Friday, December 26, 2014

Tuesday, December 16, 2014

Is Meat Unhealthy? Part V

In this post, I'll examine the possible relationship between meat intake and type 2 diabetes.  Type 2 diabetes is the most common form of diabetes, and it is strongly linked to lifestyle factors.

Non-industrial cultures

Non-industrial cultures have an extremely low prevalence of diabetes, whether they are near-vegan or near-carnivorous.  This is supported by blood glucose measurements in a variety of cultures, from the sweet potato farmers of the New Guinea highlands to the arctic Inuit hunters.  Here is what Otto Schaefer, director of the Northern Medical Research Unit at Charles Camsell hospital in Edmonton, Canada, had to say about the Inuit in the excellent book Western Diseases (Trowell and Burkitt, 1981):
Read more »

Friday, December 5, 2014

Wednesday, December 3, 2014

Is Meat Unhealthy? Part IV

In this post, I'll address the question: does eating meat contribute to weight gain?

Non-industrial cultures

I'll get right to the point: humans living in a non-industrialized setting tend to be lean, regardless of how much meat they eat.  This applies equally to hunter-gatherers, herders, and farmers.

One of the leanest populations I've encountered in my reading is the 1960s Papua New Guinea highland farmers of Tukisenta.  They ate a nearly vegan diet composed almost exclusively of sweet potatoes, occasionally punctuated by feasts including large amounts of pork.  On average, they ate very little animal food.  Visiting researchers noted that the residents of Tukisenta were "muscular and mostly very lean", and did not gain fat with age (1, Western Diseases, Trowell and Burkitt, 1981).

!Kung man gathering mongongo fruit/nuts.
From The !Kung San, by Richard B. Lee.
Another remarkably lean hunter-gatherer population is the !Kung San foragers of the Kalahari desert.  The !Kung San are so lean that many of them would be considered underweight on the standard body mass index scale (BMI less than 18.5).  Average BMI doesn't exceed 20 in any age category (The !Kung San, Richard Lee, 1979).  Is this simply because they're starving?  It is true that they don't always get as much food as they'd like, but on most days, they have the ability to gather more food than they need.  The fact that they are able to reproduce normally suggests that they aren't starving.  Richard Lee's detailed work with the !Kung San indicates that approximately 40 percent of their calories came from animal foods during his study period in the 1960s.  This was mostly meat, with occasional eggs when available.

Read more »

Monday, December 1, 2014

Recent Interviews

For those who don't follow my Twitter account (@whsource), here are links to my two most recent interviews.

Smash the Fat with Sam Feltham.  We discuss the eternally controversial question, "is a calorie a calorie"?  Like many other advocates of the low-carbohydrate diet, Feltham believes that the metabolic effects of food (particularly on insulin), rather than calorie intake per se, are the primary determinants of body fatness.  I explain the perspective that my field of research has provided on this question.  We also discussed why some lean people become diabetic.  Feltham was a gracious host.

Nourish, Balance, Thrive with Christopher Kelly.  Kelly is also an advocate of the low-carbohydrate diet for fat loss.  This interview covered a lot of ground, including the insulin-obesity hypothesis, regulation of body fatness by the leptin-brain axis, how food reward works to increase calorie intake, and the impact of the food environment on food intake.  I explain why I think proponents of the insulin-obesity hypothesis have mistaken association for causation, and what I believe the true relationship is between insulin biology and obesity.  Kelly was also a gracious host.  He provides a transcript if you'd rather read the interview in text form.

Monday, November 24, 2014

Is Meat Unhealthy? Part III

When we consider the health impacts of eating meat, cardiovascular disease is the first thing that comes to mind.  Popular diet advocates often hold diametrically opposed views on the role of meat in cardiovascular disease.  Even among researchers and public health officials, opinions vary.  In this post, I'll do my best to sort through the literature and determine what the weight of the evidence suggests.

