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Hunger can hit without warning and be all but impossible to ignore. The body's most primal instinct, hunger ensures survival in times of famine, driving us to eat, and eat enough. But in today's world of readily available high-calorie food, hunger can feel like a giant biological conspiracy to ruin your diet.
In fact, hunger isn't completely out of your control, and understanding the complex systems behind what makes you hungry can help you make better decisions about eating. The first thing you need to know? It all starts in the brain, says Dr. Arya Sharma, chair in obesity research and management at the University of Alberta. "If you look at the regulation of hunger, appetite and satiety, all of that happens in the hypothalamus," he says.
The hypothalamus is the region of the brain that produces hormones responsible for things like hunger, mood, sex drive and sleep. "It's the centre, the key regulator of energy balance," he says. Ghrelin, the hunger hormone, is released from your empty stomach and sent to the hypothalamus to tell your brain you need food. Meanwhile, leptin, an appetite-suppressing hormone, is synthesized within fat cells to remind the hypothalamus of the body's existing energy stores. Other substances such as peptide YY and cholecystokinin are released in the intestines, especially in response to fatty foods, to further reduce appetite.
But these hormones are affected by more than what you eat. "Leptin and ghrelin get released in response to a variety of different cues," says Dr. Yoni Freedhoff, medical director of the Bariatric Medical Institute in Ottawa. Here are some typical hunger triggers.
Ever finish a great workout only to scarf down a meal twice your usual size? You're not alone. Sharma explains that the hypothalamus works to protect energy stores, and its natural reaction is to make you want to replace the calories you've burned. "Exercise burns far fewer calories than would be fair," says Freedhoff. "So if you kill yourself in the gym for an hour or two and get really hungry, there's a really good chance you're going to consume more calories than you burned." The good news? Exercise is a well-known cure for stress so even if working up a sweat fuels your appetite, you may be better able to restrain yourself later on.
The holidays are filled with two things: stress and sugar. That's a killer combo, because holiday pressures and family feuds can make you want to devour an entire gingerbread house. Researchers from the University of Texas Southwestern Medical Center found that chronic stress in mice leads to increased levels of hunger-inducing ghrelin. And the stress hormone cortisol affects appetite and triggers fat storage, explains Sharma.
Have a couple glasses of red wine or a holiday cocktail before dinner and suddenly you find yourself eating a little more indulgently. No one's really sure if alcohol makes us hungrier, but it does diminish the inhibitions that make us stop eating. It also causes problems with sleep, which can affect hunger the following day. The other problem with alcohol? It's packed with calories that don't fill us up. Whereas protein and complex carbs make us feel full for a long time, calories from alcohol don't have a satiating effect, says Sharma.
Knowing that fat cells create appetite-suppressing leptin might lead you to believe that hunger shouldn't be a problem for someone who is obese. In fact, a surplus of leptin caused by extra fat cells can make the hypothalamus less sensitive to the hormone. "People who are obese may need more food to get the same feeling of satiation as someone who's thinner," says Freedhoff, though he notes that most of the research on leptin resistance has been done on animals.
Whether you're up late wrapping presents or worrying about tomorrow's family gathering, a sleepless night can lead to a grumbling stomach the next day. Studies show that missing even a few hours of sleep throws off your hunger hormones the next day. For example, a 2012 study in the journal Sleep found that sleep-deficient men experienced a boost of ghrelin (the hunger hormone) while overtired women experienced a reduction in GLP-1 (the satiety hormone), making the munchies harder to control for both. And if you're trying to lose weight, you should note that, according to researchers from the University of Chicago, people who limit their calorie intake lose less fat and feel hungrier when they get insufficient sleep (5.5 hours as opposed to 8.5 hours).
