I've put off writing this post for many years because I know it will be controversial. But we're a few days from Christmas, and I also know this post will be a wonderful gift for some people.Chronic or intermittent pain, often located in the back, neck, and/or buttocks, is a major driver of personal suffering and reduced productivity in the US and other affluent nations. While pain can obviously have a variety of structural causes, such as sprained ankles or bruising, garden-variety back pain usually doesn't. I've come to believe that such pain is usually psychosomatic in nature-- in other words, caused by the brain but resulting in physical signs and symptoms in the body. It's widely accepted that a person's mental...
New Evidence Strengthens the Link Between Hypothalamic Injury, Obesity, and Insulin Resistance
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Obesity involves changes in the function of brain regions that regulate body fatness and blood glucose, particularly a region called the hypothalamus. My colleagues and I previously showed that obesity is associated with inflammation and injury of the hypothalamus in rodent models, and we also presented preliminary evidence that the same might be true in humans. In our latest paper, we confirm this association, and show that hypothalamic injury is also associated with a marker of insulin resistance, independently of BMI.IntroductionRead more...
Fat, Added Fat, and Obesity in America
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In the last post, we saw that carbohydrate and particularly sugar intake have been declining in the US since 1999, even as our obesity rate has continued to climb. In this post, let's look at another putative driver of obesity: our fat intake, and especially our intake of added fats like seed oils, butter, and olive oil. Like the graphs in the last post, the data underlying the following graphs come from USDA food disappearance records (not self-reported), and NHANES survey data (1, 2). Also like the last post, the graph of total fat intake is not adjusted for waste (non-eaten food), while the graph of added fat intake is*. As a consequence, the figures for total carbohydrate and total fat intake are higher than actual intakes,...
Carbohydrate, Sugar, and Obesity in America
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We like explanations that are simple, easy to understand, and explain everything. One example of this is the idea that eating carbohydrate, or sugar, is the primary cause of obesity. This lets us point our finger at something concrete and change our behavior accordingly. And it's true enough that it has practical value. But the world around us often turns out to be more complex than we'd like it to be.The CDC recently released its latest data on the prevalence of obesity in the US, spanning the years 2013-2014 (1). These data come from its periodic National Health and Nutrition Examination Surveys (NHANES). Contrary to what many of us had hoped for after a slight decline in obesity in the last survey, the...
Food Reward Friday
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This week's lucky "winner"... the Reese's PBC Burger!!Image credit: The WorksRead more...
Do Processed and Red Meat Cause Cancer?
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Today, the World Health Organization's International Agency for Research on Cancer published a statement in The Lancet detailing its position on the carcinogenicity of processed and red meat (1). The statement, resulting from a meeting of 22 scientists from 10 countries, concluded that processed meat is a group 1 carcinogen, meaning that it is "definitely carcinogenic to humans". They also judged that red meat is a group 2A carcinogen, meaning that it probably causes cancer but the evidence isn't as strong. They're mostly referring to the links between processed and red meat and digestive tract cancer, particularly cancers of the colon and rectum.These statements were met with a media frenzy, and the expected furor from the...
Why Do Girls and Boys Reach Puberty Younger Than They Used To?
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Girls, and probably boys, are reaching puberty years younger than they did in our great-grandparents' generation. Why? There's no shortage of explanations, but the primary reason is probably quite simple.Read more...
Will You Fill Out This Paleo Diet Survey?
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This week, I received an e-mail from a graduate student at Humboldt State University named May Patiño. She asked me to share her online research survey targeted to Paleo dieters. Here are the goals of her research, in her words:The main objective of my study is exploring how the Paleo diet is being implemented in practice. I would like to assess the health outcomes of these practices, as well evaluate how closely they conform to, or deviate from ways this diet is being described in theoretical literature, and implemented in controlled diet trials. I also want to be able to use the data collected to help explain what is driving the popularity of the ancestral health movement. Ultimately, I would like this information...