Ancel Keys and the Seven Countries Study

Ancel Keys was one of the first researchers to contribute substantially to the study of the link between diet and cardiovascular disease.  Sadly, there is a lot of low-quality information circulating about Ancel Keys and his research (1).  The truth is that Keys was a pioneering researcher who conducted some of the most impressive nutritional science of his time.  The military "K ration" was designed by Keys, much of what we know about the physiology of starvation comes from his detailed studies during World War II, and he was the original Mediterranean Diet researcher.  Science marches on, and not all discoveries are buttressed by additional research, but Keys' work was among the best of his day and must be taken seriously.

One of Keys' earliest contributions to the study of diet and cardiovascular disease appeared in an obscure 1953 paper titled "Atherosclerosis: A Problem in Newer Public Health" (2).  This paper is worth reading if you get a chance (freely available online if you poke around a bit).  He presents a number of different arguments and supporting data, most of which are widely accepted today, but one graph in particular has remained controversial.  This graph shows the association between total fat intake and heart disease mortality in six countries.  Keys collected the data from publicly available databases on global health and diet:


Read more »

Monday, October 27, 2014

Is Meat Unhealthy? Part II

In the last post, I said Part II would be about cardiovascular disease.  Shortly after publishing that, I realized that before we move on to diseases, we need to set the stage by considering our evolutionary history with meat.  So here we go.

Human Evolutionary History with Meat: 200 to 2.6 Million Years Ago

Mammals evolved from ancestral "mammal-like reptiles" (therapsids, then cynodonts) approximately 220 million years ago (Richard Klein. The Human Career. 2009).  Roughly 100 million years ago, placental mammals emerged.  The earliest placental mammals are thought to have been nocturnal shrew-like beasts that subsisted primarily on insects, similar to modern shrews and moles.  Mammalian teeth continued to show features specialized for insect consumption until the rise of the primates.

65 million years ago, coinciding with the evolution of the first fruiting plants, our ancestors took to the trees and became primates.  For most of the time between then and now, our ancestors likely ate the prototypical primate diet of fruit, seeds, leaves/stems, and insects (1).  Some primates also hunt smaller animals and thus eat the flesh of mammals, birds, reptiles, amphibians, and fish in addition to insects.  However, the contribution of non-insect meat to the diet is usually small.

Read more »

Friday, October 24, 2014

Tuesday, October 21, 2014

Is Meat Unhealthy? Part I

Introduction

At Dr. McDougall's Advanced Study Weekend, I had the opportunity to hear a number of researchers and advocates make the case for a "plant-based diet", which is a diet containing little or no animal foods.  Many of them voiced the opinion that animal foods contribute substantially to the primary killers in the US, such as heart disease and cancer.  Some of the evidence they presented was provocative and compelling, so it stimulated me to take a deeper look and come to my own conclusions.

No matter what the health implications of meat eating turn out to be, I respect vegetarians and vegans.  Most of them are conscientious, responsible people who make daily personal sacrifices to try to make the world a better place for all of us.

My Experience with Vegetarian and Vegan Diets

Read more »

Tuesday, October 14, 2014

Obesity → Diabetes

A new study adds to the evidence that the prevalence of type 2 diabetes is rapidly increasing in the US, and our national weight problem is largely to blame.

The Centers for Disease Control (CDC) currently estimates that a jaw-dropping 33 percent of US men, and 39 percent of US women, will develop diabetes at some point in their lives (1).  Roughly one out of three people in this country will develop diabetes, and those who don't manage it effectively will suffer debilitating health consequences.  Has the risk of developing diabetes always been so high, and if not, why is it increasing?

In the same issue of the Annals of Internal Medicine as the low-carb vs. low-fat study, appears another study that aims to partially address this question (2).

Read more »

Wednesday, October 1, 2014

Metabolic Effects of a Traditional Asian High-carbohydrate Diet

A recent study supports the notion that an 'ancestral diet' focused around high-starch agricultural foods can cultivate leanness and metabolic health.

John McDougall gave Christopher Gardner a hard time at the McDougall Advanced Study Weekend.  Dr. Gardner conducts high-profile randomized controlled trials (RCTs) at Stanford to compare the effectiveness of a variety of diets for weight loss, cardiovascular and metabolic health.  The "A to Z Study", in which Atkins, Zone, Ornish, and LEARN diets were pitted against one another for one year, is one of his best-known trials (1).

