Thursday, June 28, 2012

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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Monday, June 25, 2012

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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Tuesday, June 19, 2012

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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Monday, June 18, 2012

The lowest-mortality BMI: What is its relationship with fat-free mass?

Do overweight folks live longer? It is not uncommon to see graphs like the one below, from the Med Journal Watch blog (), suggesting that, at least as far as body mass index (BMI) is concerned (), overweight folks (25 < BMI < 30) seem to live longer. The graph shows BMI measured at a certain age, and risk of death within a certain time period (e.g., 20 years) following the measurement. The lowest-mortality BMI is about 26, which is in the overweight area of the BMI chart.

Note that relative age-adjusted mortality risk (i.e., relative to the mortality risk of people in the same age group), increases less steeply in response to weight variations as one becomes older. An older person increases the risk of dying to a lesser extent by weighing more or less than does a younger person. This seems to be particularly true for weight gain (as opposed to weight loss).

The table below is from a widely cited 2002 article by Allison and colleagues (), where they describe a study of 10,169 males aged 25-75. Almost all of the participants, ninety-eight percent, were followed up for many years after measurement; a total of 3,722 deaths were recorded.

Take a look at the two numbers circled in red. The one on the left is the lowest-mortality BMI not adjusting for fat mass or fat-free mass: a reasonably high 27.4. The one on the right is the lowest-mortality BMI adjusting for fat mass and fat-free mass: a much lower 21.6.

I know this may sound confusing, but due to possible statistical distortions this does not mean that you should try to bring your BMI to 21.6 if you want to reduce your risk of dying. What this means is that fat mass and fat-free mass matter. Moreover, all of the participants in this study were men. The authors concluded that: “…marked leanness (as opposed to thinness) has beneficial effects.”

Then we have an interesting 2003 article by Bigaard and colleagues () reporting on a study of 27,178 men and 29,875 women born in Denmark, 50 to 64 years of age. The table below summarizes deaths in this study, grouping them by BMI and waist circumference.

These are raw numbers; no complex statistics here. Circled in green is the area with samples that appear to be large enough to avoid “funny” results. Circled in red are the lowest-mortality percentages; I left out the 0.8 percentage because it is based on a very small sample.

As you can see, they refer to men and women with BMIs in the 25-29.9 range (overweight), but with waist circumferences in the lower-middle range: 90-96 cm for men and 74-82 cm for women; or approximately 35-38 inches for men and 29-32 inches for women.

Women with BMIs in the 18.5-24.9 range (normal) and the same or lower waists also died in small numbers. Underweight men and women had the highest mortality percentages.

A relatively small waist (not a wasp waist), together with a normal or high BMI, is an indication of more fat-free mass, which is retained together with some body fat. It is also an indication of less visceral body fat accumulation.

Wednesday, June 13, 2012

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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Saturday, June 9, 2012

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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Tuesday, June 5, 2012

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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Monday, June 4, 2012

How to make white rice nutritious

One of the problems often pointed out about rice, and particularly about white rice, is that its nutrition content is fairly low. It is basically carbohydrates with some trace amounts of protein. A 100-g portion of cooked white rice will typically deliver 28 g of carbohydrates, with zero fiber, and 3 g of protein. The micronutrient content of such a portion leaves a lot to be desired when compared with fruits and vegetables, as you can see below (from Keep in mind that this is for 100 g of “enriched” white rice; the nutrients you see there, such as manganese, are added.

White rice is rice that has had its husk, bran, and germ removed. This prevents spoilage and thus significantly increases its shelf life. As it happens, it also significantly reduces both its nutrition and toxin content. White rice is one of the refined foods with the lowest toxin content.

Another interesting property of white rice is that it absorbs moisture to the tune of about 2.5 times its weight. That is, a 100-g portion of dry white rice will lead to a 250-g portion of edible white rice after cooking. This does not only dramatically decrease white rice’s glycemic load () compared with wheat-based products in general (with some exceptions, such as pasta), but also allows for white rice to be made into a highly nutritious dish.

If you slow cook almost anything in water, many of its nutrients will seep into the water. All you have to do is to then use that water (often called broth) to cook white rice in it, and you will end up with highly nutritious rice. Typically you will need twice as much broth as rice, cooked for about 15 minutes – e.g., 2 cups of broth for 1 cup of rice.

You can add meats to the white rice, such as pulled chicken or shrimp; add some tomato sauce to that and you’ll make it a chicken or shrimp risotto. You can also add vegetables to the rice. If you want your rice to have something like an al dente consistency, I recommend doing these after the rice is ready; i.e., after you cooked it in the broth.

For the white rice-based dish below I used a broth from about two hours of slow cooking of diced vegetables; namely red bell peppers, carrots, celery, onions, and cabbage. After cooking the rice for 15 minutes, and letting it "sit" for a while (another 15 minutes with the pan covered), I also added the vegetables to it.

As a side note, the cabbage and onion tend to completely dissolve after 1 h or so of slow cooking. The added vegetables give the dish quite a nutritional punch. For example, the cabbage alone seems to be a great source of vitamin C (which is not completely destroyed by the slow cooking), the anti-inflammatory amino acid glutamine, and the DNA repair-promoting substance known as indole-3-carbinol ().

The good folks over at the Highbrow Paleo group on Facebook () had a few other great ideas posted in response to my previous post on the low glycemic load of white rice (), such as cooking white rice in bone broth (thanks Derrick!).