Next time you find yourself finishing off an entire box of chocolates, consider whether the time of month might have added to your appetite. Freedhoff says your body can use an extra 200 to 300 calories in the week before menstruation. "You're building your endometrial lining," he says, "and that takes energy." Sharma adds that hormones associated with menstruation can also act on the hypothalamus, affecting your hunger levels. If you notice an increase in hunger around this time, Freedhoff recommends eating more at breakfast to reduce your risk of splurging later on.
You've probably noticed that the mere sight of a pumpkin pie is enough to get your stomach grumbling. (Just try spending five minutes on Pinterest.) It turns out there's a physiological response in your brain when you see delicious food. A German study published in the journal Obesity showed that when people saw pictures of food, their ghrelin levels increased significantly. Luckily, the reverse works, too! A study in Current Directions in Psychological Science found that imagining a specific (non-food-related) sight or smell can help reduce food cravings. So don't get transfixed by that plate of cookies; try visualizing a Christmas tree and imagining the clean scent of pine to ease your cravings.
The full factor
There's no doubt that hunger can wreak havoc on your waistline, but how can you manage it? Both Dr. Sharma and Dr. Freedhoff say the worst thing people can do for their weight is to let themselves get hungry in the first place. Here's a plan to help you stay satiated – and in control – all day long.
7 a.m: breakfast
Eat a protein-rich breakfast, such as an omelette or toast with nut butter and milk. Freedhoff recommends getting a minimum of 350 calories per meal to prevent hunger, with 25 percent of those calories coming from protein. A 2013 study from the American Journal of Clinical Nutrition showed that eating a high-protein breakfast reduced ghrelin for the entire day and increased appetite-suppressing peptide YY.
10 a.m: morning snack
Snacks are helpful for preventing hunger, says Freedhoff. He suggests 100- to 200-calorie snacks between meals, keeping in mind that 25 percent should still come from protein (think Greek yogurt or a seed mix).
12 p.m: lunch
Start your lunch with a light soup or salad, then wait 15 minutes before moving on to the main course. "Giving your body time to register that there's food in it may help with total dietary consumption for that meal," says Freedhoff. It takes time for your body's signals to turn off your hunger. Plus, some satiety signals, such as peptide YY, are released in the small intestine, meaning you need more time to digest the food in order to release these signals.
3 p.m: afternoon snack
Having a 100- to 200-calorie snack will help you get by until dinner, but avoid making that snack a gingerbread latte. "Liquid calories are not filling like solid calories are," says Freedhoff.
6 p.m: dinner
If you're having a glass of wine with dinner, don't start drinking while you cook. Waiting until you're well into your dinner to have your first sip will ensure the alcohol doesn't increase your appetite during the meal.
10 p.m: bedtime
Getting a good night's sleep will do wonders for your appetite. One 2012 report published in the Journal of the Academy of Nutrition and Dietetics showed that women who got four hours of sleep as opposed to seven hours consumed an extra 400 calories.
What if your hunger never stops?
Unfortunately, not all hunger can be satiated by food. "People who are struggling with their weight rarely eat when they're hungry," says Dr. Valerie Taylor, chief of psychiatry at Women's College Hospital. "They eat when they're happy, they eat when they're stressed, they eat when they're bored. It's not about hunger at all."
A variety of psychological factors contribute to this habit. For instance, many of us are trained early in life to view indulgent foods as rewards for good behaviour or as comforts during difficult times. But there are physiological reasons, too. Eating indulgent food sends serotonin (the happiness hormone) to the brain, making you feel good. Those foods also trigger the release of dopamine, which floods the body's reward pathways. (The release of dopamine also occurs during cocaine use.) "Some people are going to eat until that stress passes or until they feel better. And so those signal passages are going to override anything telling them that their stomach's full," says Taylor. For some, counselling may help identify what's really driving the eating, so they can actively unlearn these unhealthy coping mechanisms.
We have more tips on how to stop overeating, including six healthy craving substitutes.
|This content is vetted by medical experts
|This story was originally titled "The Hunger Hub" in the December 2013 issue.
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