That Time I Ate Most of a Large Pizza in One Sitting
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Two weeks ago, I had a brush with Extreme Eating. My experience illustrates some important principles of how the brain regulates appetite and body fatness-- and how it reacts to calorie-dense, highly rewarding foods.Read more...
Out for Two Weeks
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I'll be out of town with limited internet until September 27th. Feel free to leave comments, but I won't be able to moderate them until I return. Sorry for the inconvenienc...
How Much Does Sugar Contribute to Obesity?
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Last week, the British Medical Journal published a review article titled "Dietary Sugars and Body Weight", concluding that "free sugars" and sugar-sweetened beverages contribute to weight gain. But what are "free sugars", and why does the scientific literature suggest that the relationship between sugar intake and body weight isn't as straightforward as it may initially appear?Read more...
More Thoughts on the Recent Low-fat vs. Low-carb Metabolic Ward Study
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The recent low-carb vs. low-fat study has provoked criticism from parts of the diet-health community. Let's examine these objections and see how they hold up to scientific scrutiny.Read more...
A New Human Trial Undermines the Carbohydrate-insulin Hypothesis of Obesity, Again
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The carbohydrate-insulin hypothesis of obesity states that carbohydrates (particularly refined carbohydrates and sugar) are the primary cause of obesity due to their ability to increase circulating insulin, and that the solution to obesity is to restrict carbohydrate intake. Numerous studies have tested this hypothesis, more or less directly, in animals and humans. Despite the fact that many of these studies undermine the hypothesis, it remains extremely popular, both in the popular media and to a lesser extent among researchers. A new human trial by Kevin Hall's research team at the US National Institutes of Health offers very strong evidence that the carbohydrate-insulin hypothesis of obesity is incorrect. At the...
Refined Sugar Worsens Blood Lipid Markers of Cardiovascular Disease
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Blood lipids such as LDL and HDL cholesterol are markers of the biological processes that impact cardiovascular disease, and they are commonly measured to assess cardiovascular risk. When we think about the impact of food on blood lipids, dietary fat typically comes to mind. Yet a new study shows that dietary carbohydrate, specifically high-fructose corn syrup, can have a large impact on blood lipid markers of cardiovascular disease risk.IntroductionDietary fats have well-established impacts on blood lipids. For example, in short-term feeding trials, saturated fat tends to increase total cholesterol, increase LDL ("bad") cholesterol, and increase HDL ("good") cholesterol, while the omega-6 polyunsaturated fat linoleic acid...
What Properties Make a Food "Addictive"?
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Although the concept of food addiction remains controversial, there's no doubt that specific foods can provoke addiction-like behaviors in susceptible people. Yet not all foods have this effect, suggesting that it's related to specific food properties. A new study aims to identify the properties that make a food "addictive". IntroductionRead more...
Food Reward Friday
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This week's lucky winner... the Pizza Hut Hot Dog Bites pizza!!!Read more...
Insulin Resistance Predicts a Variety of Age-related Diseases
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In the last post, I reviewed a study by Gerald Reaven's group showing that insulin resistance strongly predicts the risk of cardiovascular disease over a 5-year period. In 2001, Reaven's group published an even more striking follow-up result from the same cohort (1). This study shows that not only does insulin resistance predict cardiovascular disease risk, it also predicts a variety of age-related diseases, including hypertension, coronary heart disease, stroke, cancer, type 2 diabetes, and even overall mortality risk.Read more...
Insulin Resistance Strongly Predicts Cardiovascular Disease Risk
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I recently came across a very interesting paper by the research team of Gerald Reaven, an endocrinologist at Stanford. He has long been one of the leading researchers studying insulin resistance, the metabolic syndrome, and their association with obesity. Reaven's research, and that of many others, suggests that insulin resistance is a central part of the constellation of metabolic disturbances that are so common in affluent nations*. We also have good reason to believe that it contributes to cardiovascular risk.All the way back in 1998, Reaven's group published a paper that should raise the eyebrows of anyone interested in cardiovascular health (1).Read more...
Food Reward Friday
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This week's lucky "winner"... Hardee's Most American Thickburger!!Read more...