Dr. McDougall asked a simple question: why haven't these trials evaluated the diet that has sustained the large majority of the world's population for the last several thousand years?  This is an agriculturalist or horticulturalist diet based around starchy foods such as grains, tubers, legumes, and plantains, and containing little fat or animal foods.  Researchers have studied a number of cultures eating this way, and have usually found them to be lean, with good cardiovascular and metabolic health.  Why not devote resources to studying this time-tested ancestral diet?  I think it's a fair question.

Read more »

Friday, September 26, 2014

Help Advance Diabetes Research

A University of Virginia researcher named Hannah Menefee contacted me recently to ask for our help.  She and her colleagues are conducting a study on how people with type 2 diabetes use Facebook to manage their health, and how that technology can be leveraged to support effective health communication.

If you have type 2 diabetes, and you'd like to participate in the study, please join their Diabetes Management Study Facebook group.  There, you'll receive more information about the study, you'll receive a short survey, and you may be invited into one of the study phases.

Thursday, September 18, 2014

My AHS14 Talk on Leptin Resistance is Posted

The Ancestral Health Society just posted a video of my recent talk "What Causes Leptin Resistance?"  Follow the link below to access it.  Enjoy!

What Causes Leptin Resistance?


Monday, September 8, 2014

Thoughts on the McDougall Advanced Study Weekend

For those of you who aren't familiar with him, Dr. John McDougall is a doctor and diet/health advocate who recommends a very low fat, high starch, whole food vegan diet to control weight and avoid chronic disease.  He's been at it for a long time, and he's a major figure in the "plant-based diet" community (i.e., a diet including little or no animal foods).

Dr. McDougall invited me to participate in his 3-day Advanced Study Weekend retreat in Santa Rosa, CA.  My job was to give my talk on insulin and obesity, and participate in a panel discussion/debate with Dr. McDougall in which we sorted through issues related to low-carb, Paleo, and the health implications of eating animal foods.  I was glad to receive the invitation, because I don't see myself as a diet partisan, and I believe that my evidence-based information is applicable to a variety of diet styles.  I saw the Weekend as an opportunity to extend my thoughts to a new community, challenge myself, and maybe even learn a thing or two.  It was particularly interesting to compare and contrast the Advanced Study Weekend with the Ancestral Health Symposium, which is more Paleo- and low-carb-friendly.

General Observations

The attendees were a lot older than AHS attendees.  I estimate that most of them were in their 60s, although there were some young people in attendance.

I don't place too much emphasis on peoples' personal appearance at conferences like this.  You don't know what a person's background, genetics, or personal struggles may be, you don't know how closely they adhere to the program, and you don't know to what degree a group of people might be self-selected for particular traits*.  But I will note that Dr. McDougall, his family, and many of the other starch-based/plant-based diet advocates tended to be extremely lean with low fat and muscle mass.  They also tended to have a healthy and energetic appearance and demeanor.  As I would expect, decades of exceptionally high starch intake hasn't made them obese or obviously ill.

Read more »

Thursday, September 4, 2014

What about the Other Weight Loss Diet Study??

The same day the low-fat vs low-carb study by Bazzano and colleagues was published, the Journal of the American Medical Association published a meta-analysis that compared the effectiveness of "named diet programs".  Many people have interpreted this study as demonstrating that low-carbohydrate and low-fat diets are both effective for weight loss, and that we simply need to pick a diet and stick with it, but that's not really what the study showed.  Let's take a closer look.

Johnston and colleagues sifted through PubMed for studies that evaluated "named diet programs", such as Ornish, Atkins, LEARN, Weight Watchers, etc (1).  In addition, the methods state that they included any study as low-carbohydrate that recommended less than 40% of calories from carbohydrate, was funded by the Atkins foundation, or was "Atkins-like".  These criteria weren't extended to the low-fat diet: only studies of name-brand low-fat diets like the Ornish diet were included, while the meta-analysis excluded low-fat diet studies whose guidelines were based on recommendations from government and academic sources, even though the latter group represents the majority of the evidence we have for low-fat diets.  The inclusion criteria were therefore extremely asymmetrical in how they represented low-carb and low-fat diets.  This fact explains the unusual findings of the paper.

