A variety of hormones play a role in controlling your appetite, and one of the most important is leptin. Leptin is a hormone produced by fat cells when energy stores are high. Once produced, it feeds back to the brain to shut down the urge to eat. In other words, it helps you say no to the creme-filled chocolate doughnuts they’re passing around at the office. But if leptin works so well, why is there an epidemic of obesity in this country? The reality is some people who are overweight or obese actually have too much leptin floating around in their bloodstream due to a phenomenon called leptin resistance.
What is Leptin Resistance?
You’ve probably heard of insulin resistance, a condition where cells become less responsive to insulin the pancreas produces because there’s so much of it around. Leptin resistance is a very similar phenomenon. Under normal conditions, fat cells produce leptin when stores of energy are high. Leptin feeds back to the portion of the brain called the hypothalamus that controls the desire to eat. This shuts down appetite and increases the ability to mobilize fat stores as an energy source.
Likewise, when energy stores are low, leptin levels are depressed. This stimulates the desire to eat and slows down the rate at which you burn fat. Of course, leptin doesn’t act alone. A number of other appetite hormones and hormones that affect metabolism come into play including ghrelin, insulin, GLP-1, CCK and more, but leptin is a major player.
Back in the 1990s, scientists thought they had a possible cure for obesity. If leptin suppresses appetite and boosts metabolism, why not inject obese people with leptin? It sounded like a good idea, but there was one problem. Many obese people actually have too much leptin floating around in their bloodstream, and it doesn’t help them control their appetite or lose weight.
Why might this be? In a situation markedly similar to insulin resistance, obese people have plenty of leptin, but the leptin they have does little to suppress their appetite. The reason? Their body is flooded with large amounts of leptin from their excess fat cells, and their leptin receptors have become “immune” or unresponsive to the leptin they produce. Injecting obese people with leptin would have little benefit since they already have more than they need. The problem is with the receptors – not a lack of leptin.
Reversing Leptin Resistance
If there were a simple way to make the leptin receptors more responsive, leptin could again do its job of regulating appetite and metabolism. Unfortunately, leptin resistance isn’t easy to correct. One theory is that chronic inflammation contributes to leptin resistance. In an article published in Life Extension Magazine, the authors discuss research suggesting that elevated levels of a marker called CRP contribute to leptin resistance. When CRP levels are high, it binds to leptin and keeps it from binding to leptin receptors in the brain where it could do its job of controlling appetite. CRP
or c-reactive protein is a marker for inflammation. For this reason, reducing inflammation should have an impact.
Some ways to reduce chronic inflammation include regular physical exercise and limiting pro-inflammatory foods and foods that cause insulin spikes. These include most processed carbs, fast foods, and many packaged foods. Avoiding these foods lowers blood triglyceride levels, and triglycerides block movement of leptin into the brain. Other foods that reduce inflammation are fresh fruits and vegetables, fatty fish that contain omega-3 fats and some spices like turmeric. Losing weight also improves insulin resistance, although weight loss is more challenging when you have this problem. Life Extension magazine is studying the seeds of a fruit called Irvingia gabonensis that blocks the effects of CRP on leptin and may help to reverse leptin resistance.
There’s even more incentive to find ways to reduce leptin resistance. High levels of leptin have been linked with a greater risk of some types of cancer including breast cancer. They also appear to elevate blood pressure and increase risk factors for heart disease.
The Bottom Line?
Leptin resistance is a common problem among people who are overweight and obese, and it makes it considerably more challenging to lose weight and maintain it. There are natural ways to reduce inflammation, which should have an impact on leptin resistance. Eliminate processed foods and high-glycemic carbs, and add more fruits, vegetables and fatty fish to your diet.
References:
Life Extension Magazine. Irvingia: Understanding the Risks of Leptin Resistance”
Medscape.com. “Leptin-Based Therapeutics”
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