Tuesday, June 28, 2011

Food Reward: a Dominant Factor in Obesity, Part VII

Now that I've explained the importance of food reward to obesity, and you're tired of reading about it, it's time to share my ideas on how to prevent and perhaps reverse fat gain.  First, I want to point out that although food reward is important, it's not the only factor.  Heritable factors (genetics and epigenetics), developmental factors (uterine environment, childhood diet), lifestyle factors (exercise, sleep, stress) and dietary factors besides reward also play a role.  That's why I called this series "a dominant factor in obesity", rather than "the dominant factor in obesity".
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Monday, June 27, 2011

Boring is another word for satiating

Satiety is a common topic of discussion on this blog. In the last few posts it came up several times in the comments’ sections. Also, in my interview with Jimmy Moore, we did talk a bit about satiety. I told him what has been my perception and that of many people I know, which is that the least satiating foods tend to be foods engineered by humans.

(Source: Wellnessuncovered.com)

There is another component to satiety, which applies to natural foods, or foods that are not man-made. That other component is the nutrition value of those foods, and whether they meet our nutrition needs at a given point in time. If our body needs certain essential amino acids for tissue repair, subconscious mechanisms will make us crave those foods from which those amino acids can be extracted. In this context, eating is generally a good idea.

The problem is that we have not evolved mechanisms to differentiate “true” from “fake” nutrient starvation; one example of the latter would be fat starvation due to transient hyperinsulinemia induced by refined carbohydrate-rich foods.

Foods engineered by humans tend to lead to overeating because humans are good engineers. In modern society, business drives everything. Food business is predicated on consumption, so engineered foods are designed so that one person will want to consume many units of a food item – typically something that will come in a box or a plastic bag. There is no conspiracy involved; the underlying reason is profit maximization.

When we look at nature, we typically see the opposite. Prey animals do not want to be eaten; often they fight back. Eggs have to be stolen. Plants do not want their various parts, such as leaves and roots, to be eaten. Much less their seeds; so they have developed various defense mechanisms, including toxins. Fruits are exceptions to this rule; they are the only natural foods that are designed to be eaten by animals.

Plants want animals to eat their fruits so that they can disperse the plants’ seeds. So they must be somewhat alluring to animals. Sugar plays a role here, but it certainly is not the only factor. The chemical composition of fruits is quite complex, and they usually contain a number of health-promoting substances, such as vitamins. For example, most fruits contain vitamin C, which happens to be a powerful antioxidant, and also has the ability to reversibly bind to proteins at the sites where sugar-induced glycation would occur.

Many modern fruits have been bred to be resistant to diseases, more palatable, and larger (usually due to more water retention). But, fundamentally, fruits are products of evolution. So how come we don’t see fruits that are pure sugar? Watermelons, for example, are often referred to as “bags of sugar”, but they are only 6 percent sugar. Ice cream is 25 percent sugar.

Two things must be kept in mind regarding fruits and their evolution. One is that dead animals do not eat fruit, and thus cannot disperse seeds. Sick animals would probably not be good candidates for fruit dispersion either. So the co-evolution of fruits and animals must have led fruits to incorporate many health-promoting attributes. The other is that seed dispersion success is correlated with the number of different animals that consume fruits from a plant. In other words, plants do not want all of their fruits to be eaten by one single animal, which must have led fruits to incorporate satiety-promoting attributes.

Often combining foods, adding spices, and so on, is perceived as making those foods exciting. That is so even with natural foods. If you read the descriptions of the foods consumed by healthy isolated populations in Weston Price’s Nutrition and Physical Degeneration, you will probably find them a bit boring. A few very nutritious food items, consumed day in and day out, frequently without heavy preparation. Exciting foods, requiring elaborate and time-consuming preparation, were consumed in special occasions. They were not eaten regularly.

The members of those healthy isolated populations were generally thin and yet lacked no important nutrients in their diet. They were generally free from degenerative diseases. Their teeth were normally strong and healthy.

Just before writing this post, I took six whole sardines out of the freezer to thaw. I will prepare them as discussed on this post, and eat them with a side of steamed vegetables for lunch. (I tend to eat fruits only on the days I exercise; typically 3 days out of 7.) This lunch will be very nutrient-dense. I will be very hungry before lunch, since I’ll have been fasting for 16 hours, and after I’ll not be hungry until dinner. Frankly, eating the sardines will not be very exciting, since I’ve been doing this for years.

Boring is another word for satiating.

