Have you ever wondered why some people are very active while others prefer to conserve their energy? People tend to keep preferred levels of activity, almost as part of their personalities. Those who are highly active may prefer lots of sports or just lots of fidgeting. They get antsy when confined. Others relax whenever possible. The ActivityStat is a term for a person’s general level of activity. “The ActivityStat hypothesis” suggests that when physical activity is increased or decreased in one domain, there will be a compensatory change in another domain, in order to maintain an overall stable level of physical activity or energy expenditure over time.” The ActivityStat leads people to maintain a certain level of activity. A person whose ActivityStat is high would probably fidget more or get up 20 times to get coffee when confined. Person whose ActivityStat is low might reduce activity for the rest of the day after a workout or play session. What determines a person’s activitystat is unknown. It might be genetic. But it may also be influenced by the environment.
The obesity epidemic is disturbing and fascinating as well. And while many have been quick to blame parents, the internet, schools and “moral failings,” there is growing evidence that unseen and poorly understood factors are involved, at least in part. These factors include current or early exposure to chemicals that have entered the environment or otherwise found their way to our food and water supplies. BPA, found in some plastics, has been a hot-button chemical. It was one of the first identified as an “endocrine disruptor” (a chemical that interacts with hormones or their receptors). While there has been a ton of research on BPA, new things keep turning up: male rats exposed to BPA very early in life, don’t move around as much as unexposed rats.
Can BPA make you gain weight? BPA also increases fat cells.
While BPA may decrease your activity stat, it also increases fat cells. At least in vitro (this is cells in a dish, rather than in a living animal). When a person is exposed to BPA, the body gets rid of it pretty quickly. It converts it to something called BPA-G. Until recently it was thought the BPA-G was harmless and could be urinated away. BPA-G added to a cell culture of potential fat cells caused the not-yet-fat cells to turn into fat cells. It also caused them to start making more fat. There may be no need to fear the occasional drink from a plastic water bottle. But people should probably stay away when possible. Especially pregnant women. Even if it says BPA-free on the label. We are just learning about BPA-free plastics, and it looks like they are much like BPA. A last word . . . these studies were of cells (or rats) eposed to BPA or BPA-G early on. The same effect may not be seen in adults. Or even humans for that matter. My apologies if this is too technical or not technical enough. For you geeks, links to the original articles are below.
The author on a great hair day.
NOTE: This is a disclaimer. I am not a medical doctor, I am a scientist. If you have questions about your health, talk to your medical doctor
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Obesity genetics and bacteria are strange bedfellows. The causes of obesity are far more complicated than we thought just a few short years ago. Diet and exercise are important, for sure. But scientists are discovering that genetics and the gut microbiome are be key factors too. The gut microbiome, if you didn’t know, are the trillions of bacteria that reside in our digestive tracts. New research has uncovered a piece of how genetics and bacteria interact to increase the chances that someone will become obese, or develop diabetes.
Obesity Genetics and Bacteria Nutshell
Most of us will remember that people can’t digest plant fiber. That is why we don’t bother to eat grass. Or leaves. Or at least most leaves . . . the kind on trees. Or shrubberies. Cows and other hoofed animals can eat these things because their stomachs are designed differently. Bacteria in a cow’s stomach have time to ferment grass and such and break down all those long cellulose chains into useable starch for the cow. It turns out, however, that some gut bacteria in humans can break down plant fiber into short chain fatty acids. Humans can then take these fatty acids and convert them into fat.
Obesity and Genetics.
Here comes the genetics part: While we host trillions of bacteria, we also control their populations. Overgrowth of bacteria is controlled by a gene called TLR5. People whose TLR5 doesn’t work that well cannot control gut bacteria as well. About 10% of our population has a mutated TLR5 that just doesn’t work. At all. Having this mutation increases your risk of metabolic syndrome: obesity, diabetes and cardiovascular disease. Having this mutation also increases fat deposits in the liver. If you are incredibly geeky (happy emoticom) you can read this “just out” article on genetics and obesity and bacteria here. If you are less technically oriented, hopefully this information will of help as it is. If you are struggling with your weight and trying to stay healthy, keep up the good work. It actually is harder for some people than it is for others. Different people can actually eat the same thing, and get different amounts of calories out of it.
Back in the old days having this mutation might have been beneficial. You would have been able to extract more energy from food, which would have been great in times of famine. But we now live in a time of excess.
