Why We Eat More than We Are Supposed To
May 26, 2012
By Dr. Mercola
Here are some questions posed by Dr. Robert Lustig, professor of pediatrics at the University of California, San Francisco.
- Why do we eat more than we are supposed to?
- Why are we eating more?
- What happened to make us eat more?
For 50,000 years or more, humans relied on a remarkable, naturally-occurring hormone called leptin to regulate what we ate, and it told our brains when we'd had enough. But somehow in recent years that regulator has become confused, and suddenly it seems like people just don't know how to stop eating.
So why are we eating more? The answer lies in understanding the biochemistry of the brain, where the signals that tell your body you're full are no longer working.
What Happens When Your Brain Can't Hear Leptin's Signals …
Leptin is a hormone produced by fat tissue, which relays important messages such as whether you should:
- Be hungry, eat and make more fat
- Reproduce and make babies
- "Hunker down" and work overtime to maintain and repair yourself
Although most think of their brain as being "top of the food chain" in terms of making decisions to keep your body functioning, your brain actually depends on your fat to "speak" to it and tell it how much energy your body has available, and then what to do with it.
Growing evidence shows that leptin may influence areas of your brain that control the intensity of your desire to eat. It has also been found that leptin not only changes brain chemistry, but can also "rewire" the very important areas of your brain that control hunger and metabolism. The way your body stores fat is a carefully regulated process that is controlled, primarily, by leptin. If you gain excess weight, the additional fat produces extra leptin that should alert your brain that your body should stop creating and storing more fat and start burning the accumulated excess.
To do this, signals are sent to your brain to stop being hungry and to stop eating. It is very important that your brain is able to accurately "hear" the messages leptin sends it, as otherwise your brain thinks you're depleted and will continue to feel hungry, even starving. If your brain does not respond appropriately to leptin, you will likely continue to eat and store more fat.
So why then, if your body has an innate system, honed by eons of trial and error to regulate your fat stores to perfection, is the United States and many other countries facing an obesity epidemic of unprecedented scale?
Because many people have become "leptin resistant."
Leptin resistance occurs when your body is unable to properly hear leptin's signals. How does this happen? By overexposure to high levels of the hormone, caused by eating too much sugar.
You may be familiar with this process occurring with the hormone insulin. High blood sugar levels cause repeated surges in insulin and this causes your cells to become "insulin-resistant," which leads to the production of even higher levels of insulin, eventually leading to type 2 diabetes. It is much the same as being in a room with a strong odor for a period of time. Eventually, you stop being able to smell it, because the signal no longer gets through.
The same process also occurs with leptin. It has been shown that as sugar gets metabolized and stored as triglycerides in fat cells, the fat cells release surges of leptin and those surges result in leptin-resistance, just as it results in insulin-resistance. When you become leptin-resistant, your body can no longer hear the messages telling it to stop eating and burn fat -- so it remains hungry and stores more fat.
This will not only contribute to weight gain, but also increase your risk of many chronic illnesses, as leptin plays a significant, if not primary, role in heart disease, obesity, diabetes, osteoporosis, autoimmune diseases, reproductive disorders, and perhaps the rate of aging itself.
Too Much Sugar Overstimulates Your Brain's Pleasure Center, Leading to Addiction
When you eat sugar it triggers the production of your brain's natural opioids -- a key initiator of the addiction process. Your brain essentially becomes addicted to stimulating the release of its own opioids. The intensity of this effect is experienced on the same level as morphine or heroin.
Researchers have speculated that the sweet receptors (two protein receptors located on your tongue), which evolved in ancestral times when the diet was very low in sugar, have not adapted to the seemingly unlimited access to a cheap and omnipresent sugar supply in the modern diet. Therefore, the abnormally high stimulation of these receptors by our sugar-rich diets generates excessive reward signals in your brain, which have the potential to override normal self-control mechanisms, create tolerance and withdrawal symptoms, thus leading to addiction.