The abstract immediately activated my skeptic alarm, because it states that at the one-year mark, low-carbohydrate diets and low-fat diets both led to a sustained weight loss of about 16 pounds (7.3 kg).  Based on my understanding of the weight loss literature, that number seems far too high for the low-fat diet, and also too high for the low-carbohydrate diet.

Read more »

Monday, September 1, 2014

Low-carbohydrate vs. Low-fat diets for Weight Loss: New Evidence

A new high-profile study compared the weight loss and cardiovascular effects of a low-carbohydrate diet vs. a low-fat diet.  Although many studies have done this before, this one is novel enough to add to our current understanding of diet and health.  Unlike most other studies of this nature, diet adherence was fairly good, and carbohydrate restriction produced greater weight loss and cardiovascular risk factor improvements than fat restriction at the one-year mark.  Yet like previous studies, neither diet produced very impressive results.

The Study

Lydia A. Bazzano and colleagues at Tulane University randomly assigned 148 obese men and women without cardiovascular disease into two groups (1):
  1. Received instructions to eat less than 40 grams of carbohydrate per day, plus one low-carbohydrate meal replacement per day.  No specific advice to alter calorie intake.  Met regularly with dietitians to explain the dietary changes and maintain motivation.
  2. Received instructions to eat less than 30 percent of calories from fat, less than 7 percent of calories as saturated fat, and 55 percent of calories from carbohydrate, plus one low-fat meal replacement per day.  No specific advice to alter calorie intake.  This is based on NCEP guidelines, which are actually designed for cardiovascular risk reduction and not weight loss.  Met regularly with dietitians to explain the dietary changes and maintain motivation.
Participants were followed up for one year, with data reported for 3 month, 6 month, and 12 month timepoints.  This study actually measured body fat percentage, but unfortunately did so using bioelectrical impedance (like on some bathroom scales), which is essentially meaningless in this context.

Results

Read more »

Monday, August 18, 2014

Science of Nutrition Podcast

I recently did an interview with Seth Yoder, who has a master's degree in nutrition science and writes the blog The Science of Nutrition.  Seth caught my attention recently with his withering review of The Big Fat Surprise, the latest book to claim that ideological/incompetent scientists and public policy makers got the science of nutrition backward and we should all be eating low-carb, high-fat, high-meat diets.  I was impressed by how deeply Seth dug into the reference list, and how well he picked up on subtle but troubling misrepresentations of the evidence.

Last week, Seth and I got together at a local brewpub to do an interview.  We were joined by Carrie Dennett, an MPH/RDN who has a nutrition blog and writes for the Seattle Times.  I'd probably do a lot more interviews if I could ride my bike to them and have my interviewer buy me a drink.

Speaking of drinks, by the end of the interview I had a little buzz-- you might hear it in my voice if you listen closely.  As usual, I had plenty to say about body fat regulation, food reward, and other topics, with plenty of side trips to discuss particularly fascinating studies.  Also, the word of the day was 'compelling'.

Enjoy the interview!

Tuesday, August 5, 2014

Can Hypothalamic Inflammation and Leptin Resistance be Reversed?

A new study by yours truly begins to address the key question: can hypothalamic inflammation and leptin resistance be reversed?

Leptin is the primary hormonal regulator of body fatness in the human body (1).  Secreted by fat tissue, it acts in many places in the body, but its most important effects on body weight occur via the brain, and particularly a brain region called the hypothalamus.  The hypothalamus is responsible for keeping certain physiological variables within the optimal range, including blood pressure, body temperature, and body fatness.

In obesity, the brain loses its sensitivity to leptin, and this causes the body to begin 'defending' a higher level of body fatness, analogous to how a person with a fever 'defends' a higher body temperature (1).  Once a person has become obese, it's difficult to return to true leanness because this system vigorously opposes major fat loss.  Leptin resistance makes fat loss more difficult.

