The authors propose that the beneficial microbes, and the molecules they excrete, may be responsible for the physiologic advantages of time-limited eating. 

This study’s results, if confirmed by other research, may offer yet another method to improve the population of the tiny helpers residing in our gut. Intermittent fasting research is still in its infancy though.

We know a lot more about how dietary and lifestyle habits, medications and the environment affect our microbiome, and the key dietary components to keep in mind when thinking about the health of your microbiome are whole plant foods (fruits, vegetables, grains, legumes, nuts), lots of fiber (whole plant foods take care of that), and reduction of refined and highly processed foods.

To be proactive in cultivating good bacteria choose the foods that we already know are good for us human hosts.

Dr. Ayala

Two proven ways to halt aging and disease

A milestone birthday, a forehead wrinkle and a temporary bout of morning stiffness lead many to seek all kinds of creams, supplements and regimens in search of lasting youth. Less hopeful individuals sigh and accept these as a sign of inevitable decline.

There’s no sound scientific support for those youth-in-a-bottle miracles.

There is, however, plenty of evidence that the decline and disease associated with age can be dramatically altered.

Several metabolic risk factors are known to lead to type 2 diabetes, heart disease and cognitive decline: abdominal obesity, high blood pressure, abnormal lipid profile, insulin resistance and high blood sugar. The clustering of three of these metabolic risk factors (abdominal obesity measured by waist circumference, elevated blood glucose at fasting, high blood pressure, unfavorable cholesterol and high triglycerides) is defined as the metabolic syndrome. And these risk factors, when present in people’s thirties, forties and fifties, can lead to deteriorating health later in life.

Age-associated diseases are lifestyle dependent

These risk factors, however, are highly amenable to lifestyle choices. Diet and exercise are super important. Many studies show that adhering to a healthy diet lowers the risk of the metabolic risk factors of disease mentioned above. Many studies prove that exercising regularly, and avoiding a sedentary lifestyle help prevent this myriad of metabolic risks. 

And now, a new study in the Journal of the American Heart Association looks at the effect of each modality, and, more importantly, at the protection they offer when combined.

The researchers followed almost 2400 people aged 18 and up from the Framingham Study, looking at their adherence to diet and exercise recommendations. Physical activity was assessed by wearing an accelerometer for eight representative days, to assess moderate and vigorous physical activity. Diet was assessed by questionnaires, and compared to the recommended Dietary Guidelines for Americans.

Among the participants, only 28 percent followed both diet and exercise, while almost half followed just one of them, diet or exercise.

When the participants achieved the desired minimum of 150 minutes of moderate to vigorous activity per week, the risk of metabolic syndrome was reduced by half. 

When the participants adhered to the dietary guidelines, the risk of metabolic syndrome was reduced by a third.

Metabolic syndrome risk was 65 percent lower in people who adhered to both fitness and diet recommendations!

And for all these lifestyle choices, there's a dose response link: the more people exercise and the better they eat, the better the outcome.

Bear in mind that this study doesn’t define adherence to a healthy lifestyle too ambitiously. Two and a half hours of moderate to vigorous activity per week and eating according to the American Dietary Guidelines – which are no more than a sensible dietary pattern that emphasizes nutritious choices, while allowing moderate amounts of pretty much everything else – isn’t a tall order.

While according to this study you don’t need to be a health fanatic to reduce your risk of disease, we know that sadly, very few American’s eat well and exercise, and metabolic health is pretty rare in the US. According to a recent study of 9000 Americans whose metabolic health was assessed by measuring five parameters (blood pressure, waist circumference, fasting blood glucose, triglycerides and cholesterol) only 1 in 8 people had optimal levels of all five.

Joyful prevention 

We’ve been focusing on lowering our disease risk at considerable sacrifice this year – preventing Covid-19 spread kept us to ourselves and six feet apart for more than a year.

Now that we’ve been practicing preventive measures to improve our health, here’s some good news: The measures needed for keeping our arteries and brain supple don’t involve the type of deprivation we engage in to prevent Covid-19 spread. They don’t involve isolation; quite the contrary! Most exercise activities can be social, and usually keep you social with the sort of people that will keep you young. And eating healthfully can be super delicious – look at the Mediterranean Diet with all its mouthwatering fresh delights, look at the colorful bounty of the markets.

Dr. Ayala