Practicing Intermittent Fasting Versus Calorie Restriction

Intermittent fasting and calorie restriction are two ways of reducing your calorie intake to obtain health benefits. Intermittant fasting might be accomplished by eating every other day, for example, while calorie restriction means eating every day, but eating less. In both cases, you have to make sure your intake of micronutrients is optimal, and your physician agrees, as for any sane dietary choice. On the scientific side:

  • Both calorie restriction and intermittent fasting produce significant health and longevity benefits in shorter-lived mammals such as mice, and at least significant health benefits in primates, including humans.

  • Far more research has been accomplished for calorie restriction, and uncertainty remains as to whether intermittent fasting is as good, definitely increases longevity, has a preferred method of practice, or whether it could even be harmful to long-term health if done incorrectly.

  • It seems plausible that calorie restriction and intermittent fasting produce their benefits in similar but different ways, based on research in lower animals, but I know of no research confirming this in mammals.

From the point of view of actively practicing either intermittent fasting or calorie restriction, intermittent fasting is much easier for anyone whose eating habits interact with those of other people, or who is already fairly set in his ways with good dietary habits. You just don't eat some days - very simple, and few other changes to the routines of life are needed.

Starting to practice calorie restriction, on the other hand, requires greater effort and more thought in terms of changing your diet. It's not hard, especially given the good resources available to walk you through the obvious pitfalls, but it isn't as simple as just saying "I'm not eating right now."

So the traditional trade-off in labor and knowledge:

  • Intermittent fasting is usually much easier to introduce into your life, but has far less scientific support or a body of research to indicate the optimum methodology.

  • Calorie restriction requires more initiative to organize, but has a great weight of science backing it up, and a wide range of resources based on decades of practical experience.

Given what I know of human nature, I suspect that intermittent fasting will rapidly become more popular than calorie restriction as soon as it accumulates a little more research in mammals than presently exists.


Scientists have known for many years that calorie restriction in the one true form of weight management that will 'work' and continue to work. The problem is that most people can not stay on a calorie restricted diet because they are hungry all the time. I look forward to learning more about intermittent fasting as the data becomes available.

Posted by: Vicki Zerbee at February 16th, 2009 8:27 PM

I'm wondering how closely fasting is related to accompanying binging. It seems it would be too easy to rebound and lose track of total calories consumed with such a program. Steady controlled eating to keep the blood sugar levels even makes more sense to me.

Posted by: shegeek at February 16th, 2009 11:58 PM

Is there any research about intermittent fasting (frequency, total , juice, water)? If there is any reason to believe that even some of the benefits of calorie restriction are provided by intermittent fasting, I'm interested. Are there any practicioners of intermittent fasting who blog, or otherwise document their experiences?

Posted by: Ralph at February 17th, 2009 10:57 AM

Intermittent Fasting has had a few recent studies. The concept was made popular by Ori Hofmekler who wrote a book on the subject, called "Warrior Diet". This is a good book, but his routine is pretty harsh.

Brad Pilon, on the other hand has an entire book around the concept of fasting twice per week called Eat Stop Eat. I have recommended this book to people who visit my site. Hundreds have purchased this book from my recommendation and have achieved great results.

I have been eating this way for close to a year and it has kept me around 6%-8% body fat year round.

The Study was called: "The Metabolic Effects of Short Periods of Fasting in Humans and its Potential Application in Weight Loss"

His book is based on the topic.

The best study I have read regarding low calorie diets was called..."Effects of Resistance vs. Aerobic Training Combined With an 800 Calorie Liquid Diet on Lean Body Mass and Resting Metabolic Rate"

I have a great discussion going on my blog about the subject.

Anyway...great conversation you have going here.


Posted by: Rusty - Fitness Black Book at February 19th, 2009 10:38 AM

ive been experimenting with success for almost six month. i find its been to blend my approach from day to day, even week to week. my blog keeps me focused and accountable. someday ill want to look back at my stuggles. although i must say ive adapted well, and rarely stuggle with this lifestyle. its much easier than my old insulin spiking days!

