Weight Loss - Leptin: The Appetite-Suppressing Hormone

Sleep Away the Pounds: Optimize Your Sleep and Reset Your Metabolism for Maximum Weight Loss
by Cherie Calbom, John Calbom

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Leptin was discovered in 1994. It is manufactured in the fat cells and communicates to your brain when you should be hungry, eat, and begin fat creation. The name is derived from the Greek word leptos, which means "thin". It serves important functions in regulating body weight, metabolism, and reproductive function. Leptin plays a vital role in controlling the brain's hypothalamus activity, which in turn regulates much of the body's autonomic functions - the ones we don't think about, but which determine our health and affect our weight. Just how powerful is leptin in weight management? When leptin was given to mice, it helped reduce fat tissue and boosted insulin sensitivity. Research mice that lack leptin overeat to the point of morbid obesity.

Research conducted at Brown Medical School and Rhode Island Hospital, as well as Harvard Medical School and Beth Israel Deaconess Medical Center, has shown that leptin triggers production of the active form of the peptide AMSH - an appetite suppressant in the hypothalamus, the small area in the base of the brain that controls hunger and metabolism. Researchers say this peptide is one of the body's most powerful metabolism-boosting signals, sending a strong message to the brain to burn calories. This message is then sent to another part of the hypothalamus, where another peptide is released. This stimulates the pituitary gland, which in turn secretes a hormone that relays the message to the thyroid, the master gland of metabolism. Once activated, the thyroid spreads word to the body's cells to increase energy production. And voilà! You're on your way to burning calories and losing weight.

A research team at the University of Chicago reported at the 2001 Association of Professional Sleep Societies meeting in Chicago that in experiments, sleep-deprived volunteers showed leptin changes that promoted weight gain. Men who were allowed only four hours of sleep per night displayed a dip in leptin that was equivalent to that seen in people underfed by a thousand calories a day for three days. In other words, the leptin signal was telling the men's bodies that they were short about a thousand calories. That misleading signal could cue the body to slow metabolism, overstimulate appetite, and increase fat deposition.

Leptin plays a part in these physical responses

• Hunger
• Stress response
• Fat burning and storage
• Body temperature
• Heart rate
• Reproductive behavior
• Bone growth
• Blood sugar levels

Normal leptin levels or increasing leptin levels will not help everyone lose a large amount of weight. For some people, it's simply poor nutrition and lack of exercise that are causing them to tip the scales. But for many, the best diet and exercise program in the world won't work, nor will even the best stress-reduction protocol, unless they develop a good sleep plan, because it's lack of sleep that is causing an imbalance of leptin and the other important hormones that regulate appetite.

Just like everything else, some people are more susceptible to problems with leptin levels than others. Many people who try to lose weight can find it difficult, even if they eat smaller portions than trim people and exercise consistently - all due to problems with leptin, known as leptin resistance.

Leptin Resistance: A Weight Loss Nightmare

Do you often crave sweets, bread, cereal, pasta, crackers, chips, potatoes, soda pop, wine, or beer? Uncontrollable sugar or other carbohydrate cravings, stress eating, hypothyroid symptoms, low energy, and excess abdominal fat can be signs of leptin resistance. If any of these symptoms apply to you, there's a chance you may have developed leptin resistance.

A landmark study linking body weight to sleep In the November 2004 issue of the Journal of Clinical Endocrinology & Metabolism, Eve Van Cauter, PhD, and her research team at the Research Laboratory on Sleep, Chronobiology, and Neuroendocrinology at the University of Chicago School of Medicine reported that pre-breakfast concentrations of the satiety hormone leptin were roughly 20 percent lower in healthy men who had slept only four hours a night for nearly a week than when they had slept nine hours nightly. The study involved eleven healthy twenty-two-yearold men who spent consecutive nights in the university's sleep laboratory. For six days, they got only four hours of sleep per night. One year later, the men returned for a six-day study with an eight-hour sleep period, so they served as their own comparison group. After their six-day sleep-deprivation period, volunteers had a measurable leptin decrease ranging from 19 to 26 percent. This decrease indicated that an erroneous signal was sent by the brain that more food was needed when, in fact, enough food had been eaten. Since the men were getting the same amounts of calories and activity, leptin levels and appetite control should not have changed. In fact, they changed in a major way. The men craved more food and predominantly rich, fattening foods.

