Wednesday, 1 August 2012

Does diet composition have an impact on weight loss?

Hello friends!  Time for another enthralling blog post.  Today's topic may or may not hit close to home.  I've been asked enough about weight loss that I figured it is finally time to write about it.

As much as we like to pursue healthy living to help us feel good, prevent disease, improve quality of life and prolong life, often we simply just want to lose some weight.

And as you all know, there are way too many quick fixes.  While we would like to believe there is some magic weight loss formula, the answer, at the end of the day, comes down to calories in and calories out.

However, an area I often get questions about relates to the composition of those calories coming in.  If we are looking at the issue from a pure weight loss standpoint, does it matter what type of calories we consume?  That's what this blog will explore.


A great 2012 study looked at this issue in a very clear way.  Participants were randomized into 4 groups which followed 4 very distinct weight loss diets.  The caloric content was the same, just the composition varied.
  • Two protein amounts were examined (25% of diet vs. 15%)
  • Two fat amounts were examined (40% of diet vs. 20%)
  • 4 carbohydrate amounts were compared (35% up to 65%)
The study examined the following parameters to monitor the progress of the participants:
  • total fat loss
  • lean mass loss
  • abdominal fat loss
  • subcutaneous fat loss (the stuff right under your skin)
  • visceral fat loss (the fat that coats your organs)

This is what they found:

There was NO difference between groups.  

It simply didn't matter what their dietary composition was, it only mattered if they were consuming a calorie-controlled diet.  All participants showed equal fat loss, weight loss and lean mass loss.  All participants lost equal amounts of abdominal fat, subcutaneous fat and visceral fat. 

This study confirms what many others have: weight loss in otherwise healthy individuals comes down to calories in and calories out.

Practical Implication:  

While the answer to weight loss may be as simple as calories in vs. calories out, I am not going to begin to pretend that the issue is that simple in the real world.  When addressing an individual who is trying to pursue weight loss, it is undoubtedly a complex and multifactorial challenge.  Telling someone to eat less and excercise more simply will not work- they already know that!  It's like telling a smoker, "Hey, it's bad for you, so you should quit."

However, what this study does show is that while calories in vs. calories out may not be the answer, it must become the end goal for anybody trying to lose weight.  Whether that means changing social habits, seeking psychological counseling, cutting down on work hours to allow for more exercise; the process will be individualized based on personal needs.  That being said, all of these changes lead to two things: either start burning more calories, or start eating fewer calories.

This study also shows that high protein diets (such as Atkins) really do not have the physiological implications they claim to.  These diets may still work, but most likely because they indirectly result in caloric restriction.  Heck, if you're anything like me, cutting out carbs would result in me consuming about 10 calories/day.  

Also, keep in mind this calorie in vs. calorie out thing does NOT even begin to address the nutritional aspect of what we eat.  For instance, Weight Watchers is actually decently effective in helping people lose weight.  However, the problem I have with it is if you chose to consume empty calories (i.e. 4 beers), then you are going to be forced to skip your nutrient-rich dinner; this is not good!


Weight loss is a very complicated, but at the same time, a very simple issue.  The end goal: reduce caloric intake and increase exercise.  The complicated part is figuring out how you get yourself there.


  1. Such analysis in my opinion are dangerous, as they limit the variables and the end result is therefore aimed at a specific result. What about the complexity of the Glycemic Index. What about stress, what about eating smaller meals, and eating every 2-3 hours. In short there are 4 basic needs to health, and weight loss. If the focus is only weight loss, you have already lost.

  2. Thanks for the comment Pat!

    This analysis definitely is not dangerous as they measured exactly what they set out to: weight loss vs. calorie content. Along with you and I, the authors of this study fully understand that weightloss is not the only component to health.

  3. Thanks for posting, Sean :) I think another important consideration is how HAPPY the individual is while being on a calorie-restricted diet... If people feel deprived and hungry there's a good chance the diet will fail and/or lead to bingeing and feelings of guilt or failure.

    So the while the source of calories may not be the bottom line for weight loss, considering the macronutrient balance and water and fibre content of one's calories can be extremely important for satiety, pyschological and emotional well-being, and overall success of the diet.

  4. Thanks for the comment Mary Anne! I couldn't agree more, and that is exactly what I tried to address in the last couple of paragraphs.

    This research isn't claiming calories in/out is all you need to address, it is simply elucidating the bottom line of weight-loss where there seems to be some confusion: the misconception (for some) that, in isolation, 1000 calories of protein will not pack on the pounds in the same way 1000 calories of carbs will. Studies like this just help to re-enforce the importance of actually reducing calories, not simply changing them.

