STORY BYYour body’s parts function like a big family: everyone is related, interdependent and vying for attention.
One member is finally finding its voice—and, in the weight-loss fight, is gaining respect. Leptin, researchers are discovering, is one of the most influential hormones—to the point of winning out over old-fashioned will power. Leptin regulates appetite, energy expenditure, body weight and fat, plus it tells the liver what to do with its glucose reserves.
“Your leptin level rises as you gain weight because this hormone is produced by fat cells,” says Karen Gibson, R.D., Women, Infants and Children (WIC) program director at The University of Texas Medical School at Houston. The hormone decreases as you lose weight.
One of leptin’s jobs is to signal the brain when the stomach is full so you will stop eating and a “normal” weight can be maintained. But, should an imbalance occur, this natural process is diverted and unwanted pounds emerge.
Research shows that when you put on the pounds, the body adjusts to the new levels of weight as well as new levels of leptin in the blood. Unfortunately, when you lose weight, several systems are fierce about returning to that higher level. There are major changes in your nervous system and thyroid. Appetite increases a lot.
All these alterations in your complicated body will probably cause you to regain those pounds. Have pity on your poor will power: with all these molecular mechanisms at work, it never had a chance.
Maintaining body weight after the pounds are lost was the focus of a recent investigation into the basic biology of human body-weight regulation. Ten subjects were put on a liquid diet to lose 10 percent of their body weight. After attaining that goal, they were given low injections of leptin to bring that hormone level back to where it was before the weight loss.
The hypothesis was that once the body had dieted and lost weight, the brain would perceive the new condition as the body being leptin-insufficient; then it would try to correct the situation. Previous studies showed that when a person loses 10 percent of their fat, the amount of leptin in the blood falls by 10 percent.
Michael Rosenbaum, M.D., director of the Columbia University Medical College study, determined leptin will not help people lose weight but could help in weight maintenance.
This answer could lead to a new class of weight-maintenance drugs designed to keep people from regaining lost weight. In reality, the pills will be tricking the brain into believing that leptin levels are higher than they really are.
The sponsor for this study and a current and longer clinical trial, enrolling 60 persons, is the National Institute of Diabetes and Digestive and Kidney Diseases.
If the leptin levels are too low or too high, you will always be hungry and never feel full. This process is complicated by two other hormones: insulin, which also regulates weight gain and increases appetite, and serotonin, which must be released if a feeling of fullness is to be achieved.
Getting off track can happen in childhood, the teen years or as an adult, and usually involves weight gain. Obesity opens the door to diabetes, heart disease, high blood pressure, stroke, sleep apnea, gallstones and some cancers (endometrial, breast and colon), as well as forms of arthritis. There may also be damage to your eyes, nervous system or kidneys.
“Weight gain is a result of poor food choices,” Gibson notes. “People eat too much fast food and too many snacks. There is an over-consumption of fruit juices, which contains a lot of sugar, which puts on the pounds.
“Many families buy at least one fast-food meal a day, sometimes more. This trend is growing and crosses all economic levels. They also buy fully-cooked, frozen foods to heat in the microwave.”
Many of those quick foods, especially for children, are fried and breaded, like chicken fingers. Children whose diets feature these foods prominently tend to be overweight.
“If you are obese or just trying to lose a few pounds, three changes will improve overall health and lower the leptin level naturally: exercise, complex carbohydrates, weight loss,” explains Bettina Mackenbach, R.D., L.D., pediatric nutrition specialist at Memorial Hermann Wellness Institute.
“Eating whole grain bread, brown rice and unrefined sugars and more fiber, such as beans and whole grains, plus fruits and vegetables can help accomplish this goal.”
Look for protein foods low in saturated fats. Dairy products low in fat, such as one percent milk, skim and soy milk, non-fat or low-fat cheese, are good choices. Decreasing your stress levels also helps lower the amount of cortisol, a stress hormone that plays a role in weight gain.
“If a patient has real trouble losing weight, I strongly recommend a visit to an endocrinologist to have his or her growth hormone level checked,” Machenbach observes. “If it is too low, leptin will not work effectively. If thyroid levels drop and leptin levels are low, the thyroid’s production will be hindered.”
With her patients, Mackenbach does not use the word “diet”. If they want structure, she provides a meal plan and explains calorie levels and food exchanges.
Being motivated and having will power are not enough. “Food is a symbol. Many people eat for emotional reasons, not because they are hungry. To help my patients realize why they eat too much, I encourage a food journal. This tracks hunger and fullness on a scale of zero to 10, the person’s thoughts and what is going on in their life. From this they can see patterns and the triggers for overeating and hopefully be motivated,” she notes.
The percentage of the U.S. population with health problems from obesity is on the rise. The National Center for Health Statistics reports that 30 percent of adults are obese and 16 percent of youth ages 6–19 are overweight; that’s nine million children.
UPDATED: 1-05-2007
Editorial Board | Legal Disclaimer | Privacy & Security | Contact Us
©2000-2006 Office of Institutional Advancement, UT-Houston
Karen Gibson, R.D., is the Women, Infants and Children (WIC) program director at the UT Medical School.
Microwaves and 'Erupted Hot Water Phenomena'
Hot-water eruption can occur if you use a microwave oven to super-heat water in a clean cup. ("Super-heated" means the water is hot beyond boiling temperature, although it shows no signs of boiling.)
A slight disturbance or movement may cause the water to violently explode out of the cup. There have been reports of serious skin burns or scalding injuries around people's hands and faces as a result of this phenomenon.
Adding materials such as instant coffee or sugar to the water before heating greatly reduces the risk of hot-water eruption. Also, follow the precautions and recommendations found in microwave oven instruction manuals; specifically the heating time.