Thursday, June 23, 2011

Drug Cessation and Weight Gain

Commenter "mem", who has been practicing healthcare for 30+ years, made an interesting remark that I think is relevant to this discussion:
Recovering substance dependent people often put on lots of weight and it is not uncommon for them to become obese or morbidly obese.
This relates to the question that commenter "Gunther Gatherer" and I have been pondering in the comments: can stimulating reward pathways through non-food stimuli influence body fatness?  

It's clear that smoking cigarettes, taking cocaine and certain other pleasure drugs suppress appetite and can prevent weight gain.  These drugs all activate dopamine-dependent reward centers, which is why they're addictive.  Cocaine in particular directly inhibits dopamine clearance from the synapse (neuron-neuron junction), increasing its availability for signaling.
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Monday, June 20, 2011

Maybe you should stop trying to be someone you are not

Many people struggle to lose body fat, and never quite make it to their optimal. Fewer people manage to do so successfully, and, as soon as they do, they want more. It is human nature. Often they will start trying to become someone they are not, or cannot be. That may lead to a lot of stress and frustration, and also health problems.

Some women have an idealized look in mind, and keep losing weight well beyond their ideal, down to anorexic levels. That leads to a number of health problems. For example, hormones approach starvation levels, causing fatigue and mood swings; susceptibility to infectious diseases increases significantly; and the low weight leads to osteopenia, which is a precursor to osteoporosis.

In men, often what happens is the opposite. Guys who are successful getting body fat to healthy levels next want to become very muscular, and fast. They have an idealized look in mind, and think they know how much they should weigh to get there. Sometimes they want to keep losing body fat and gaining muscle at the same time.

I frequently see men who already look very healthy, but who think that they should weigh more than they do. Since muscle gain is typically very slow, they start eating more and simply gain body fat. The reality is that people have different body frames, and their muscles are built slightly differently; these are things that influence body weight.

There are many other things that also influence body weight, such as the length of arms and legs, bone density, organ mass, as well as the amount of glycogen and water stored throughout the body. As a result, you can weigh a lot less than you think you should weigh, and look very good. The photo below (from MMAjunkie.com) is of Donald Cerrone, weighing in at 145 lbs. He is 6 ft (183 cm) tall.

Mr. Cerrone is a professional mixed martial arts (MMA) fighter from Texas; one of the best in professional MMA at the moment. Yes, he is a bit dehydrated on the photo above. But also keep in mind that his bone density is probably well above that of the average person, like that of most MMA fighters, which pushes his weight up.

A man can be 6 ft tall, weigh 145 lbs, and be very healthy and look very good. That may well be his ideal weight. A woman may be 5’5”, weigh 145 lbs, and also be very healthy and look very good. Figuring out the optimal is not easy, but trying to be someone you are not will probably be a losing battle.

Saturday, June 18, 2011

Food Reward: a Dominant Factor in Obesity, Part VI

Reward Centers can Modify the Body Fat Setpoint

Dopamine is a neurotransmitter (chemical that signals between neurons) that is a central mediator of reward and motivation in the brain.  It has been known for decades that dopamine injections into the brain suppress food intake, and that this is due primarily to its action in the hypothalamus, which is the main region that regulates body fatness (1).  Dopamine-producing neurons from reward centers contact neurons in the hypothalamus that regulate body fatness (2).  I recently came across a paper by a researcher named Dr. Hanno Pijl, from Leiden University in the Netherlands (3).  The paper is a nice overview of the evidence linking dopamine signaling with body fatness via its effects on the hypothalamus, and I recommend it to any scientists out there who want to read more about the concept.
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Monday, June 13, 2011

Alcohol intake increases LDL cholesterol, in some people

Occasionally I get emails from people experiencing odd fluctuations in health markers, and trying to figure out what is causing those fluctuations. Spikes in LDL cholesterol without any change in diet seem to be a common occurrence, especially in men.

LDL cholesterol is a reflection of many things. It is one of the least useful measures in standard lipid profiles, as a predictor of future health problems. Nevertheless, if one’s diet is not changing, whether it is high or low in fat, significant fluctuations in LDL cholesterol may signal a change in inflammatory status. Generally speaking, the more systemic inflammation, the higher is the measured LDL cholesterol.

Corella and colleagues (2001) looked into alcohol consumption and its effect on LDL cholesterol, as part of the Framingham Offspring Study. They split the data into three genotypes, which are allele combinations. Alleles are genes variations; that is, they are variations in the sections of DNA that have been identified as coding for observable traits. The table below summarizes what they have found. Take a look at the last two columns on the right.