Recent Interviews
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Here are two recent interviews I'd like to share with readers:Danny Lennon of Sigma NutritionDanny Lennon is an evidence-based nutrition coach who publishes a podcast called Sigma Nutriton Radio. We had a nice conversation about why we overeat, including energy homeostasis and the personal economics of food choice. The podcast has a high production value. You can listen to the interview here.Angelo Coppola of Latest in PaleoAngelo Coppola and I hit it off recently due to our mutual interests in gardening and self-reliance. We recently had a nice conversation about hunter-gatherer dietary patterns, the personal economics of food choice, US diet history, legumes and the Paleo diet, and how much meat we should eat. You...
New Study Strengthens the Case that LDL Causes Heart Disease
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There is little remaining doubt in the scientific/medical community that high levels of LDL, so-called "bad cholesterol", cause heart disease. Yet in some alternative health circles, the debate continues. A new study adds substantially to the evidence that LDL plays a causal role in heart disease.Read more...
Do Slower-digesting Carbohydrates Make Us Feel More Full?
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One of the most common pieces of advice in the health-nutrition world is that we should focus our carbohydrate intake on slowly-digesting carbohydrates, because they make us feel more full than rapidly-digesting carbohydrates. Rapidly-digesting carbohydrates, such as potatoes, stand accused of causing us to overeat, resulting in obesity, diabetes, and many other chronic ailments. Is this true?Read more...
My Buddy and Me
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Warning -- Satire -- April Fools PostI have a sheepish confession to make: until recently, I had a tapeworm, and that's why I'm lean.In 2006, I took a trip to Mexico with a few friends. We often traveled through rural areas, and of course sampled the local cuisine wherever we went. In many parts of Mexico, pork is an important food. Some of it may have been a bit undercooked.At the time, my interest in food and health was growing, and I was making many changes to my diet. I was glad to see the chubbiness around my neck and waist begin to disappear. The diet was working! Or so I thought...Read more...
Is Meat Unhealthy? Consolidated links
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Several people have asked for a consolidated list of links to my series on meat and health. Here it is! This should make it easier to share. Is Meat Unhealthy? Part I. Introduction and ethical/environmental considerations.Is Meat Unhealthy? Part II. Our evolutionary history with meat.Is Meat Unhealthy? Part III. Meat and cardiovascular disease.Is Meat Unhealthy? Part IV. Meat and obesity risk.Is Meat Unhealthy? Part V. Meat and type 2 diabetes risk.Is Meat Unhealthy? Part VI. Meat and cancer risk.Is Meat Unhealthy? Part VII. Meat and total mortality.Is Meat Unhealthy? Part VIII. Health vs. the absence of disease.Is Meat Unhealthy?...
Food Reward Friday
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This week's lucky "winner"... a bacon hot dog donut, by Krispy Kreme!Read more...
Food Reward Friday
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This week's lucky "winner"... donuts!!Krispy Kreme donuts being made. Hopefully this image isn't appetizing enough to make you want donuts.Read more...
Build Your Own Yogurt Maker, Sous-vide Cooker, and All-purpose Fermenter for $40
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I make a half gallon of yogurt, twice a month. I like making my own yogurt for many reasons, but it's a bit of a pain. Since I make large batches, I can't use a standard yogurt maker. I often get distracted and over-heat the milk, and the method I use to incubate the yogurt is wildly inefficient (my beloved Excalibur dehydrator). I also need a constant warm temperature for various other fermentation projects, and that's often difficult to achieve with the tools I have. I...
Is Meat Unhealthy? Part IX
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Welcome to the last post in the series. Time to summarize and wrap it up!RespectI respect each person's right to choose the diet they prefer. This includes vegetarians and vegans, particularly because most of them make daily sacrifices to try to make the world a better place for all of us. I'm an omnivore, but I sympathize with some of the philosophy and I often eat beans or lentils instead of meat*.Our history with meatOur ancestors have probably been eating some form of meat continuously for at least two hundred million years. However, the quantity has waxed and waned. The first mammals were probably largely carnivorous (insectivores). Yet our primate ancestors went through a 60-million-year arboreal phase,...
