Monday, October 06, 2008

The Real Reason Diets Don't Work

It was back on March 12 of 2007 that I first wrote about the now famous A to Z weight loss trial (you can see my original blog post HERE ).

In this ground breaking study, 311 overweight women were recruited to follow one of the following popular diet programs: The Atkins Diet, The Zone Diet, the LEARN diet or the Ornish Diet.

To start the study, each woman was given a copy of the popular diet book that she was randomly assigned to follow.

Then, to make sure she was an “expert” on her program before she started dieting, each woman attended a series of 8 classes (each lasting an hour) explaining exactly how to follow her assigned diet.

(Side note- This just shows how OCE these diets are considering that it takes EIGHT classes for these women to know how to properly follow each diet!)

After the courses were completed the women then set off to follow their assigned diet plan for a total of 1 year.

The results were pretty much exactly what I expected – everybody lost a lot of weight in the first two months, after that the diets tended to even out and by the end of the trial the weight loss was far from impressive – none of the groups averaged more than 10 pounds of weight loss after an entire year of dieting.

And while many people used this study to ‘prove’ that diets simply didn’t work, or that the body somehow adapted to dieting, my take was much simpler – Firstly, this trial is in agreement with most research that shows it is very hard to accurately measure how many calories a person eats in a day, and secondly I thought that these results showed that the number one reason diets fail is compliance.

In other words, the more complicated and the more rigid the diet is (or the more OCE it is), the more likely it is going to fail in the long term. – People just can’t stick to these types of diets for long periods of time.

Apparently I wasn’t alone with my analysis.

In a study published in the International Journal of Obesity titled “Dietary adherence and weight loss success among overweight women: results from the A to Z weight loss study” researchers re-examined the A to Z weight loss trial to see if there was an association between the level of compliance and the amount of weight that was lost.

Guess what they found?

Astonishingly only ONE subject in the ENTIRE study followed the diet as directed for the whole 12 months. This means that every other subject was not following her assigned diet properly at some point during the research trial!

The researchers also found that adherence was significantly correlated with 12-month weight change for all three-diet groups. So the better a woman was at following her diet, the more weight she lost.

The fact that adherence was so low is very interesting considering that these women spent eight class sessions reviewing their assigned diets with a registered dietitian before they even started the diet…you can imagine what adherence must be like for someone who simply bought one of those books, read it cover to cover and then gave it a try!

The findings from this follow-up analysis also suggest that the difference in dietary macronutrients had only negligible effects on the participants weight loss success.
The bottom line is that you can generally figure out how successful a diet will be by looking at how complicated it is.

More rules = more complicated = low chance of success

Less rules = less complicated = high chance of success

In my opinion weight loss can be incredibly simple if you let it.

Find the easiest, most comfortable way to reduce the total amount of calories that you eat. The less intrusive a diet is on your lifestyle the greater chance you have of sticking to it long term.

For me, this is flexible intermittent fasting. After all if you can fast for 24 hours once, you know you will always be able to do it. Some fasts maybe harder or easier than others, but you know you can do it!

Obsessive Compulsive Eating habits that make diets complicated and difficult spell doom for long-term weight loss.


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Anonymous said...


I arrived at the site after hearing about your book (which I plan to pick up).

I was wondering what your educational background is? Are you an accredited dietician?

BridesMadeFit said...

I totally agree that healthy nutrition can be simple. My belief is that accountability is the deciding factor of whether someone will fall off the wagon or not. Great job helping spread the word on this and great blog!

Brad Pilon said...

Hi Anon,

I Completed my Bachelor of Applied Science in Human Nutrition in 2000 after which I spent 7 years working in R&D in the sports supplement industry.

In 2007 I returned to school and completed my MSc in Human Biology and Nutritional Science where I concentrated on the metabolic effects of short term fasting in humans.

I am not a dietitian (I have no interest in working in a hospital setting or in community health)

I hope this helps,


Brad Pilon said...


Thanks for the kind words.


Nathan said...

Hi Brad,

Sorry for the slightly unrelated question, but I was wondering if fasting will affect you differently during your period (sorry to be so blunt). Is it a good idea to just eat normally if you tend to get really weak during this time frame, and then resume ESE the next week?


Brad Pilon said...

Hi Nathan,

The whole point of flexible intermittent fasting is that you have the ability to adapt to your current situation.

I would try both fasting and not fasting during a persons period. which ever feels better is what I would do.

If the time during a period is simply not a good one for fasting, then just skip the fasts for those days.

Keep it flexible and keep it simple.


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Jordon said...

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