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Intermittent Fasting

Interrupted, sporadic. Alternately stopping and starting repeatedly

Intermittent Fasting

Lots of people ask me about Intermittent Fasting. More than 1 million copies of Intermittent Fasting books have been sold in the U.S. and the UK. I have clients who have done it. Most have liked it at first, but then, they have all dropped it.

In this blog, we’ll look at how it’s done, whether it’s easy to keep up, and if it works. (A link to a great medical reference is at the end of this blog. Journal of the American Medical Association – Internal Medicine July 2017.)

How it’s done: 1-Hard core 2- Modified

Hard Core Intermittent or Alternate-day fasting has you for one-day fasting by consuming 25% of your usual intake- which is usually about 500 calories.

You then have a “feast day” in which you can eat as much food as you want, and then some, without restraint. Ick!

Findings from short-term studies indicate that participants lose 3% to 7% of body weight after 2 to 3 months of alternate-day fasting and experience improvements in lipid profiles, blood pressure, and insulin sensitivity.

Easy to maintain?

Some people find that grazing all day then eating one big meal or just skipping one meal gives them more energy. Others get “hangry” if they suddenly get hungry and they can’t even snack. Most people do best on the typical daily calorie-restriction because they like a gradual change of calories and regular meals. In the study with 222 screened participants, the dropout rate was highest in the Intermittent/alternate-day fasting group (13 out of 34 people [38%]). The dropout rate for the typical DAILY Calorie-Restriction was 10 out of 35 people [29%].

Does it work in the long-run?

Like all diets, it can and has worked for some in the short term. That said, in the longest-ran study with the largest number of participants to date, conducted in 2017, the final conclusion was that after one year weight loss by intermittent fasting was comparable to typical diets/daily calorie restriction.

This was done with 100 healthy but obese adults. Weight loss after one year in the alternate-day fasting group (6.0%) was not significantly different from that of the daily calorie restriction group (5.3%). Previous shorter trials of intermittent fasting reported weight loss of 3% to 7% after two to three months of dieting.

The argument FOR Intermittent Fasting is based on the premise that fasting triggers hormonal changes – your insulin levels drop, which allows your cells to release stored fat and use that fat more effectively. Fasting also stimulates a housekeeping process called “autophagy. Without food your cells use that spare time to remove damaged or misfolded proteins. BUT, your body already does this without intermittent fasting or daily dieting. Your body does this within the time you don’t eat (you fast) in between meals and overnight.

Also remember, FASTING IS NOT STARVING. It is not going for days without eating or eating a very low-calorie diet indefinitely. That is dangerous.

There are other fasting diets such as the:

Modified Fasting in which you fast for two-random days (not in a row) and eat normally for 5 days.


Based on my clients experiences, and those of others who’ve chatted about it, and on all my research and reading of various studies in the past few years, I think that intermittent fasting does not result in faster or more weight loss or weight maintenance compared with daily calorie restriction, and it surely does not beat lower calories combined with consistent exercise – especially resistance training.

– Ronnie Loaiza , Certified Personal Trainer

JAMA Intern Med. 2017;177(7):930-938. doi:10.1001/jamainternmed.2017.0936

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