Thursday, July 29, 2010

Truth and Consequences

When I began losing weight with low-carb, my motivation was not the usual one. I knew that as an obese woman, I would have very little credibility as a scientist.

That sounds odd, doesn’t it? Why would obesity trump publications and other achievements in the professional world?

This week I came across an article in the journal Obesity, “The Stigma of Obesity: A Review and Update.” The authors, Rebecca Puhl and Chelsea Heuer, give numerous examples from the literature demonstrating that obese individuals are indeed the subjects of discrimination in many areas of life.

In the area of employment discrimination, the article states,

    One study (N = 2,838) found that overweight respondents were 12 times more likely, obese respondents were 37 times more likely, and severely obese respondents were 100 times more likely than normal-weight respondents to report employment discrimination. In addition, women were 16 times more likely to report weight-related employment discrimination than men.
This discrimination took the form of derogatory humor, pejorative comments, lower pay, denial of promotions and firing.

Weight bias is also seen in health care settings. Physicans, medical students, nurses and dieticians all expressed negative attitudes toward obese patients. Common adjectives were “lazy,” “lacking self control” and “noncompliant.” Medical students reported that severely obese patients were most frequently the target of derogatory humor among attending physicians, residents and students, especially in surgical specialties. Obese women, in particular, pick up on these attitudes. The article discusses several studies indicating that women in the United States are more likely to delay or forego preventive care as their BMI increases.

The article also addresses obesity and interpersonal relationships, including sexual relationships. One study asked 449 college students to rate six pictures of hypothetical sex partners in order of preference. The top ranking went to a healthy partner. Second was an armless partner. Third was a partner with a history of STDs. Fourth was a partner with mental illness. Fifth was a partner in a wheelchair. And sixth? You guessed it. Sixth was an obese partner. Not only that, although both men and women ranked the obese potential partner to be least desirable, the men ranked obese female partners significantly lower than the women ranked obese male partners.

Is this fair? No, it isn’t. Nevertheless, as the authors go on to describe weight bias in the media, it seems that weight bias, and particularly weight bias against women is pervasive. They conclude their article by discussing research to decrease biases against obesity and even legislation to prohibit weight discrimination.

While both of these approaches might be helpful in the long-term, for whatever reason there seems to be an intrinsic stigma against obesity. If you doubt that you have it, take a look at the picture at the top of this post and be honest about your responses. Because of this stigma, and because we all live in the real world, it seems that low-carbers have yet another reason to achieve and maintain a weight loss. Not only is a normal weight more healthy, a normal weight will give us a better chance at achieving our maximum potential in employment, in receiving health care and in forming interpersonal relationships.

Saturday, July 24, 2010

Thoughts on the China Study

There are about 2000 counties in China. In the 1980’s, Cornell University did a large ecological study in 65 of them and published the data as something called the China Study. The study measured 367 variables in about 6500 adults. It captured data on diet, lifestyle and disease and included analyses of blood and urine samples. The individual results were grouped geographically, by county, producing a data set with 65 (or fewer) observations for each variable that was measured.

T. Colin Campbell, Ph.D. was a researcher in this study. In 2005 he published a book, The China Study: Startling Implications for Diet, Weight Loss, and Long-Term Health, using data collected from the China Study, from his own published research and from several other sources. When all of this information was considered together, on page 7 of the 2004 edition of the book Dr. Campbell concluded that,

    People who ate the most animal-based foods got the most chronic disease. Even relatively small intakes of animal-based food were associated with adverse effects. People who ate the most plant-based foods were the healthiest and tended to avoid chronic disease.

In light of what low-carbers know personally and know from the scientific literature about the benefits of eating animal-based foods, Dr. Campbell’s conclusion is quite surprising. Vegans and vegetarians commonly use The China Study as proof that their food choices are scientifically superior to those that incorporate animal products. (Take a look at the comments on for just a few examples.) What’s a low-carber to think?

