New Study: Is a Calorie a Calorie?

A new study in JAMA led by Dr. Cara B. Ebbeling and colleagues purports to challenge the idea that all calories are equally fattening (1).  Let's have a look.  When thinking about the role of calorie intake in body fatness, there are basically three camps:

1.    Calories don’t matter at all, only diet composition matters.
2.    Calories are the only thing that matters, and diet composition is irrelevant.
3.    Calories matter, but diet composition may also play a role.

The first one is an odd position that is not very well populated.  The second one has a lot of adherents in the research world, and there’s enough evidence to make a good case for it.  It’s represented by the phrase ‘a calorie is a calorie’, i.e. all calories are equally fattening.  #1 and #2 are both extreme positions, and as such they get a lot of attention.  But the third group, although less vocal, may be closest to the truth. 
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Don’t judge too soon*

SCREENING is always controversial. It has the capacity to convert a person into a patient even though they may feel perfectly well.

It can label a person with a disorder — hypertension or whatever.

Accumulated wisdom distilled from a vast literature has applied a brake on the earlier enthusiasm for screening, although once in a while a fresh outbreak of screening enthusiasm pops up.

Before embarking on screening, the research data caution us to ask questions and provide answers on issues such as, if we find something during a screening test, what does it mean? Who will follow up abnormalities detected at screening?

At a health system and policy level we ask, how does the cost and effectiveness of a screening program compare with those of treatment programs competing for scarce health dollars?

“First do no harm” should be the first priority applied to all screening.

In 2002, the NHMRC published a report on screening children. Under the leadership of paediatrician Professor Frank Oberklaid from Melbourne, the 250-page report considered all the commonly recommended screening tests for children — hearing, hips, hypothyroidism and many more — and explored the available data. Suffice to say that evidence for the value of many screening tests was scant.

By a complex policy pathway, the $25 million Healthy Kids Check, introduced nationally in 2008, is under revision to align it more closely with evidence of effect.

Under the revision, the age at which children are assessed will change from 4 to 3 years and, according to a report in The Australian, it will “check the child’s immunisation status, allergies, height and weight and ask parents if they had any concerns about their child’s behaviour”.

Professor Oberklaid and colleagues continue to advise on the content and form of this program. In the report in The Australian it said the assessment “involves checking the child’s progress against a validated instrument of child development”.

“Each of the criteria to be used was based on peer-reviewed evidence that has been ‘solidly tested’ and used in the US, Britain, and sometimes in Australia”, the newspaper reports Professor Oberklaid as saying.

Great concern was raised by American psychiatrist Professor Allen Frances, while visiting Australia, about “an explosion of false diagnoses that would see youngsters overmedicated and labelled with a mental illness for life”, but that seems not to be a major worry with this proposal.

The knowledge and expertise of the group of experts in child mental health advising on this program provides assurance that any check of a child’s mental health and wellbeing as part of the Healthy Kids Check will be based on good evidence. Let’s wait to see their final recommendations before we judge this new initiative.

*This article was previously published in MJA Insight 25/06/12

What Puts Fat Into Fat Cells, and What Takes it Out?

Body fatness at its most basic level is determined by the rate of fat going into vs. out of fat cells. This in/out cycle occurs regardless of conditions outside the cell, but the balance between in and out is influenced by a variety of external factors.  One of the arguments that has been made in the popular media about obesity goes something like this:  


A number of factors can promote the release of fat from fat cells, including:

Epinephrine, norepinephrine, adrenocorticotropic hormone (ACTH), glucagon, thyroid-stimulating hormone, melanocyte-stimulating hormone, vasopressin, and growth hormone

 But only two promote fat storage:

Insulin, and acylation-stimulating protein (ASP)*

Therefore if we want to understand body fat accumulation, we should focus on the latter category, because that's what puts fat inside fat cells.  Simple, right?

Can you spot the logical error in this argument?

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A Pressure Cooker for the 21st Century

Pressure cookers are an extremely useful kitchen tool.  They greatly speed cooking and reduce energy usage by up to 70 percent.  This is because as pressure increases, so does the boiling point of water, which is the factor that limits cooking speed in water-containing foods (most foods).  If it weren't for my pressure cooker, I'd rarely eat beets or globe artichokes.  Instead of baking, boiling or steaming these for 60-90 minutes, I can have them soft as butter in 30.  But let's face it: most people are intimidated by pressure cookers.  They fear the sounds, the hot steam, and the perceived risk of explosion.  I escaped this because I grew up around them.

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New Study Demonstrates that Sugar has to be Palatable to be Fattening in Mice

Dr. Anthony Sclafani's research group just published a study definitively demonstrating that high palatability, or pleasantness of taste, is required for sugar to be fattening in mice (1).  Dr. John Glendinning was lead author. Dr. Sclafani's group has done a lot of excellent research over the years.  Among other things, he's the person who invented the most fattening rodent diet in the world-- the 'cafeteria diet'-- composed of human junk food. 