Posted by: rachel at May 28th, 2009 12:35 PM

The sources of the fat epidemic:
1. Promiscuous breeding. The result is abnormally
large and abnormally small children. In plain English - the kids are really messed up.

2. Sitting in a chair all day long. No exercise.

3. Cows that are fed growth hormones. This is OK
as long as nobody eats the meat.

Posted by: Louis Parker at June 7th, 2009 7:55 PM

I haven't made this part of a regular routine, but I've done it sporadically and can definitely see the advantages. The days I do fast (very intermittently), I generally feel pretty good.

Nice discussion.

Posted by: Greg at August 23rd, 2009 8:04 PM

Intermittent fasting works for me. I've been practising it since 2006 as to have one meal a day. Calorie restriction is not a problem for me, as I just eat as usual. My appearance and health had greatly improved since then. It has however slight implication on my lifestyle, as I have to alert my friends that I eat one meal a day and if they want to eat with me, they have to reserve my diary in advance.

Posted by: Anna at January 24th, 2010 7:17 PM

I practice intermittent fasting since 2010 and more rigorously since late 2011. I'm 30 years old and most of my health indicators are optimal according to my doctor. I've lost 20 pounds since I’ve started it coupled with light exercise and nutrients supplementation. Basically my routine consists of drinking water only from the time I wake up until I get to sleep one day per week. As claimed in the article it is pretty easy to follow even under a busy and unpredictable schedule.

Posted by: Guilherme at June 8th, 2012 12:34 PM

For me intermittent fasting is much easier than calorie restriction (eating normal frequency but less at every meal):

1. Skipping breakfast everyday and having black coffee is simple, no hunger issues or social issues.

2. My appetite starts to kick in when I start to eat so the eat-but-eat-less approach is painful - much easier to not start in the first place.

3. Continuing to skip one or more meals ( if I want to) is easy as the appetite has not kicked in.
Eg at work I can skip lunch have another black coffee and go for a walk.

4. Have dinner with family/friends in the evening ( real food, not processed food).If I'm on my own I can easily choose to eat dinner ( maybe the first meal if the day) or skip it ( again the appetite is still minimal).

5. Calorie restriction is almost torture to me - get the appetite started by eating- then stop eating when you Only just get the taste for eating! Fasting : I'm not hungry any way and stay that way until I start to eat and when I do eat a normal sized meal is enough ( some times more but more often less than a non-fasted meal).

6 For me the key to no hunger and clear mind is to stay active during the fast - no energy issues, no brain fog, and I don't feel hungry or think about food ( a lot of work gets done too :) - physical work or a gym workout fasted feels good ( better than non-fasted).

7. It just seems to work for me. I didn't need to loose weight at all but wanted a better body composition and other reported health benefits, this method has meant I've lost body fat and increased muscle mass (total body weight is the same - if not a little heavier)- who'd have thought you could grow muscle mass and feel better ( stronger, more clear headed and more energetic) by eating less often :)

Posted by: EatMoveSleep at April 19th, 2013 6:59 PM

there is intermittent fasting in our religion.
it's done every year for 30 days.

religious method is;
you can eat until sunrise. you stop eating until sundown.
(0am)--free to eat---(sunrise )----fasting ------(sundown)--- free to eat---(24pm)

how we apply.
0am---pre-sunrise meal--(sunrise)--fasting---sundown--(after-sundown-meal) ---(24pm)

Posted by: ert at August 24th, 2015 3:43 AM
Comment Submission

Post a comment; thoughtful, considered opinions are valued. New comments can be edited for a few minutes following submission. Comments incorporating ad hominem attacks, advertising, and other forms of inappropriate behavior are likely to be deleted.

Note that there is a comment feed for those who like to keep up with conversations.