According to Dr. Lustig, it is virtually impossible to exert enough cognitive willpower to overcome this 24/7 biochemical drive! He states in The Atlantic:i
"The brain's pleasure center, called the nucleus accumbens, is essential for our survival as a species... Turn off pleasure, and you turn off the will to live... But long-term stimulation of the pleasure center drives the process of addiction... When you consume any substance of abuse, including sugar, the nucleus accumbens receives a dopamine signal, from which you experience pleasure. And so you consume more. The problem is that with prolonged exposure, the signal attenuates, gets weaker. So you have to consume more to get the same effect -- tolerance.
And if you pull back on the substance, you go into withdrawal. Tolerance and withdrawal constitute addiction. And make no mistake, sugar is addictive."
Tolerance and withdrawal are the hallmarks of addiction – they occur with alcohol, nicotine, cocaine, morphine, cannabis and every drug of abuse … and also with sugar. Like many types of addictions, sugar addiction can in fact be deadly. Evidence is mounting that sugar is a primary contributing factor in obesity and diabetes, but other chronic and lethal diseases.
There's really no doubt anymore that sugar is indeed toxic to your body, and it's only a matter of time before it will be commonly accepted as a causative factor in most cancer, in the same way that now we accept without question that smoking and alcohol abuse are direct causes of lung cancer and cirrhosis of the liver, respectively.
The Average American Consumes 12 Teaspoons of Sugar a Day
… This amounts to about two TONS of sugar during a lifetime. While it may offer a fleeting feeling of pleasure when it passes through your lips, the more you eat the more you'll crave – and ultimately the more you'll need to eat to get those same pleasurable feelings. This sugar addiction can actually re-wire your brain, not to mention make you very sick …
Of all the molecules capable of inflicting damage in your body, sugar molecules are probably the most damaging.
Fructose, in particular, is an extremely potent pro-inflammatory agent that creates harmful advanced glycation end products (AGEs) and speeds up the aging process. It also promotes the kind of dangerous growth of fat cells around your vital organs (visceral fat) that are the hallmark of diabetes and heart disease. As mentioned, sugar/fructose also increases your insulin and leptin levels and decrease the receptor sensitivity for both of these vital hormones, and these hormonal abnormalities are a major factor in premature aging and age-related chronic degenerative diseases such as heart disease.
Keep in mind that while it's perfectly normal for your blood sugar levels to rise slightly after every meal, it is not natural or healthy when your blood sugar levels become excessively elevated and stay that way -- which is exactly what will happen if you're eating like the typical American, who consumes on average a staggering 2.5 pounds of sugar a week!
And when you add in other low-quality carbohydrate-rich foods such as white bread, sugar, pasta, pastries, cookies, and candy, which also break down to sugar (starch is broken down into glucose) in your body and often contain added sugar as well, it's not so difficult to see why so many Americans are in such poor health.
Can You Stop Eating So Much Sugar?
While Dr. Lustig believes the biochemical drive to consume sugar and overeat is virtually unstoppable, limiting or eliminating your sugar intake is the most effective way to break free from this disease-causing cycle. If you still want to use a sweetener occasionally, the sweet herb stevia makes a good, non-addictive sugar substitute. (It is important to avoid ALL artificial sweeteners, which can damage your health even more quickly than sugar.)
If you currently eat sugar, there's a good chance you're struggling with sugar addiction.
So I highly recommend trying an energy psychology technique called Turbo Tapping, which has helped many "soda addicts" kick their sweet habit, and it should work for any type of sweet craving you may have. Remember that in order to minimize your sugar intake, you need to avoid most processed foods, as most contain added sugar. Even savory foods like salad dressing, soup, and bread often contain sugar. For optimal health, eat natural whole foods primarily, and limit your fructose consumption to below 25 grams per day, including that from fresh fruit.
A couple of other tricks to try to kick your sugar cravings:
- Exercise: Anyone who exercises intensely on a regular basis will know that significant amounts of cardiovascular exercise is one of the best "cures" for food cravings. It always amazes me how my appetite, especially for sweets, dramatically decreases after a good workout. I believe the mechanism is related to the dramatic reduction in insulin levels that occurs after exercise.
- Organic, black coffee: Coffee is a potent opioid receptor antagonist, and contains compounds such as cafestrol -- found plentifully in both caffeinated and decaffeinated coffee -- which can bind to your opioid receptors, occupy them and essentially block your addiction to other opioid-releasing foods.ii,iii This may profoundly reduce the addictive power of other substances, such as sugar.