More than 1 in 5 Americans will put weight loss at the top of their New Year's resolutions, but 73 percent of them will give up before meeting their goal.

Why the huge failure rate? Many people fail because of big goals, such as a 50-pound weight loss, and the enormity of their commitment overwhelms them. However, a stealth ingredient in many of the foods you eat may be keeping those pounds from falling off — an additive called monosodium glutamate or MSG.

MSG is a flavor-enhancer used in many processed foods, but it's most associated with Chinese foods and the resulting "Chinese food headache." Many people are sensitive to MSG, complaining of nausea as well as headaches, and have begun checking ingredient lists to avoid it.

But MSG hides in many innocent-sounding ingredients, and the longer a list, the bigger the odds of the food containing MSG. Some experts believe that more than 80 percent of foods on store shelves have either MSG or ingredients that contain a derivative of MSG called free glutamate.

"Unfortunately, most of the MSG consumed in this country is done so unwittingly," Dr. Russell Blaylock tells Newsmax Health.

"This is because food processors have learned to hide the ingredient to prevent criticism from those who recognize MSG as harmful."

MSG has effects on the entire body:

Weight gain. Several studies have found that people who eat more MSG are more likely to be obese, regardless of how many calories they eat. Although the link between MSG and weight gain isn't clear, some researchers believe it may damage the hypothalamus area of the brain and affect the hormone leptin, which regulates appetite and metabolism.

"The effects of MSG are now so well-established that the substance is routinely used in experimental obesity studies on animals," says nationally renowned natural health expert and former neurosurgeon Dr. Russell Blaylock.

Dr. Blaylock warns that expectant moms should be especially careful to avoid MSG. "Mothers consuming foods containing MSG may be priming their children for gross obesity," he says "It is known that the placenta concentrates MSG, so that the amount reaching the baby may be significantly higher than the mother's dose."

COPD. "MSG can have devastating effects on the lungs of people with COPD, especially those with asthma," says Dr. Blaylock.

"The cells lining the bronchioles and alveoli contain a number of glutamate receptors, and high blood levels of glutamate can cause these receptors to overreact and lead to bronchiospasm. After a meal containing MSG, blood levels of glutamate can rise 30- to 50-fold higher than normal and remain elevated for hours.

"For some people, even small concentrations can cause a reaction, depending on the sensitivity of the pulmonary glutamate receptors," he says.

Irritable bowel syndrome. "MSG can stimulate the bowel muscles, resulting in diarrhea and cramping," says Dr. Blaylock. "And sensitivity to MSG is heightened when the bowel is inflamed due to irritable bowel syndrome, Crohn's disease, or ulcerative colitis.

Brain damage. MSG is an excitotoxin, which means it can overstimulate brain cells until they are damaged or die, says Dr. Blaylock, causing brain damage and perhaps triggering Alzheimer's disease, Parkinson's disease, and Lou Gehrig's disease. While he doesn't believe MSG and other food additives are the primary cause of autism, "I firmly believe they greatly aggravate it," he says. "It also most likely plays a significant role in ADHD and similar learning problems."

MSG isn't always listed on food labels and hides in many additives. "It hides under innocent-sounding names," says Dr. Blaylock.

According to Dr. Blaylock, these additives always contain MSG:

• Hydrolyzed vegetable protein
• Hydrolyzed protein
• Hydrolyzed soy protein
• Soy protein concentrate
• Soy protein isolate
• Soy sauce
• Textured protein
• Whey protein concentrate
• Plant protein extract
• Hydrolyzed oat flour
• Sodium caseinate
• Calcium caseinate
• Yeast extract
• Autolyzed yeast

These additives frequently contain MSG:

• Malt extract
• Bouillon
• Broth
• Stock
• Natural flavoring
• Seasoning
• Spices
• Carrageenan
• Enzymes