In 2005 Chris Masterjohn wrote a critique of The China Study. Masterjohn pointed out that the data showed that intake of animal protein did not correlate with mortality for all cancers. Although Campbell had tried to connect animal protein intake to cancer mortality through a set of six biomarkers like plasma copper and urea nitrogen, the relationships between animal protein intake, the biomarkers and the eventual deaths from cancer were poorly documented. Masterjohn also showed that Campbell had taken his own research on the tumor-promoting activity of casein in cancer-prone rats to make the astounding statement on page 104 of the book that “casein, and very likely all animal proteins, may be the most relevant cancer-causing substances that we consume.” This seems to be a bit of a logical stretch.

The discussion lay more-or-less dormant until 2010 when Denise Minger, a 23 year old English major and self-described data junkie, happened upon the raw China Study data and wrote a lengthy description of her criticisms of the book. In a 2001 symposium Dr. Campbell had summed up some of the findings of the China Study and a subsequent China Study II. He said, “Plasma cholesterol in the 90-170 milligrams per deciliter range is positively associated with most cancer mortality rates. Plasma cholesterol is positively associated with animal protein intake and inversely associated with plant protein intake.” After spending 1 ½ months of working with the raw data from the China Study, Ms. Minger found that the data in fact showed no statistically significant relationship between the intake of animal protein and cancer. (It also showed no statistically significant relationship between the intake of plant protein and cancer.)

So, how could Dr. Campbell describe a positive correlation between increased intake of animal protein and cholesterol and between increased cholesterol and cancer, while the raw data showed that there was no one-to-one relationship between intake of animal protein and cancer? The answer: confounding factors. Schistosomiasis is a common disease in China. It is caused by a worm not normally found in plant-based food nor in animal-based food but in contaminated water. Ms. Minger found that as schistosomiasis increases, plasma cholesterol increases significantly. (This may be the result of negative effects of schistosomiasis on normal liver function.) As schistosomiasis increases, the rate of colorectal cancer also increases significantly.

In other words, in counties where schistosomiasis was present, one would expect that people who had high cholesterol would also tend to have more colorectal cancer. Hence the presumed relationship between high cholesterol and cancer mortality in China would actually reflect a factor that had nothing to do with diet. And when Chinese counties with zero schistosomiasis infection are compared with respect to the relationship between total cholesterol and the rate of mortality from colorectal cancer, the correlation between the two variables disappears. In other words, Dr. Campbell’s reasoning that eating animal protein is associated with high cholesterol is in turn associated with increased cancer mortality is invalid. The data was presented in a way that it implied a relationship, but the relationship disappears with a more detailed analysis.

From there, Ms. Minger went on to dismantle one after another of Dr. Campbell’s assertions regarding the use of animal-based foods and damage to health. Other laypeople with statistical experience (here and here) also did their own data analysis and reinforced her conclusions.

Dr. Campbell responded to Ms. Minger’s criticisms here. His main objections seemed to be that she used adjectives (!), that she used univariate correlations (so did he) and that she was probably unable to have made her analyses without outside help.

Ms. Minger’s very detailed response to Dr. Campbell is here.

If you have time to read all of these links, they provide fascinating insight into the analysis and potential applications of an important ecological study. If you don’t, the bottom line is this: when you encounter a scientific study that seems to contradict everything you know about a particular subject, be sure to take a very careful look at the data to see if it might have been cherry-picked, over-interpreted, or analyzed without reference to potential confounding factors. If anything like this has happened, the conclusions of the investigators may not necessarily reflect what the data actually shows.

Thursday, July 15, 2010

Managing Hunger

(Warning: Most of my posts are science-based, but this one comes from my own experiences, i.e., n=1. Forewarned is forearmed, so here we go.)

One of the things I noticed before I began low-carbing was that after I ate a meal, I could only go a couple of hours before I had to have a snack. Hunger would overwhelm me, and since my willpower isn't great, I would give in. Eventually I became fat and prediabetic.