As you can see, for men with the E2 genotype, alcohol consumption significantly decreases LDL cholesterol. For men with the E4 genotype, alcohol consumption significantly increases LDL cholesterol. No significant effects were observed in women. The figure below illustrates the magnitude of the effects observed in men.

On average, alcohol consumption was moderate, around 15 g per day, and did not vary significantly based on genotype. This is important. Otherwise one could argue that a particular genotype predisposed individuals to drink more, which would be a major confounder in this study. Other confounders were also ruled out through multivariate controls - e.g., fat and calorie intake, and smoking.

Alcohol consumption in moderation seems, on average, to be beneficial. But for some individuals, particularly men with a certain genotype, it may be advisable to completely abstain from alcohol consumption. Who are those folks? They are the ones for whom LDL cholesterol goes up significantly following moderate alcohol consumption.

Monday, June 6, 2011

What is a good low carbohydrate diet? It is a low calorie one

My interview with Jimmy Moore should be up on the day that this post becomes available. (I usually write my posts on weekends and schedule them for release at the beginning of the following weeks.) So the time is opportune for me to try to aswer this question: What is a good low carbohydrate diet?

For me, and many people I know, the answer is: a low calorie one. What this means, in simple terms, is that a good low carbohydrate diet is one with plenty of seafood and organ meats in it, and also plenty of veggies. These are low carbohydrate foods that are also naturally low in calories. Conversely, a low carbohydrate diet of mostly beef and eggs would be a high calorie one.

Seafood and organ meats provide essential fatty acids and are typically packed with nutrients. Because of that, they tend to be satiating. In fact, certain organ meats, such as beef liver, are so packed with nutrients that it is a good idea to limit their consumption. I suggest eating beef liver once or twice a week only. As for seafood, it seems like a good idea to me to get half of one’s protein from them.

Does this mean that the calories-in-calories-out idea is correct? No, and there is no need to resort to complicated and somewhat questionable feedback-loop arguments to prove that calories-in-calories-out is wrong. Just consider this hypothetical scenario; a thought experiment. Take two men, one 25 years of age and the other 65, both with the same weight. Put them on the same exact diet, on the same exact weight training regime, and keep everything else the same.

What will happen? Typically the 65-year-old will put on more body fat than the 25-year-old, and the latter will put on more lean body mass. This will happen in spite of the same exact calories-in-calories-out profile. Why? Because their hormonal mixes are different. The 65-year-old will typically have lower levels of circulating growth hormone and testosterone, both of which significantly affect body composition.

As you can see, it is not all about insulin, as has been argued many times before. In fact, average and/or fasting insulin may be the same for the 65- and 25-year-old men. And, still, the 65-year-old will have trouble keeping his body fat low and gaining muscle. There are other hormones involved, such as leptin and adiponectin, and probably several that we don’t know about yet.

A low carbohydrate diet appears to be ideal for many people, whether that is due to a particular health condition (e.g., diabetes) or simply due to a genetic makeup that favors this type of diet. By adopting a low carbohydrate diet with plenty of seafood, organ meats, and veggies, you will make it a low calorie diet. If that leads to a calorie deficit that is too large, you can always add a bit more of fat to it. For example, by cooking fish with butter and adding bacon to beef liver.

One scenario where I don’t see the above working well is if you are a competitive athlete who depletes a significant amount of muscle glycogen on a daily basis – e.g., 250 g or more. In this case, it will be very difficult to replenish glycogen only with protein, so the person will need more carbohydrates. He or she would need a protein intake in excess of 500 g per day for replenishing 250 g of glycogen only with protein.

Thursday, June 2, 2011

Food Reward: a Dominant Factor in Obesity, Part V

Non-industrial diets from a food reward perspective

In 21st century affluent nations, we have unprecedented control over what food crosses our lips.  We can buy nearly any fruit or vegetable in any season, and a massive processed food industry has sprung up to satisfy (or manufacture) our every craving.  Most people can afford exotic spices and herbs from around the world-- consider that only a hundred years ago, black pepper was a luxury item.  But our degree of control goes even deeper: over the last century, kitchen technology such as electric/gas stoves, refrigerators, microwaves and a variety of other now-indispensable devices have changed the way we prepare food at home (Megan J. Elias.  Food in the United States, 1890-1945). 

To help calibrate our thinking about the role of food reward (and food palatability) in human evolutionary history, I offer a few brief descriptions of contemporary hunter-gatherer and non-industrial agriculturalist diets.  What did they eat, and how did they prepare it? 
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