FACTOID
About 95 percent of your body’s serotonin is found in your intestines, while your central nervous system has only 2 percent to 3 percent. Remember, serotonin is what helps control depression in your brain.
FACTOID
The additive olestra looks like a fat cooks like a fat, and tastes like a fat, but is not a fat and isn’t absorbed as a fat-which is why it’s used in some food products to lower their fat and calorie contents. The problem is that olestra gives your stools the consistency of tea and sucks away some of the valuable fat-soluble vitamins, especially carotenoids. So it’s smart to eats lots of yellow and green vegetables if you’re eating chips made with olestra. By the way, the official name of olestra provides a useful insight into its mechanism of action: “sucrose polyester.”
When people are under stress, their bodies release high amounts of steroids into their bloodstream in the form of the hormone cortisol. In acute cases (the tiger or a car accident), steroids stick around briefly. But when you’re under chronic stress (the drought or the nagging task), your body needs to find a way to deal with those high levels of cortisol. So your omentum clears the cortisol steroids; it has receptors that bind to them and can suck them out of the bloodstream. (Unfortunately, this doesn’t necessarily reduce the stress level that you feel.) The steroids turbocharge the ability of omentum to store fat, so your belly fat (and subsequent waist size) becomes the best surrogate indicator of how well you are really coping with stress—despite what your brain might be claiming. That uptake of steroids throws your body into metabolic disarray by making your omentum resistant to insulin so that sugar floats around without being absorbed and used appropriately by needy cells. This:
chronically raises your blood sugar, which damages your tissues;
supercharges your omentum with inflammatory chemicals that destabilize the delicate equilibrium of your hormones;
forces your omentum to pump high-octane fat directly into your liver—causing your liver to make even more inflammatory chemicals.
Figure 4.3 Toxic Dump All the nutrients we absorb through the intestines pass through the liver via the portal vein. Excess fat and inflammatory chemicals stored in the omentum can dump directly into the liver as well which can start a cascade of toxic protein release into the body.
The Fight Against Inflammation
The liver—the organ that’s responsible for your metabolism—receives its blood and nutrients from your gut. What it wants isn’t the trans fat from the extra-large fries. It wants the other nutrients: the protein from the meat, the carbohydrates from the bun, the lycopene from the tomato, the calcium from the cheese. The liver is always on the job, processing munchies after midnight, as well as 5 a.m. coffee. Your liver takes every chemical in your body and processes it by binding it to a protein, transforming it into something the body can use.
FACTOID
Preliminary studies in animals show that the scent of grapefruit oil-yes, just the scent-has an effect of reducing the appetite and body weight. Rats exposed to the scents for fifteen minutes three times a week enjoyed the effect. The cause? It’s unclear, but it may work through grapefruit oil’s effects on liver enzymes. Grapefruit oil is widely available through aromatherapy stores and websites. As a bonus, try to eat a couple of grapefruit while you’re searching.
So your poor overworked liver also gets the toxic trans fat directly from your intestines and from your omentum via that portal vein that feeds right into it. When your intestines send that convoy of fat pouring down into the vein, the liver sees it as a runaway train and tries to metabolize the foods. But in defending the body, additional inflammatory chemicals are released. In your liver, nutrients can be met by two substances. In our digestive town along our intestinal highway, let’s think of one as the raucous frat house that stimulates inflammation, while the other is a nice, stately nonprofit group that quiets inflammation and performs good deeds throughout your body.
Infected and Inflated
While it’s true that everything from your hair to that ankle tattoo technically belongs to you, the truth is that only 10 percent of the cells on and in your body are actually yours. The rest are microbes living on your skin and in your orifices (pleasant visual, eh?), and especially in your gut. Those gut-residing microbes provide the enzymes you need to digest the fiber in fruits and vegetables that would otherwise pass through your system without being absorbed (pleasant visual number two). That’s right. Without the bacteria and viruses in your gut the food-label warning about 100 calories per bite would be a gross exaggeration. Specifically, mice raised without exposure to any germs have 60 percent less body fat than ordinary mice, even though they eat 30 percent more food. More intriguingly, common gut bacteria inhibit proteins that normally prevent the body from depositing fat, so infected mice have more belly fat.
So what do a few blubbery mice have to do with obesity in humans? It turns out that people infected with a specific chicken virus in India carry an extra 33 pounds of fat compared with noninfected humans. More important they have lower cholesterol and triglyceride levels-just the opposite of what we expect with weight gain. Why? Perhaps because the germs in the gut also digest cholesterol, so that less of it is absorbed. In an American study, the virus was found in 30 percent of obese subjects compared to only 11 percent of leaner people, and the folks who had the virus weighed significantly more than uninfected people. (And when twins with only one infected sibling are examined, the infected twin has 2 percent more body fat, despite having the same genes.)
Finally, we know that fat cells and our immune cells share lots of similarities. Fat cells can engulf bacteria and can secrete hormones that stimulate the immune system, possibly explaining why obesity causes an inflammatory response and leads to elevated C-reactive protein (a marker of inflammation). So how do you tell if you have a germ civil war inside you that’s causing obesity? If your cholesterol and triglyceride levels are low and your C-reactive protein level is elevated, it might be worth testing yourself; Obetech (www.obesityvirus.com ) makes a kit. This might reduce your guilt level, but since science is still gathering data and a cure is still lacking, you will still need to focus on other approaches. At least for now anyway.
Eating foods that stimulate your liver to release the frat-house substance—which is called nuclear factor kappa B, or NF-kappa B—triggers a chain of events that causes the inflammation in your body and prevents the transport of glucose to your cells (and thus triggers hunger). Glucose (sugar) on the inside of cells stops hunger (in the specific satiety center of the brain). But you can also eat foods that stop the inflammation riot or foods that stimulate the release of the do-good substances that have an anti-inflammatory effect (see Figure 4.4). They’re called PPARs (it stands for peroxisome proliferator-activated receptors, but we like to think of them as Perfectly Powerful Abdominal Regulators). The reason PPARs are so effective: Once they’re activated, they decrease glucose and insulin levels, as well as cholesterol and inflammation. Though we all have different genetic dispositions for levels of PPARs, PPARs aren’t self-starters; they need to be activated by foods to work.
Help on the Horizon
“Fat-free” can refer to marathoners and teen pop stars, but when you see it referring to food, you have to be skeptical. That’s because either it tastes like a shoe box or it can be loaded with lots of sugar to compensate for fat-making that “fat-free” food more dangerous than a slowpoke in the passing lane. One goal for food manufacturers is to make foods that allow eaters to have the best of both worlds: great-tasting food that doesn’t have waist-expanding ingredients. One such substance that may eventually change the way we eat is called Z-trim-it’s a natural, zero-calorie fat substitute that’s made from the fiber of such ingredients as oats, soy, rice, and barley. While there’s no clinical data showing its effectiveness in weight loss, there’s