The Body Fat Setpoint

One pound of human fat contains about 3,500 calories. That represents roughly 40 slices of toast. So if you were to eat one extra slice of toast every day, you would gain just under a pound of fat per month. Conversely, if you were to eat one fewer slice per day, you'd lose a pound a month. Right? Not quite.How is it that most peoples' body fat mass stays relatively stable over long periods of time, when an imbalance of as little...

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Rabbits on a High-Saturated Fat Diet Without Added Cholesterol

I just saw another study that supports my previous post Animal Models of Atherosclerosis: LDL. The hypothesis is that in the absence of excessive added dietary cholesterol, saturated fat does not influence LDL or atherosclerosis in animal models, relative to other fats (although omega-6 polyunsaturated oils do lower LDL in some animal models). This appears to be consistent with what we see in humans.In this study, they fed four groups...

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What's the Ideal Fasting Insulin Level?

[2013 update.  I'm leaving this post up for informational purposes, but I think it's difficult to determine the "ideal" insulin level because it depends on a variety of factors including diet composition.  Also, insulin assays are not always comparable to one another, particularly the older assays, so it's difficult to compare between studies]Insulin is an important hormone. Its canonical function is to signal cells to absorb glucose from the bloodstream, but it has many other effects. Chronically elevated insulin...

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The Dirty Little Secret of the Diet-Heart Hypothesis

The diet-heart hypothesis is the idea that saturated fat, and in some versions cholesterol, raises blood cholesterol and contributes to the risk of having a heart attack. To test this hypothesis, scientists have been studying the relationship between saturated fat consumption and heart attack risk for more than half a century. What have these studies found?The large majority of observational studies have found no connection between habitualsaturated fat consumption and heart attack risk. The scientific literature contains...

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Butyric Acid: an Ancient Controller of Metabolism, Inflammation and Stress Resistance?

An Interesting FindingSusceptible strains of rodents fed high-fat diets overeat, gain fat and become profoundly insulin resistant. Dr. Jianping Ye's group recently published a paper showing that the harmful metabolic effects of a high-fat diet (lard and soybean oil) on mice can be prevented, and even reversed, using a short-chain saturated fatty acid called butyric acid (hereafter, butyrate). Here's a graph of the percent body fat over...

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Malocclusion: Disease of Civilization, Part IX

A SummaryFor those who didn't want to wade through the entire nerd safari, I offer a simple summary.Our ancestors had straight teeth, and their wisdom teeth came in without any problem. The same continues to be true of a few non-industrial cultures today, but it's becoming rare. Wild animals also rarely suffer from orthodontic problems.Today, the majority of people in the US and other affluent nations have some type of malocclusion,...

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Malocclusion: Disease of Civilization, Part VIII

Three Case Studies in OcclusionIn this post, I'll review three cultures with different degrees of malocclusion over time, and try to explain how the factors I've discussed may have played a role.The Xavante of Simoes LopesIn 1966, Dr. Jerry D. Niswander published a paper titled "The Oral Status of the Xavantes of Simoes Lopes", describing the dental health and occlusion of 166 Brazilian hunter-gatherers from the Xavante tribe (free full text). This tribe was living predominantly according to tradition, although they had begun...

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Malocclusion: Disease of Civilization, Part VII

Jaw Development During AdolescenceBeginning at about age 11, the skull undergoes a growth spurt. This corresponds roughly with the growth spurt in the rest of the body, with the precise timing depending on gender and other factors. Growth continues until about age 17, when the last skull sutures cease growing and slowly fuse. One of these sutures runs along the center of the maxillary arch (the arch in the upper jaw), and contributes...

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Malocclusion: Disease of Civilization, Part VI

Early Postnatal Face and Jaw DevelopmentThe face and jaws change more from birth to age four than at any other period of development after birth. At birth, infants have no teeth and their skull bones have not yet fused, allowing rapid growth. This period has a strong influence on the development of the jaws and face. The majority of malocclusions are established by the end this stage of development. Birth is the point at which the...

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Malocclusion: Disease of Civilization, Part V

Prenatal Development of the Face and JawsThe structures of the face and jaws take shape during the first trimester of pregnancy. The 5th to 11th weeks of pregnancy are particularly crucial for occlusion, because this is when the jaws, nasal septum and other cranial structures form. The nasal septum is the piece of cartilage that forms the structure of the nose and separates the two air passages as they enter the nostrils. Maternal Nutritional Status Affects Fetal Development Abnormal nutrient status can lead to several...

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Impressions of Hawai'i

I recently went to Hawai'i for the American Society of Human Genetics meeting in Waikiki, followed by a one-week vacation on Kaua'i with friends. It was my first time in Hawai'i and I really enjoyed it. The Hawai'ians I encountered were kind and generous people.Early European explorers remarked on the beauty, strength, good nature and exellent physical development of the native Hawai'ians. The traditional Hawai'ian diet consisted mostly...

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Butter vs. Margarine

I came across an interesting study the other day, courtesy of Dr. John Briffa's blog. It's titled "Margarine Intake and Subsequent Coronary Heart Disease in Men", by Dr. William P. Castelli's group. It followed participants of the Framingham Heart study for 20 years, and recorded heart attack incidence*. Keep in mind that 20 years is an unusually long follow-up period.The really cool thing about this study is they also tracked...

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