Mice and rats love sweet food and drinks, just like humans.  If you give them a choice between plain water and sugar water, they'll overconsume the sugar water and become obese.  I have argued, based on a large body of evidence, that the reward value and palatability* of these solutions are important to this process (2, 3, 4).  This is really just common sense honestly, because by definition if the solution weren't rewarding the mice wouldn't go out of their way to drink it instead of water, the same way people wouldn't go out of their way to get soda if it weren't rewarding.  But it's always best to confirm common sense with research.
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Cameron Diaz: The Next Celebrity Nutritionist?

Cameron Diaz is busy with her next project.  Her rep confirms her interest in writing a nutrition book to help young girls.  She wants to use her celebrity for good- to encourage girls not to fixate on being thin but instead just to make healthy choices.

A few thoughts:

Of all the celebrities that I see pitching these types of projects (I'm looking at you Gwyneth Paltrow), Cameron actually seems to model a healthy lifestyle.  She is not too thin, but instead looks muscular and strong.  We always see her keeping active with surfing and regular gym workouts.

It is reported that (in preparation for the book) Cameron will be visiting high schools to talk to teenagers about their food choices and what is important to them.  She wants to get their input, e.g., how do they decide what to eat? Although this work will not be a formal "Needs Assessment", I like that Cameron will be out in the community and talking to the teenagers who are the focus of her book.  Doing formative work before a project that engages your audience is incredibly important in public health.  Hearing and seeing what the health problem/s look like first hand allow us to craft more effective interventions.  So I applaud Cameron for planning to do this outreach versus just planning to write a book that may or may not address the challenges faced out in communities. For example, Cameron can discuss the importance of choosing fruit over potato chips, but if a teenager does not have access to affordable fresh fruit in their neighborhood, then the recommendation is not helpful.

One challenge to this effort is that even though Cameron appears to model a healthy lifestyle, she is still a member of the Hollywood community that has contributed to setting an unrealistic standard for beauty.  We have seen her on numerous magazine covers looking very thin and of course airbrushed.  In public health, we always have to think- "is this the right spokesperson"?  It is important to know how teenage girls view Cameron.  Do they see her as part of the problem?  Or part of the solution?

Another challenge is that (from my perspective), celebrity "nutritionists" do not have the best track record for safety and accuracy.  Take Cameron's friend Gwyneth Paltrow.  She has regularly promoted nutrition strategies like detox cleanses and gluten-free diets.  Her extreme choices do not send a message of moderation to teenage girls.  In addition, Gwyneth's cover photos also contribute to the unrealistic standard for beauty.

As I've discussed many times on this blog, celebrities can be an incredible resource for public health.  They have a visible platform and extensive reach to many of our audiences.  However, that can work for us or against us based on the accuracy and relevancy of their messages.  It is imperative that they work closely with clinicians (e.g., physicians, nutritionists) and public health practitioners to craft the messages and design outreach programs.

What do you think about Cameron writing a nutrition book?

Sugar Intake and Body Fatness in Non-industrial Cultures

Around the world, non-industrial cultures following an ancestral diet and lifestyle tend to be lean. When they transition a modern diet and lifestyle, they typically put on body fat and develop the classic "diseases of civilization" such as diabetes and cardiovascular disease.  If we can understand the reasons why this health transition occurs, we will understand why these problems afflict us today.  Research has already identified a number of important factors, but today I'm going to discuss one in particular that has received a lot of attention lately: sugar.

There's an idea currently circulating that sugar is the main reason why healthy traditional cultures end up obese and sick.  It’s easy to find non-industrial cultures that are lean and don’t eat much sugar, and it’s easy to find industrial cultures that are obese and eat a lot of it.  But many factors are changing simultaneously there.  We could use the same examples to demonstrate that blue jeans and hair gel cause obesity.  If sugar is truly the important factor, then cultures with a high sugar intake, but an otherwise ancestral diet and lifestyle, should also be overweight and sick.  Let’s see if that's true. 

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Calories Still Matter

The Centers for Disease Control's NHANES surveys documented a massive increase in obesity in the United States between the 1960-62 and 2007-2008 survey periods (1).  In 1960, 13 percent of US adults were obese, while in 2008 that number had risen to 34 percent.  The prevalence of extreme obesity increased from 0.9 to 6.0 percent over the same time period!

Something has changed, but what?  Well, the most parsimonious explanation is that we're simply eating more.  Here is a graph I created of our calorie intake (green) overlaid on a graph of obesity prevalence (blue) between 1970 and 2008:

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