Then came low-carb. I could eat and leave the table satisfied. I could eat only at meals and not feel ravenously hungry between times. But as the years went by, I noticed that my between-meal hunger started to return. It wasn't as bad as before, but my willpower hadn't improved any and I would start snacking to the point that I was eating mass quantities of low-carb food almost every day. I found Dr. Atkins' Accel diet pills, and those seemed to help. Until the Atkins company quit making them. Next, somebody introduced me to the original formulation of Leptopril and that kept the hungries at bay fairly well. Until they changed the formula. Finally, the Country Life Diet Power pills seemed to help a bit, but eventually those became unavailable, too. And after that, I couldn't find another over-the-counter diet pill that worked for me.

In the world of weight loss and weight maintenace, calories don't count as much as carbs, but they do count. My weight was increasing slowly but surely and there seemed to be nothing I could do about it. I tried drinking lots of water. I tried different kinds of fiber. I tried zero-carb. I made charts of the ingredients of the diet pills that had worked to curb my hunger, and I couldn't figure out what the magic combination was.

When the between-meal hunger hit, I would look at the extra ten pounds of fat I was carrying and wonder--why, if I'm eating very low carb and if I have this stored fat available--why can't my body switch over and use some of that stored fat for energy?

A couple of weeks ago, when the hunger monster attacked about two hours after breakfast, for some reason I went to the kitchen and made a cup of regular coffee. No artificial sweetener and no whitener. Just black instant coffee in a cup. I sipped some of the coffee, put the cup on my desk and went back to work. The hunger abated for an hour or so, but then it returned. I sipped some more of the black coffee and the hunger went away again. I had lunch as usual, but sure enough, about two hours later the hunger monster came knocking. Again I sipped some coffee and it went away. I repeated this until dinner. After dinner I knew I couldn't drink caffeine or I wouldn't sleep, so I sipped on a diet soda instead and that seemed to work. I had eaten a reasonable amount of food at my three meals, and I didn't wake up hungry during the night.

The second day was easier. I knew that if the hunger monster hit, I would be able to switch my body into fat-burning mode by sipping the coffee. It worked, and it has worked ever since.

It's important to state that each day I have had a shake for breakfast, fatty meat, cheese and a few veggies for lunch and fatty meat, cheese and a few veggies for dinner. In other words, I've been careful to eat sufficient-but-not-too-much complete protein, to eat fat to provide energy, and to keep the carbs low. I don't eat until I'm full. I figure out what I need to eat and eat that. Then I stop. I have kept taking all my normal supplements and I've been drinking at least 60 ounces of water a day. The difference is that, by sipping black full-caffeine coffee whenever I start feeling between-meal hunger, I can put the hunger monster at bay. I hate the taste of the coffee, but the fact that I'm essentially using it as a drug seems to make that okay. I once again can eat three reasonable meals three times a day and be satisfied. Thoughts of food no longer rule my life.

In conclusion I'll do a little speculation. For some reason, my body seems to need a spike in epinephrine to switch from food-storage to fat-burning mode. And it seems to need several little spikes over time, rather than one big spike. That may be why certain over-the-counter (OTC) diet pills worked for me and others didn't. Most OTC diet pills contain caffeine in some form, but it may be that the three effective ones delivered the caffeine slowly enough to keep my fat burning process in motion. I've tried taking caffeine pills and those don't work for me. I've tried drinking cups of coffee and that doesn't work. There seems to be something about the slow ingestion of black coffee that makes the difference.

As I said, n=1. This may work for me and for nobody else. But I'm posting it in case somebody else is doing pure low-carb and finds it impossible to fight off between-meal hunger. Erasmus is a zero-carber who says his Satisfactometer is broken. I think my Satisfactometer is broken, too, but maybe, just maybe, I have found a way to cope with it. No guarantees, but in case this works for someone else, I thought I'd share.