    BUT, like you said, feeling nourished, happy, energetic etc is the only way these types of changes are sustainable (and healthy) long term.

  5. Part 1 of 2

    The study cited uses four sets of cohorts varying the percentages of carbs, protein and fat between them. The study concludes there was no difference in weight loss, fat loss and lean mass loss between the four groups. All participants lost an equal amounts of adominal fat, subcutaneous fat and visceral fat - no less and more importantly no more. The blog however goes further in claiming the study confirms that weight loss comes down to calories in and calories out. The study does not make that claim and certainly makes no claim between cause and effect. The blog does. Mass population studies cannot make cause and effect claims - they can only make reasonable hypothesis which need then to be verified by in this case understanding the chemistry of metabolism.

    The blog makes the claim that many studies exist to support the calories in vs calories out claim. Mass population studies may exist but again they by definition cannot make cause and effect claims. I rather doubt there is another type of study that supports this blog claim.

    The study does not address the substantial differences between how fat, protein and carbohydrates are metabolized. The science has come so far to show that carb consumption causes an increase of insulin secretion. Insulin is the primary regulator of fat storage. When insulin levels increase, we accumulate fat in our adipose tissue and insulin prevents it from being released. When insulin levels fall, we release fat from our fat tissue and use it for fuel. Once we begin to understand this, we can begin to understand the impact of carbohydrate on weight gain or loss. Neither fat nor protein invoke this response.

    The lowest percentage of carbs in the study's groups was 35%. This is enough to stimulate the insulin response and depending on the period of time over the day the carbs are consumed, keep the insulin elevated. To support a hypothesis the blog makes using this type of study, the authors would have needed to expand the ranges of all three factors - fat, protein and carbohydrates - to what is reasonably possible, that is closer to 0% and 100%.

    (Some information in this entry comes from two books by Gary Taubes - Good Calories, Bad Calories and Why We Get Fat.)

  6. Part 2 of 2

    With respect to weight loss, reducing the answer to 'calories in vs. calories out' or restricted calories is a cruel hoax. It simply does not work. First it fails to recognize the impact of carbohydrates on metabolism and its impact on weight gain. Second, these diets fail because they reduce energy expenditure. George Bray, one of the authors referenced in the citation has demonstrated "that people on low-calorie diets actually develop lower total body energy requirements and thus burn fewer calories". Bray himself has published an article "The Myth of Diet in the Management of Obesity". The study itself indicates 40% of participants regained their weight after two years. The third and primary reason diets fail is that they invoke a state of deprivation - one may tolerate hunger for the length of time one's internal fortitude has the resolve, but one cannot tolerate hunger for life.

    To lose weight, we are being told to eat less (decrease calories) and to exercise more (burn calories) the very same things we'd do to make ourselves hungry, to build up appetite and to eat more. Chris Williams who blogs under the name Asclepius had the insight that the existence of an obesity epidemic coincident with 50 years of advice to eat less and exercise more looks less paradoxical.

    With respect to exercise, we base our belief in the weight reduction properties of exercise on the assumption that we can increase our energy expenditure (calories out) without having to increase our energy intake (calories in). Keep this up long enough and you can loose weight as long as you do not change your diet. Is this a reasonable expectation? Increase your activity will work up your appetite, make you hungrier and the evidence is that you will increase your calorie consumption to compensate.

    Among the many benefits of exercise, weight loss should not be considered one of them. Exercise does not cause us to loose weight long-term. Rather it makes us hungry. To invoke exercise as part of the solution to weight loss is in my opinion not substantiated.

    (Some information in this entry comes from two books by Gary Taubes - Good Calories, Bad Calories and Why We Get Fat.)

  7. Hey Jerry, thanks for the comment!

    Firstly, the blog conclusion was not an extrapolating from what was discussed in the study.

    Secondly, as I stated in the blog: weight loss is a multifactorial process. It's great that you have found Taubes' book so convincing and it has worked for you! If avoiding carbs is your way of managing your hunger, and reducing your caloric intake, and the science makes sense to you, then then that's great! You have figured out your multifactorial process.

    However, it just does not apply to everybody (especially to people who are active, and require carbs to sustain their activity level).

    Hunger and fat storage is much more complicated than carbs causing an insulin spike. Your insulin and hunger argument is one that all low-carb lovers use (and it may be true for some, but not everybody). This is precisely what the study presented in this blog debunks. Carbs don't cause obesity, too many calories do.

    The points you bring up do not really go against anything the article or blog state, you bring up questions of sustainability of different weight loss solutions. And, well, that is just too complicated for one blog.

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