• Atara Weisberger

Intermittent Fasting - Fad or Fact?



Is there a difference between reducing calories

evenly throughout the week (daily calorie restriction)

and fasting (extended duration calorie reduction)

in terms of fat metabolism?

University of Florida health researchers recently published a

study in the journal, Obesity, that emerging findings in

scientific literature show intermittent fasting can be a reliable

means of weight loss and may optimize physiological

functioning, enhance performance and slow the aging

and disease process.

To understand why, researchers said, one must look to how

the body essentially flips a “metabolic switch” during fasting.

This means the body moves from burning glucose, or sugar,

for energy to fatty acids and their byproduct, ketones.

During fasting, the body converts fat into fatty acids,

which can be absorbed by the blood.

Stephen Anton, Ph.D., the division chief of clinical

research for the UF College of Medicine’s department

of aging and geriatric research and the paper’s lead

author, said research indicates ketones are the preferred

fuel for the brain and body during periods of fasting and

extended exercise.

Ketones, he said, are a cleaner source of energy than

glucose, protein or carbohydrates, the body’s other

sources of energy. Typically, he said, after eight to 12

hours of fasting, the levels of ketones in the blood

significantly increase.

Anton’s paper looked at two popular forms of intermittent

fasting. The first is time-restricted feeding, when the

dieter eats during discrete windows during the day.

For example, they might fast 16-18 hours a day,

eating during the other six to eight hours.

In that window, the dieter isn’t restricted to what they eat.

The second approach is called alternate-day fasting.

In the more common model of this fasting regimen,

people limit their meals on one day, usually to 500 calories.

On the next day, they can eat anything at all.

A second version of this fasting method is to eat

nothing at all on one day while feasting the next.

In a review of scientific literature, Anton and his

colleagues found that people lost significant body

fat in 10 of 10 clinical trials involving alternate-day fasts.

Three of four time-restricted feeding studies

demonstrated significant fat loss.

Anton said research in rodents and other nonhuman

species points to the possibility that food restriction,

and the turning of that metabolic switch, can lengthen

lifespan, improve metabolic health, cognitive and

physical performance, lower inflammation and lead

to superior cardiovascular health.

More research needs to be done to see if there are

additional metabolic benefits that are unique to

intermittent fasting, aside from fat mobilization.

There are downsides to fasting and it is not appropriate

for everyone. Please discuss fasting with your doctor.


The concerns with intermittent fasting:

Reported risks with interrmittent fasting include nausea,

dizziness, abnormal liver function, decreased bone density,

thiamine deficiency, and poor athletic performance

on fast days.

Because food quantity and quality are unrestricted on feeding days/hours with intermittent fasting, poor food choices can

erase the benefits of fasting and harm health.


What about standard dieting (daily caloric restriction)?

Standard daily caloric restriction has been proven time

and again to also increase fat mobilization, particularly in combination with exercise.

Standard dieting encourages consumption of

nutrient dense, energy efficient foods.


If you have fat to lose, how do you proceed?

Ask yourself the following:

What can I stick with long term?

What works best for my life and my body?

What approach will facilitate making the best overall

food choices for maximal nutrition and wellbeing?

The ultimate objective is life long health and wellness

so choose lifestyle habits that you can and will maintain

and that help you reach your goals!

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