Monday, October 5, 2009

Intermittent Fasting and "Starvation Mode"

This is a guest post from Brad Pilon, the author of Eat Stop Eat (I interviewed Brad a while ago)

You may have read a few times that fasting causes your body to enter starvation mode, which shuts down fat burning as your body tries to hold onto its precious fat stores.....that is all rubbish as Brad explains!

The theory of Starvation Mode is something that fuels Obsessive Compulsive Eating in North America and throughout the world.

To use a very basic definition, Starvation mode is when your metabolism supposedly slows down when you don’t eat enough calories. More often than not this definition is used to support very complex diet programs.

These diets will tell you that not eating enough food will cause you to store more fat. Right after delivering this pseudo-science message of fear they then tell you the only solution is to keep eating, and here is the catch, you must eat the special foods they recommend.

This is just another example of fear mongering and confusion created by the food, diet and supplement industry that ultimately leads to obsessive compulsive eating.

They are actually trying to tell you that eating less food won’t help you lose weight, and in fact might actually cause you to gain weight - Fear mongering at its best.

The truth is a large body of scientific research shows you can eat very low calories for extended periods of time with no change in your metabolism and, no decrease in muscle mass, as long as you do some form of resistance training (I cover a large part of this research in Eat Stop Eat).

This is one of the major reasons why so many people are afraid that eating too much food or too little food will have a negative effect on their metabolism.

In my opinion the scientific research is clear, you can eat very low calorie for an extended period of time. As long as you do some weight training the only thing that is going to happen is an impressive amount of fat loss.

And if the existing body of research wasn’t enough to convince you, here is more proof that you can lose significant amounts of weight without losing muscle mass or damaging your metabolism as long as you are using resistance training as part of your weight loss plan.

In a study just published in the Journal of Obesity, researchers examined the effects of losing 25 pounds on 94 women who either

A) Followed a resistance training workout program

B) Followed an aerobic training program

C) Did not workout at all

These women were asked to follow a diet consisting of 800 Calories until they reduced their BMI down to less than 25 (The average 25 pounds of weight loss). The women continued this diet for as long as 5 months straight (not something I would personally recommend without being medically monitored).

The researchers found that the women who were following the resistance training workout program maintained their Fat Free Mass during the time they were on the diet. This means that even though they lost 25 pounds they were able to preserve their muscle mass. Therefore all 25 pounds that these women lost was fat!

They also found the group of women who were following the resistance training workout program preserved their metabolic rate. In other words they did not see any metabolic “slow down” as a result of losing 25 pounds, or from being on a 800 Calorie per day diet for 5 months!

Interestingly, the researchers found decreases in Fat Free Mass in the women who did not workout AND in the women who performed aerobic training.

More evidence that resistance training while following a weight reducing diet program can preserve lean mass and metabolic rate.

This is yet another example of why the Eat Stop Eat combination of flexible intermittent fasting and resistance training can help you lose fat without losing muscle or lowering your metabolism.

Brad Pilon is a nutrition professional with over eight years experience working in the nutritional supplement industry specializing in clinical research management and new product development. Brad has completed graduate studies in nutritional sciences specializing in the use of short term fasting for weight loss.

His trademarked book Eat Stop Eat has been featured on national television and helped thousands of men and women around the world lose fat without sacrificing the foods they love. For more information on Eat Stop Eat, visit


Anonymous said...

What about people who combine aerobic as well as a resistance training workout program. I am a marathon runner, but generally train heavily in the spring/summer. During the fall i like to increase my weight training, but i still run about 30-40 miles a week just to stay in running shape. If i am trying to burn fat and decrease my calories, does it matter that I am doing aerobic training as long as I weight train?

Melanie Milletics said...

I find this really encouraging. I had always assumed the starvation mode theory was fact. Thank you for clearing that up! It also explains that I am not a total anomaly. I can eat just about 1000 calories a day, lose weight, and not rebound. I do strength train as well. I knew that strength training was an integral part of the successful weight loss for women ~ but this puts it all in a new perspective. Now I know, if I'm dieting, I'd better pound the weights!

Chris said...


for specifics on this article I'd advise you to email brad. For my part I'd note that the context here is intermittent fasting not long term low calories diets. I think there is definite value to an occasional fast, but that is different from continual near starvation.

I am less convinced of the health benefits of marathon training, but that is a different issue.

Clamence said...

email him where?

i would like to read this journal of obesity study he cited

Synaura said...

Different body requires different nutrition, so it is advisable to consult first with a physician before taking any supplements. Everyone should bare in mind that aside from taking supplements, one must be conscious of his diet and daily activities to live a healthy lifestyle.
The Right Place. The Right Time

Synaura said...

