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Intermittent Fasting: Latest Research

Nov 13, 2019



Vegas, baby.


I recently spent 5 days with some of the most dedicated obesity researchers, clinicians and surgeons on the planet.


Rest assured there are people looking for the answers to weight gain and sustainability and they’re making progress.


Over the next 2 weeks, I’m going to tell you my favorite tidbits—the newest thinking on fat and leptin, weight gain during pregnancy and post bariatric surgery, and the truth about intermittent fasting.


Today’s all about the fast.


Intermittent Fasting


For intermittent fasting the data are clear:

it extends life, decreases weight, and prevents disease . . .


. . . in mice.


In people, things are a little more complicated.


[By the way, this was a theme at the conference—exciting evidence in mice, diluted for people.]


So does intermittent fasting help people?




But not the way you might think.


Weight Loss


There’s no evidence that one loses any more weight with calorie restricted intermittent fasting than with regular old “dieting” (consistent calorie restriction).


Studies done to show this vary in length but the intervention is seldom more than weeks at a time.


So I can’t help but think that over the long haul (which is what we care about around here) there would be significant benefit because . . .


Insulin strikes again


The incredible thing that Intermittent Fasting does for people is to decrease their insulin levels.


This is huge especially for anyone with known pre-diabetes or insulin resistance. And, frankly, equally huge for people who don’t know they have it (which is most of those with the condition).


Remember, insulin is the fat storage hormone and we naturally release some when we eat food, but we release more and therefore have increased levels when we eat processed foods and when we are insulin resistant.


Excess insulin leads to more fat storage.


Who benefits the most?


Anyone with a risk of developing insulin resistance.


That includes:


  • Those with a BMI 25 or above.


  • Peri- and post-menopausal women

(because they experience hormone changes that can predispose them to weight gain and more specifically, abdominal fat (see my review of hormones and weight gain here).


When to eat?


There are many versions of Intermittent Fasting, but the only ones with proven potential for sustainability are the Time Restricted Intermittent Fasting regimes.


With Time Restricted Intermittent Fasting you eat every day in a limited time window. Anywhere from 8-12 hours.


Looks like 8-10 hours gives you more benefit.


And if you want the most benefit, you eat all your meals during daylight hours.


That’s right.


It’s better for metabolism, calorie burn and insulin levels if you eat from 7am to 3pm instead of noon to 8pm.


It has to do with our circadian rhythms.


It turns out you want to eat your meals before you start your “biological night” which is when you start excreting melatonin.


The good news is that 5 out of 7 days gives you the same benefit as all 7.

So when you have special candlelight dinner plans, go for it.


If you want more nitty-gritty details, tune into the Facebook Live today at 12:30pm PST, on my Page: Stephanie Fein MD


All hail Intermittent Fasting!


Intermittent Fasting is a worthwhile health habit that can have long-term body benefits.


But only if it makes sense for you and your lifestyle and preferences.


Just like anything else, this will feel great to some people and not so great to others.

No prob.

It’s just one more tool in the toolbox.