In this case, your brain does not detect your body's level of leptin properly and, therefore, does not know how much fat you have in storage. Your brain may think you are the perfect weight and, therefore, not tell your body to burn fat. Worse yet, it can signal that you are short on calories and cause you to want to eat more food, even when that's the last thing you need.

Studies suggest that the tongue is a target for leptin, and that leptin may be a sweet-sensing suppressor that may take part in regulation of food intake, states Dr. Kirio Kawai of Tokyo Medical and Dental University in Japan. In addition to suppressing the appetite, leptin appears to reduce cravings for sweets by targeting taste receptors on the tongue. Therefore, it is possible that a lack of leptin, or the body's failure to respond to this hormone due to defects in leptin receptors (known as leptin resistance), may contribute to the so-called sweet tooth and alcohol and carbohydrate cravings so many people struggle to overcome.

Since leptin is the hormone that controls ghrelin (the hormone that causes us to want to eat), it would seem logical that the more leptin present in the bloodstream, the better. That, however, is not true. When leptin was first discovered, scientists thought they had finally found the answer to obesity. But when they measured leptin levels in overweight people, they found that almost all of them were not leptin-deficient, but in fact had too much of this hormone. It turns out that many of these people were leptin-resistant, meaning they had lost their sensitivity to leptin in the same manner as many people become insulin-resistant, causing a higher level of leptin in their systems. (Leptin and insulin resistance are often at the root of blood sugar imbalance and the overwhelming urge to eat more food.)

Here's how the imbalance works. If you're leptin-resistant, it takes more and more leptin to signal your brain that your body is satisfied and doesn't need to eat more. Ron Rosedale, MD, says it's like people who grow progressively harder of hearing. The bell has to ring louder and louder for them to hear it. Eventually, they won't hear it at all. So it is with leptin resistance - the brain is not receiving leptin's message. Consequently, more and more fat is stored. Here's why. Fat cells make leptin. When people are leptin-resistant, more and more fat cells are perceived as needed to produce more leptin. It's a frustrating cycle. You're hungry because your brain tells you you're not storing enough fat. You eat more food because your brain sends you the signal to eat. The only way to stop eating is to produce more leptin, which means you need more fat - and that causes you to gain more weight. Thus you become more leptin- and insulin-resistant, which makes you keep eating, and eating, and eating.

To top it all off, you more than likely won't be sleeping well. The reason is that leptin resistance causes you to have higher amounts of adrenaline coursing through your body during the night hours when you should be sleeping. (Adrenaline is part of the fight-or-flight chemistry that gets your body going under stress.) So rather than dreaming of dancing sugarplums, you may be awake thinking about eating them. The more sleep-deprived you become, the more intolerant you are of stress. Adding to the fray at this point, even a little stress will elevate the hormone ghrelin, causing you to want to eat more food.

There are several signs that can indicate that you may have a problem with your leptin levels. These include:

• Sleeping less than seven to eight hours per night and feeling tired during the day
• Late-night eating
• Stress eating
• Weight gain around the middle
• Yo-yo dieting
• Low-thyroid symptoms
• Uncontrollable cravings, especially for sugar, alcohol, or simple carbohydrates
• Insomnia or other sleep disorders

This scenario is not counter to how we've been wired, however: We are actually designed for leptin and insulin resistance. It's true. People in times past feasted in summer and early fall when food was plentiful, to store fat for winter when food was scarce. Hence summer was a time to eat as much as possible, and as many carbs as possible (which were probably fruit and honey), so that enough weight could be gained to make it through the winter months. Our survival as a civilization depended on this biochemistry. Today our artificial lights and heat are on in the evening, we stay up late as though it were summer, and we eat carbs just like it was August or September. It's perfectly logical that our bodies think it's summer, causing many of us to become leptin- and insulin-resistant so we can "store fat for winter."

Copyright © 2007 by Cherie Calbom and John Calbom

About the Author

Cherie Calbom is known to millions of fans as "The Juice Lady," and her infomercials are world-renowned. A registered nutritionist, Cherie Calbom has become one of America's foremost celebrity experts on "drinking your vitamins." Her previous books, Juicing for High Level Wellness and Vibrant Good Looks (Crown, 1999), and Juice Lady's Guide to Juicing for Life (Avery, 1992).

John Calbom, MA, is director of Trinity Retreat House and vice president of Trinity Wellness Institute. He is a behavioral medicine specialist, organizational development consultant, Eastern Orthodox priest, and coauthor of The Complete Cancer Cleanse.