In rodent models, leptin resistance is caused at least in part by inflammatory signaling in the hypothalamus.  We can observe this in multiple ways, but one common way is to look at the appearance of specific cells in the brain that change number, size, and shape when inflammation is present (2).  These cells are called microglia and astrocytes.  In addition to the work in rodents, we've published preliminary evidence that these same inflammatory changes occur in the hypothalamus of obese humans (2).

A key question is whether or not these inflammatory changes can be reversed.  Is a person with leptin resistance doomed to have it forever, undermining fat loss efforts for the rest of his or her life?  Or can it be corrected, possibly allowing easier and more sustainable fat loss?  We just published a study in Endocrinology that begins to answer this question, using a mouse model of dietary obesity (3).  I'm co-first author of this study along with my colleague Kathryn Berkseth, MD.  My former mentor Mike Schwartz, MD is senior author.

The Study

Read more »

Friday, August 1, 2014

Wednesday, July 23, 2014

Help Fund High-Quality Research on Diet and Health

University of California, San Francisco researcher Dr. Ashley Mason has asked me to spread the word about a diet-health study she's preparing to conduct in collaboration with Dr. Lynda Frassetto.  Dr. Frassetto is a widely recognized expert on mineral metabolism and bone health, and also one of the few researchers who has managed to wrangle funding to study the health impacts of a Paleolithic-style diet.  Her findings have been quite provocative.  

Together with their collaborators, Drs. Mason and Frassetto are preparing another diet-health trial to study the impact of two different diets on polycystic ovary syndrome, or PCOS.  PCOS is a common hormonal disorder among reproductive-age women, and its signs and symptoms include ovarian cysts, excess hair growth, menstrual irregularity or absence, infertility, and obesity.  Its causes are unknown, but insulin resistance is a core characteristic of it and is thought to play an important role.  PCOS is thought to be influenced by diet and lifestyle. 


A research team including Drs. Frassetto and Mason, as well as Drs. Umesh Masharani, Heather Huddleston, and Michael Cohn will test a Paleolithic-style diet and an American Diabetes Asssociation diet to see if either or both improves insulin resistance and menstrual cycle regularity for women with PCOS.  Each diet will likely have beneficial effects, however it remains unknown which will be more effective at treating PCOS.

Currently, it's exceedingly difficult for researchers to land funding from the National Institutes of Health (NIH) to do nutrition-related research in the context of disease treatment or management, particularly if it involves a Paleo diet. Recognizing the important potential of fleshing out the relationship between diet and health, researchers are looking for other ways to fund their work.  This study will give them the early data they need to start large, truly definitive studies of the links between diet and insulin resistance, and you can help make it happen.

Please check out their crowdfunding website to learn more about the study, the researchers, and make tax-deductible donations to support their work. And, if you're attending the Ancestral Health Symposium, one of the "backer" rewards is having lunch with the researchers.

Click here to see their crowdfunding site! 



This post was prepared in part using content provided by Dr. Mason.

Monday, July 14, 2014

Instant Pot Electronic Pressure Cooker: Two Years Later

I've had several people tell me that the Whole Health Source post that changed their lives the most was one I published in 2015-- about a pressure cooker.

In 2015, I first reviewed the Instant Pot-- a "pressure cooker for the 21st century" that also doubles as a slow cooker and rice cooker (1).  Since then, we've used it more than 400 times, and it has saved us countless hours of kitchen drudgery.  It's indispensable for my current cooking style, and a major time saver for anyone who leads a busy life but still wants to cook wholesome food at home.  It's extremely satisfying to be able to put your ingredients into the Instant Pot, push a couple of buttons, do something else until it beeps, and then eat a healthy, inexpensive, and delicious meal.

Pressure cookers are one of the most time- and energy-efficient cooking tools, but electronic versions are even more efficient than traditional stovetop pressure cookers.  They're more time-efficient because you don't have to fiddle with them-- for example, adjusting the heat.  They're more energy-efficient because 1) they stop heating when the interior has reached the appropriate pressure, meaning that they're only using energy for part of the cooking process and they hardly vent any energy-wasting steam, and 2) they're insulated well enough that the sides never get hot.

I've used my Instant Pot for a wide variety of cooking tasks, and this is what it does best:

Read more »

Thursday, July 10, 2014

Upcoming Talks

I have two talks planned over the next two months.  Hope to see you there!