Weight loss and CrossFit. Weight loss is hard for most people. Maybe harder than Crossfit. And there many different factors involved in weight gain. One of the things that differs in people is the ability to taste bitterness. Food does not taste the same to everyone. And some people seem to be more “into” food than others. They seem to get much more pleasure out of food than others. There’s an entire foodie culture with clubs and magazines. Even among hard core “Paleo Diet” CrossFit ers. Note the many Paleo websites and Paleo recipes out there. Then there are people who would be happy eating peanut butter sandwiches three meals a day. Who just don’t get what is so great about Cheetos. These people tend to have no problem with weight loss. What’s with that?
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This infant has a non-taster father and a prop-taster mother. Both parents follow the paleo diet.
People who perceive bitterness intensely tend to have lower BMI, lower food intake and different levels of appetite-regulators in their blood streams. Some things taste not so good to them. In fact, some things will taste very nasty. Some people don’t notice a thing. The difference between them is genetic. You can tell if someone has the gene for tasting the bitter by use of a simple test strip. The strip is a small piece paper coated with 6-n-propylthiouracil. Call it PROP. Ask a group of family and friends gathered around a Thanksgiving dinner table to taste one of these PROP strips. Chances are some will taste nothing. Others will taste a mildly bitter flavor. And a few will be running to the sink spitting and then scrubbing their tongues with a scouring pad. Who knew your auntie could behave like that in front of everyone?
People who are insensitive to PROP (can’t taste it) tend to eat more than other people. They also tend to prefer strongly flavored, fatty foods, have a higher BMI, and are more likely to be obese. The are also more likely to eat purely for the enjoyment of it. That is also called hedonic eating. As in hedonism.
Weight loss: Food makes some people “high” but not other people?
Appetite is regulated partly by endocannabinoids. Think cannabis. And pot. And runner’s high. Endocannabinoids are natural regulators of appetite. People who are non-tasters have endocannabinoid levels that are significantly different from those of tasters. The way the body regulates food intake and maintains body weight differs between these two groups. Even when both of them are of the same BMI (body mass index). This may not mean that some people get a greater high from eating. But it might. It might also mean that in the future people may be able to control their weight by altering endocannabinoids. Taking a bit of a jump here, but as physical activity alters endocannabinoids, and physical activity supresses appetite (up to a point), maybe here’s another reason to exercise. Especially if you test positive for PROP tasting. More research will tell.
Tomassini Barbarossa I, Carta G, Murru E, Melis M, Zonza A, Vacca C, Muroni P, Di Marzo V, & Banni S (2013). Taste sensitivity to 6-n-propylthiouracil is associated with endocannabinoid plasma levels in normal-weight individuals. Nutrition (Burbank, Los Angeles County, Calif.), 29 (3), 531-6 PMID: 23398921
Intake of vegetable protein is negatively correlated with waist circumference and BMI. In contrast, intake of animal protein is positively correlated with waist circumference and BMI, at least in Belgians. There are a lot of questions to raise with this including the possibility that people who eat less animal protein consume less animal fat which can be a rich source of bioactive, lipophilic contaminants which may also be endocrine disruptors that increase adiposity or alter blood lipids. Note Ruzzin et. al.’s April 2010 paper “Persistent Organic Pollutant Exposure Leads to Insulin Resistance Syndrome.” (Very nice work! Congratulations to all authors.) Also possible that people who eat a lot of vegetable protein also eat fewer calories, are less sedentary etc. There is also the argument that lean, grass-fed animals (happy cattle, miserable chickens) would eliminate this vulnerability in meat eaters. That would be an interesting study. BMI and blood lipid profiles in matched cohorts of grass-fed/organic animal protein eaters vs. regular grocery store consumers. Anyone . . . ?
Ruzzin J, Petersen R, Meugnier E, Madsen L, Lock EJ, Lillefosse H, Ma T, Pesenti S, Sonne SB, Marstrand TT, Malde MK, Du ZY, Chavey C, Fajas L, Lundebye AK, Brand CL, Vidal H, Kristiansen K, & Frøyland L (2010). Persistent organic pollutant exposure leads to insulin resistance syndrome. Environmental health perspectives, 118 (4), 465-71 PMID: 20064776Lin, Y., Bolca, S., Vandevijvere, S., De Vriese, S., Mouratidou, T., De Neve, M., Polet, A., Van Oyen, H., Van Camp, J., De Backer, G., De Henauw, S., & Huybrechts, I. (2010). Plant and animal protein intake and its association with overweight and obesity among the Belgian population British Journal of Nutrition, 1-11 DOI: 10.1017/S0007114510004642