We Do Science Interview
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I recently did an interview with Laurent Bannock, an expert in sport and exercise nutrition. His podcast We Do Science has rapidly become quite popular, due to Laurent's credibility and the interesting guests he interviews. We covered body composition, metabolically healthy obesity, the relationship between BMI and mortality, calorie counting, body fat regulation, and other related topics.If you've already listened to several of my interviews and are starting to find them repetitive, you might enjoy this one because we cover some new ground. Laurent was a gracious host. Follow the link below to listen:Neurobiology of Obesity, with Stephan Guyen...
Food Reward Friday
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This week's lucky "winner"... the Cinnabon cinnamon roll!!!Read more...
Can High-Fiber Foods Fight the Metabolic Syndrome?
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The metabolic syndrome (MetSyn) is a cluster of signs including abdominal obesity, insulin resistance, high blood pressure, and blood lipid disturbances. MetSyn is the quintessential modern metabolic disorder, and it affects about one third of Americans. Many MetSyn diets recommend eating high-fiber foods, and research on the role of the gut microbiota in body weight and health tends to support this recommendation. Yet these diets are complex, so it's difficult to attribute positive effects to the high-fiber foods specifically, and some people have questioned the benefits of dietary fiber. Do high-fiber foods really improve MetSyn and promote weight loss?The studyRead more...
Is Meat Unhealthy? Part VIII
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Health can be defined as the absence of disease, and that is the lens through which we've been examining meat so far. However, most of us have a broader view of health that also includes optimal growth and development, physical and mental performance, well-being, fertility, immunity, robustness, and resilience. What role does meat play in this broader view of health?Non-industrial culturesOne of the things I keep coming back to in this series is the strong natural affinity that our species has for meat. Every culture that does not prohibit meat consumption for religious reasons (e.g., Indian Hindus) seeks and eats meat avidly. A key fact that stands out from my recent conversations with anthropologists is that hunter-gatherers...
Food Reward Friday
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This week's lucky "winner"... the KFC Double Down Dog!!Read more...
Is Meat Unhealthy? Part VII
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Looking at individual diseases is informative, but it can cause us to become myopic, making broad health-related decisions based on narrow information. It can cause us to miss the forest for the trees. In this case, the "trees" are individual diseases and the "forest" is total mortality: the overall risk of dying from any cause. Does eating meat increase total mortality, shortening our lifespans?Non-industrial culturesTraditionally-living cultures such as hunter-gatherers and non-industrial agriculturalists are not the best way to answer this question, because their mean lifespans tend to be short regardless of diet. This is due to ~30 percent infant mortality, which drags down the average, as well as a high risk of...
Does high protein explain the low-carb "metabolic advantage"?
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In 2012, David Ludwig's group published a paper that caused quite a stir in the diet-nutrition world (1). They reported that under strict metabolic ward conditions, weight-reduced people have a higher calorie expenditure when eating a very low carbohydrate diet (10% CHO) than when eating a high-carbohydrate diet (60% CHO)*. In other words, the group eating the low-carb diet burned more calories just sitting around, and the effect was substantial-- about 250 Calories per day. This is basically the equivalent of an hour of moderate-intensity exercise per day, as Dr. Ludwig noted in interviews (2). The observation is consistent with the claims of certain low-carbohydrate diet advocates that this dietary pattern confers a "metabolic...
Is Meat Unhealthy? Part VI
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In this post, I'll examine the possible relationship between meat consumption and cancer risk.Is cancer risk even modifiable?Cancer is caused by the uncontrolled division of a population of rogue cells in the body. These cells essentially evolve by natural selection to escape the body's multiple anti-cancer mechanisms. To a large extent, cancer appears to be a numbers game. The human body contains about 37 trillion cells. To get cancer, all you need is one cell that develops key mutations that allow it to shed its built-in restrictions on cell division. The older you are, the more time you have to accumulate mutations, explaining why cancer risk rises sharply with age.Unlike other common non-communicable diseases,...