Ancestral Health Symposium 2014: UC Berkeley, August 7-9

If you want to understand the most rigorous science available on leptin resistance-- a key mechanism of obesity and a major barrier to fat loss-- this talk is for you.  This is my primary area of professional expertise; I have years of firsthand research experience on the subject and I've published a number of related papers in peer-reviewed journals.  The talk will be accessible to nearly all levels of expertise.  AHS14 tickets are available here.  I've pasted the talk's abstract below.

What Causes Leptin Resistance?

Leptin is the primary hormonal regulator of body fatness.  Obese people exhibit a resistance to leptin’s effects in the brain, causing the brain to oppose fat loss by multiple mechanisms.  Research in animal models suggests that leptin resistance may be required for obesity to develop.  How does leptin resistance occur, and what causes it?  Research has not yet provided us with definitive answers, but several plausible possibilities have emerged.  This talk will review what is known about leptin resistance and its causes.

McDougall Advanced Study Weekend: Santa Rosa, CA, September 5-7

Dr. John McDougall invited me to speak at his yearly symposium after viewing my TEDx talk "The American Diet: a Historical Perspective".  I look forward to sharing my thoughts and interacting with a different audience than I'm used to.  The talk will be an expanded version of the one I presented at AHS13.  Tickets are available here.  I've pasted a modified version of my AHS13 abstract below.

Insulin and Obesity: Reconciling Conflicting Evidence

The pancreatic hormone insulin regulates the trafficking and metabolism of carbohydrate and fat, and its secretion is particularly stimulated by carbohydrate and protein.  Since circulating insulin is elevated in common obesity, and insulin influences fatty acid flux into and out of fat tissue, this has raised the possibility that elevated insulin causes common obesity, and that dietary carbohydrate is particularly fattening.  A large amount of evidence appears to support the hypothesis that insulin causes obesity, and a large amount of evidence appears to falsify it.  This presentation will outline a framework capable of reconciling this seemingly conflicting evidence.

Wednesday, June 25, 2014

Fat and Carbohydrate: Clarifications and Details

The last two posts on fat and carbohydrate were written to answer a few important, but relatively narrow, questions that I feel are particularly pertinent at the moment:
  • Was the US obesity epidemic caused by an increase in calorie intake?
  • Could it have been caused by an increase in carbohydrate intake, independent of the increase in calorie intake?
  • Does an unrestricted high-carbohydrate diet lead to a higher calorie intake and body fatness than an unrestricted high-fat diet, or vice versa?
  • Could the US government's advice to eat a low-fat diet have caused the obesity epidemic by causing a dietary shift toward carbohydrate?
However, those posts left a few loose ends that I'd like to tie up in this post.  Here, I'll lay out my opinions on the relationship between macronutrient intake and obesity in more detail.  I'll give my opinions on the following questions:
  • What dietary macronutrient composition is the least likely to cause obesity over a lifetime?
  • What dietary macronutrient composition is best for a person who is already overweight or obese?
  • Is fat inherently fattening and/or unhealthy?
From the beginning

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Cherry blossoms - Flores de cerezo - Fotografías bonitas

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type='html'>Cherry blossoms - Flores de cerezo - Fotografías bonitas
Imagen: Sborisov / 123RF Stock Photo

Sunday, June 22, 2014

Dos gorilas bailando mientras su mamá los observa detenidamente (Fotos de Animales Graciosos)

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type='html'>Frase del momento:"Los amigos son como los zapatos. Podemos tener muchos, pero siempre andamos con los que nos sentimos más a gusto."
Imagen: enjoylife25 / 123RF Foto de archivo

Wednesday, June 18, 2014

Regalos de navidad en forma de estrella

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Regalos de Navidad
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Nota: Haga usted click aquí para ver más imágenes para navidad

Wednesday, June 11, 2014

Has Obesity Research Failed?

I frequently encounter the argument that obesity research has failed because it hasn't stopped the global increase in obesity rates.  According to this argument, we need to re-think our approach to obesity research because the current approach just isn't working.

