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Can we outsmart our appetite hormones?


July 2007 Dip Image 2

One major reason why even the best nutritional plan sometimes falls short of producing terrific results is a human frailty that can be summed up in a single word: Appetite. 

Scientists have been hard at work trying to decode the arcane mysteries of the human appetite−and it’s not a moment too soon.  Good nutritional principles−like those of the Atkins Advantage−have a two-sided benefit. On the one hand, they help us to stay healthy and energetic and maintain a healthy body weight. That we know. But the other, perhaps less talked about Advantage is that they help control and modulate appetite.

In some sense, our large appetites are built into our DNA because they helped us to survive in times of famine. Trouble is, the eating habits that allowed us to store fat in order to weather conditions of scarcity are extremely ill-suited to conditions of plenty. Genetically, we’re well adapted for the wilderness; not so much for the all-night supermarkets, convenience stores, 24-hour fast food restaurants and typical restaurant portions that could feed a grown man for four days. As scientists continue to discover new hormones and pathways that affect our appetite, we’re given a unique opportunity to learn to outsmart them. In modern life, it’s more important than ever to eat in a way that doesn’t rev up these appetite centers to the “full speed ahead” setting.


Take the hormone ghrelin, first identified a mere eight years ago. Ghrelin, also known (like insulin) as a “hunger hormone,” is made in stomach cells that stimulate appetite. Ghrelin levels rise before meals (saying “Feed me, feed me”) and then decrease after we eat. Worse, they go up not just when we need to eat, but when we expect to eat (much like Pavlov’s dogs were conditioned to salivate when a bell rang because they were trained to expect a steak to be forthcoming). Luckily, our body makes a couple of other appetite hormones that help moderate the effect of ghrelin. Otherwise−since we’re constantly exposed to visual food invitations−we’d be secreting ghrelin all the time and eating all day long. These hormones−notably one called choleocystokinin, or CCK−is released in the gut once you start eating; it’s one of the triggers that lets your brain know you’ve had enough. Trouble is, many of us eat so fast that we don’t give it a chance to work, and by the time it makes its way to the brain, we’re stuffed to the gills. Bottom line: Mom was right. Chew your food, eat slowly, and give the little guy a chance to deliver the “stop” message. It’s a great way to outsmart the hormonal imperative to eat more.

 

Then there’s leptin. Leptin is an appetite-suppressing hormone that created quite a buzz when it was first discovered in 1994. Researchers reasoned that since leptin plays a central role in communicating to the brain that the body is full, obese folks probably don’t have enough of it. They hoped that if they injected leptin into overweight subjects, they would suddenly lose their cravings for more food. But it didn’t work out that way.

 

Instead, research has shown that obese people have plenty of leptin. It just seems to not get to the target receptor sites in the brain. At a recent conference of the Metabolism and Nutrition Society, researchers discussed the concept of leptin resistance−the cells simply get tired of listening to leptin, and stop paying attention to it. Instead of shutting down the appetite centers when you’ve eaten enough food, the brain cells simply ignore the leptin “stop” signal, and you go on eating. Interestingly, the same researchers postulate that high levels of triglycerides are intimately associated with leptin resistance, and in fact that triglycerides may be partly responsible for preventing leptin from doing its job.  What to do? Lower your triglycerides!  Here again, we have a great  way to outsmart the hormonal imperative to overeat. And there’s a tried and true, research-tested way to lower triglycerides: Follow the principles of the Atkins Advantage. It works every time.

 

An overwhelming amount of research has shown that following a low-glycemic diet, with high fiber, lots of vegetables, adequate protein and good fat and with an absolute minimum amount of high-sugar foods−all principles of the Atkins Advantage− consistently lowers triglycerides. In virtually every head-to-head diet comparison, whatever other results may or may not have been demonstrated, the lowering of triglycerides was a consistent finding in people following dietary strategies based on the principles of the Atkins Advantage. Lowering your triglycerides has a lot of health benefits, but it also may help you control your appetite by allowing leptin to function more effectively. And, here’s the kicker: Because leptin is produced by body fat, regulating appetite ultimately leads to lower amounts of body fat−which has the paradoxical effect of making leptin work even more efficiently!

 

Another hormone that plays an indirect role in appetite regulation is adeiponectin. Adiponectin is a “good guy”−it’s a strong regulator of sugar and fat metabolism, and there’s a proven relationship between adiponectin, BMI (a measure of overweight) and body composition. Adiponectin helps fat to burn in the body. It’s also anti-inflammatory, and has protective effects against atherosclerosis. But here’s the interesting thing from an appetite point of view: Low levels of adiponectin are associated with insulin resistance, and insulin resistance is associated with metabolic syndrome, obesity and diabetes. You can increase your levels of this protective hormone by exercise and by following a smart diet according to the principles of the Atkins Advantage. Those who eat nuts, whole grains, vegetables, fish and even a small amount of alcohol have higher adiponectin levels.

 

What does all this mean to the person trying to control cravings and manage appetite? Actually, quite a lot. We know from the principles of the Atkins Advantage that the food we eat has a distinct hormonal effect. High-sugar foods trigger insulin, which drives fat into the cells and also contributes to hunger and cravings. Eating foods with higher amounts of fiber and protein has a much better hormonal outcome, keeping blood sugar even and moderating cravings. We know that since ghrelin is released in anticipation of food as well as before an actual meal, spacing our meals out so that our body doesn’t expect a snack every hour or so might be a good strategy to keep this hunger hormone in check.

 

Research is going on right now at Louisiana State’s Pennington Biomedical Research Center in Baton Rouge to try to determine the best kind of eating plan to produce the most feelings of satisfaction and the least feelings of uncontrollable appetite and cravings. So far, one finding has emerged, and it’s right in line with the principles of the Atkins Advantage: If you want to control your appetite, eat low-glycemic meals. “High glycemic foods like refined breads and sugars push the body to refuel,” explained Marlene Most, head of the metabolic kitchen at the Center. “In low-glycemic foods, there is a constant flow of glucose and insulin, so we don’t need to refuel as much.”

 

 

http://www.cdc.gov/nchs/products/pubs/pubd/hestats/obese/obse99.htm

 

 

 

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