Thursday, July 1, 2010

Organic Food versus Conventional Food

After people have low-carbed for a while, they start to look better and feel better. As their health improves, one of the natural questions to ask is, "If I feel this good by dropping the carbs, wouldn't I feel even better if I ate organic food?" When this question is asked in the form of scientific studies, the short answer is, "Probably not."

To be sure, the alternative medicine community makes many claims for organic food. In Alternative Medicine Review, Walter J. Crinnion, a Nutritional Doctor, states that organic foods contain higher levels of certain nutrients, lower levels of pesticides, and may provide health benefits for the consumer. Please click the link for an extensive list of references.

On the other hand, in 2010 in the American Journal of Clinical Nutrition, Dangour et al. interviewed experts, searched bibliographies, and checked peer-reviewed articles with English abstracts. They found a total of 12 studies that evaluated health effects following the use of organic compared with conventionally produced foods. The authors reported that the largest study showed a 36% reduction in risk for allergic eczema when children under two consumed organic dairy products. Other than that, the majority of the studies showed no differences resulting from organic foods versus conventionally produced foods in nutrition-related health outcomes.

In one sense, this is not surprising. A 2009 literature review by the same group showed that there were very few differences in nutrients between organic and conventionally produced foods. In crops, eleven nutrient categories were analyzed. Conventionally produced crops had a significantly higher content of nitrogen, while organically produced crops had a significantly higher phosphorus and more acidity. The other eight categories were not different between the two groups. An analysis of the database on livestock products found no differences in nutrients between organic and conventionally produced products.

This finding is supported by the UK Food Standards Agency which found that nutrient levels vary as a result of freshness, storage conditions, crop variety, soil conditions, weather conditions and how animals are fed, rather than as a function of whether the food is produced in an organic or a conventional manner. They caution that while single papers may show differences in the nutritional content of a particular food, it is important to evaluate the weight of evidence across a range of published papers.

An important consideration favoring organic food is that organically grown foods have about one third the pesticide residues as do conventionally grown foods. A study in elementary age children found that their urinary organophosphorus pesticide metabolites were significantly lower when a conventional diet was replaced by one with organic food items. However, chemical pesticides are not the only ones available. It is important to note that while organic farming does not allow the use of synthetic pesticides, it does permit the use of plant-derived pesticides including Bt, pyrethrins and rotenone, and all of these exhibit varying degrees of toxicity in humans.

Another concern is ecological rather than health-related. Organic farming requires more land per unit of food produced. Repeated use of soil for growing crops makes it necessary to use fertilizer. In place of chemical nitrates and ammonia, organic farmers must obtain and apply manure and use crop rotation with leguminous plants to return nitrogen to the soil. When soils are phosphate-depleted, conventional farmers can use highly soluble chemically-made superphosphate while organic farmers must use poorly soluble rock phosphate. These practices, along with the poorer efficiency of organic pesticides and the need to till the land frequently to prevent weeds, means that the production of food is up to 50% less efficient when it is done organically. (See Reference 15 here.)

Even if a country has plenty of land to devote to food production, there are a couple of other items that should be considered. The use of manure rather than chemicals as fertilizer introduces the presence of bacteria, especially in fruits and vegetables that are eaten fresh. Because organic food production does not use antibacterial techniques such as food irradiation or chemical washes, it is very important to wash organic foods before they are consumed. Finally, organic foods tend to spoil more quickly than their conventionally produced counterparts, which makes it necessary to buy them when they are fresh and to use them up quickly. This is especially important with grains, seeds and nuts which are liable to produce mold and its associated toxins.

As is frequently the case, I can't come down on one side or the other in the case of organic versus conventional food. Sometimes people have worries about the possible effects of agricultural chemicals. Sometimes they prefer the taste and smell of organically produced food. Sometimes they simply want to get back to a more natural way of living. If that's the case, and if they are aware that eating natural foods is not completely risk-free, then they should go ahead and buy organic food. But speaking from a scientific perspective, and looking at groups of people rather than at individuals, it's probably fine to buy and eat food that is produced in conventional ways.