Grant funding for obesity research keeps increasing in the US, and the prevalence of obesity also keeps increasing*.  What gives?  Maybe if we just scrapped the whole endeavor we'd be better off.

Let's take a closer look at this argument and see how it holds up.

Why Do Research?

There are two fundamental reasons why we do research:
  1. To gather accurate information about the natural world.  This information is intrinsically valuable because we like knowing how the world works, and it may eventually have practical value that's not immediately obvious.
  2. Practical applications.  We want to solve problems and improve our lives.
If we want to determine whether or not obesity research has failed, we should evaluate it using those two metrics.

Has Obesity Research Gathered Accurate Information?

Read more »

Tuesday, June 10, 2014

Las nuevas plantillas personalizadas de Gmail, le permiten a usted poner su propia imagen de fondo.

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type='html'>Las nuevas plantillas personalizadas de Gmail, le permiten a usted poner su propia imagen de fondo.Para quienes como yo usan Gmail como cliente de correo electrónico, les informo que las nuevas plantillas personalizadas, incluyen la opción de poner como fondo la imagen de su preferencia. Así que a partir de ahora, usted podrá darle un uso más a las miles de imágenes gratis que tenemos para usted. Si usted aún no tiene una cuenta de Gmail, puede abrirla haciendo click aquí.

Wednesday, June 4, 2014

¡Que tengas un excelente INICIO DE SEMANA!

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type='html'>¡Que tengas un excelente INICIO DE SEMANA!

Calorie Intake and Body Fatness on Unrestricted High-fat vs. High-carbohydrate Diets

In recent posts, we've explored the association between calorie intake and the US obesity epidemic, and the reasons why this association almost certainly represents a cause-and-effect relationship.  I also reviewed the evidence suggesting that carbohydrate and fat are equally fattening in humans, calorie for calorie.

One valid objection that came up in the comments is that calorie-controlled diets in a research setting may not reflect what happens in real life.  For example, in a context where calorie intake isn't tightly controlled, diet composition can impact calorie intake, in turn affecting body fatness.  This, of course, is true, and it forms one of the central pillars of our fat loss program the Ideal Weight Program.

Some low-carbohydrate diet advocates argue that the obesity epidemic was caused by US dietary guidelines that emphasize a carbohydrate-rich diet*.  The idea here is that the increase in calorie intake was due to the diet shifting in a more carbohydrate-heavy direction.  In other words, they're hypothesizing that a carbohydrate-rich eating style increases food intake, which increases body fatness**.  According to this hypothesis, if we had received advice to eat a fat-rich diet instead, we wouldn't be in the midst of an obesity epidemic.

Fortunately for us, this hypothesis has been tested-- many times!  Which eating style leads to higher calorie intake and body fatness when calories aren't controlled: a carbohydrate-rich diet, or a fat-rich diet?

Short-term Studies

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Friday, May 30, 2014

Thursday, May 29, 2014

Un lindo gatito jugando en el jardín - Little kitten playing

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type='html'>Un lindo gatito jugando en el jardín - Little kitten playingFrase del momento: Comenzemos a borrar viejos recuerdos, para darle oportunidad a nuevas experiencias. -Anónimo.

Wednesday, May 28, 2014

Chica con un arbol de navidad blanco

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Arboles de Navidad
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Saturday, May 24, 2014

Tren pasando por un puente muy alto en Wiesen, Suiza.

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type='html'>Tren pasando por un puente muy alto en Suiza¡A reir se ha dicho! -Mi vida, desde que te conocí no tomo, no fumo, ni apuesto en los casinos - ¿Tan buena influencia soy para ti? -No, es que ya no me alcanza el dinero, babosa. jajajajajajajaja -Foto: Syaochka

Wednesday, May 21, 2014

El Banco de Imágenes Gratis presenta: "La semana de los Animales" (Más de 100 fotos para compartir)

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type='html'>Animales presenta rinoceronte de africa en la sabanaY para empezar la semana dedicada a los animales de nuestro planeta, compartimos con usted esta bonita postal de un enorme rinoceronte en la sabana de África. Continuamos... -Foto: Pierivb

A New Understanding of an Old "Obesity Gene"

As you know if you've been following this blog for a while, obesity risk has a strong genetic component.  Genome-wide association studies (GWAS) attempt to identify the specific locations of genetic differences (single-nucleotide polymorphisms or SNPs) that are associated with a particular trait.  In the case of obesity, GWAS studies have had limited success in identifying obesity-associated genes.  However, one cluster of SNPs consistently show up at the top of the list in these studies: those that are near the gene FTO.