Different body requires different nutrition, so it is advisable to consult first with a physician before taking any supplements. Everyone should bare in mind that aside from taking supplements, one must be conscious of his diet and daily activities to live a healthy lifestyle.
The Right Place. The Right Time

Bryce said...

I am a big fan of intermittent fasting, but I wonder: does it work because of the reduced calorie intake?

When you fast, your insulin levels are lower for longer. Also, you deplete your glycogen levels, which makes your muscles more sensitive to insulin.

So does fasting work because you're eating less calories? Or, does it work because of the decreased insulin levels associated with not eating for 24 hours, combined with the heightened insulin sensitivity from having depleted glycogen levels that result from the fast.

IF definitely works, but I think the jury is out on why. For my part, I tend to eat more in the 24hours after a fast than I would have otherwise, but I still find that it helps me keep leaner. I don't know whether my theory is right or not, but I have to thank Brad for his contributions.

Yummy said...

Great post!

Chris said...


you can email him at

brad AT

Chris said...


Looking through the research it seems that there are all sorts of hormonal factors that are affected.

Chainey said...

Hi Chris

First of all let me just say that although several of my comments over the last few months have been skeptical/critical, I agree with and am grateful for most of what you say - When I'm silent it's a vote of confidence!

OK, Brad's post: I'm prepared to believe that starvation mode is a myth, but he hasn't really proven it.

First of all there's that big, big proviso that doesn't kick in till the end of paragraph 6 - namely that resistance exercise is mandatory. So, what about all the people who can't or won't do it? Could starvation mode be true for them?

Secondly, the version of starvation mode that I heard is one in which it supposedly kicks in quite quickly, then fades as the body "realises" that there are actually calories coming in, just fewer than it's used to. In that context the study he cites is irrelevent since it covered 5 months! Long enough to adapt to just about anything. So once again I say it's not relevant to the average person who is unlikely to keep up a really rigorous semi fast for months at a time. If the starvation mode exists, it will bother him short-ish term and perhaps sabotage his weight loss efforts within a period of weeks by not allowing any positive feedback on the scale.

Lastly, I kind of switch off when I see someone with a product to sell "dissing" others who have products to sell. All the others are crooks and he's the only straight one. They all want you to "eat the special foods they recommend" but he's completely disinterested (To find out more, get Eat Stop Eat, available at all quality bookstores)

Probably he's on to something, and probably his book is factual and useful, but in this little article he doesn't particularly impress me.

Chris said...

Chainey - i take your points.

With respect to th last one, yes he does have a book to sell. I think it is a pretty good one personally. However, there is a lot of other stuff on fasting on this site that is nothing to do with Brad. Do a search for IF or click here

Stargazey said...

Sorry to be late to the discussion, but as a veteran of the Kimkins wars, I feel it's important to chime in.

I agree with Clamence--we need a link to the study that says a group of women could eat 800 calories per day for five months and maintain their fat-free mass and their metabolic rate. Also with Chainey--apparently this maintenance of fat-free mass required a resistance training workout program. What happened to the women in the other groups?

In 2007, thanks to a cover story on the magazine "Woman's World," approximately 40,000 women signed up for a low-carb, low-fat diet called Kimkins. Calories were mainly from protein sources and were restricted to fewer than 1000 per day. Exercise was optional. Fortunately most of the women who started the diet soon dropped out. For those that stuck with it, a blog called Kimkins Survivors relates the stories of hair loss, loss of libido, heart palpitations, blacking out and many more symptoms. The poster girl for the diet, Christin Sherburne lost 100 pounds but had her health damaged by the diet and found that she could only eat very few calories without re-gaining her weight. Other survivors who post on the Fascination with Kimmer threads at Low Carb Friends relate similar stories about the fact that they are now unable to eat a normal number of calories without gaining weight.

Granted, these women were not supervised by doctors and, as far as we know, were not doing resistance exercise. Granted, these are all anecdotes and not scientific studies. Nevertheless, please be very careful about dismissing the possibility that eating too few calories can put a person into starvation mode.

Chris said...

I'll try to get hold of the study. I'm well aware of kimkins.

The context here is about "starvation mode" and intermittent fasting not long term starvation. If you fast for 24 hours then eat normally you are not going to enter starvation mode.

Stargazey said...

Chris, it sounded to me as though he was dismissing starvation mode as fear mongering, not just in the context of intermittent fasting but also in the practice of eating very low calorie for an extended period of time. Perhaps I am overreacting. If so, I apologize.

Anonymous said...

To this day, we are taught to fear starvation mode and slow metabolism, a state when the body clings on to fats. However, military research proves otherwise!
Starvation mode / slow metabolism - military says no fear