As with many of the genes in our genome, different people carry different versions of FTO.  People with two copies of the "fat" version of the FTO SNPs average about 7 pounds (3 kg) heavier than people with two copies of the "thin" version, and they also tend to eat more calories (1, 2).  

Despite being the most consistent hit in these genetic studies, FTO has remained a mystery.  As with most obesity-associated genes, it's expressed in the brain and it seems to respond somewhat to nutritional status.  Yet its function is difficult to reconcile with a role in weight regulation: 
  • It's an enzyme that removes methyl groups from RNA, which doesn't immediately suggest a weight-specific function.
  • It's not primarily expressed in the brain or in body fat, but in all tissues.
  • Most importantly, as far as we know, the different versions of the gene do not result in different tissue levels of FTO, or different activity of the FTO enzyme, so it's hard to understand how they would impact anything at all.  
An important thing to keep in mind is that GWAS studies don't usually pinpoint specific genes.  Typically, they tell us that obesity risk is associated with variability in a particular region of the genome.  If the region corresponds to the location of a single gene, it's a pretty good guess that the gene is the culprit.  However, that's not always the case...

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Sunday, May 18, 2014

Hermosa rosa sobre una plataforma de color blanco

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Rosa Roja
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Nota: Haga usted click aquí para ver más Flores de colores

Thursday, May 15, 2014

Manual de Técnica Fotográfica - Desde lo más básico, hasta los más grandes secretos de la fotografía digital.

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Desde hace 7 años, el Banco de Imágenes Gratis .Com, ha compartido con usted miles de fotos sobre diversas categorías. Imágenes fascinantes que muchas veces quien las recibe, se pregunta cómo hacen los fotógrafos asociados a nuestro proyecto para tomar esas bellísimas fotografías.

En la actualidad, son cada vez más las personas que tienen acceso a una cámara digital compacta, semi profesional o profesional. Sin embargo, tener una cámara no es suficiente para capturar de la mejor manera ese momento tan especial e inmortalizarlo para siempre.

Como todo, requiere preparación, teoría y práctica. Es por eso, que el día de hoy deseo recomendarles un excelente libro titulado "Manual de Técnica Fotográfica" escrito por el reconocido fotógrafo profesional Juan Ignacio Torres.

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Manual de Técnica Fotográfica de Juan Ignacio Torres
Lo más curioso de todo, es que en la compra de este libro que sólo cuesta $19 dólares, usted obtendrá tres libros más totalmente gratis con los siguientes títulos. Iluminación Fotográfica, Retrato Fotográfico y Los 5 Errores Más Comunes en la Fotografía Digital.
Libros gratis en la compra de Manual de Tecnica Fotografica de Juan Ignacio Torres
Esta promoción, es válida para todos los usuarios de nuestra página, fans en facebook, seguidores en twitter, amigos de Google+ y contactos de todos ellos.

No olvide que para obtener más información de este libro deberá visitar el siguiente enlace. http://curso.maquinafotograficapro.com/ Gracias.

Wednesday, May 14, 2014

El Rey León paseando con sus dos hermosas leoncitas

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type='html'>El Rey León paseando con sus dos hermosas leoncitasA reir se ha dicho! -Suegra usted hizo muy hermosa a su hija y le voy a dar un regalo –Gracias, ¿Qué regalo me vas a dar? -Un nieto. jajajajajajajaja

Monday, May 12, 2014

Saturday, May 10, 2014

Pequeña cascada muy cerca de la playa - Little cascade

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type='html'>Pequeña cascada muy cerca de la playa - Little cascade - Wallpapers¡A reir se ha dicho! -Pepito, ¿por qué escribes calor con acento?
-Profe, usted dijo que el calor se acentúa en esta época del año! jajajajajajajaja