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The more times you chew each bite, the fewer calories you'll consume, says new study that proves your mother correct.

If you’re trying to lose weight (and aren’t we all?), here’s a study to chew on:

The more your choppers mash up each bite of food, the less food you’re likely to eat at a meal, Chinese researchers reported recently in the American Journal of Clinical Nutrition.

In other words, Mom was right again, although her advice on this subject might have stemmed more from an exaggerated fear of choking than of having to buy clothes for you in the chubby department. The new study confirms: Don’t wolf down your food. Chew it, then chew it some more.

The latest research involved 16 lean and 14 obese young men. After a 12-hour fast, the volunteers came to the laboratory to eat a typical Chinese breakfast— pork pie, not Cocoa Puffs — while a video camera recorded how frequently they chewed each bite. All of the men were given the same portion and told they could ask for more.

The scientists theorized that the obese men would chew less per bite and, indeed, they were right. And while the size of their bites was similar to that of the lean men, the obese men ended up consuming more calories.

So the researchers, who were from Harbin Medical University, tried another experiment. They brought the men back to the lab and served up pork pie again for breakfast, as much as the men cared to eat. But one day they asked the men to chew each bite 15 times, while another day they asked them to chew 40 times.

Didn’t matter whether the men were obese or lean: They consumed about 12 percent fewer calories when they chewed each bite 40 times than when they chewed 15 times, and they had lower levels of ghrelin, the so-called hunger hormone produced in the stomach.

“Chewing less is a risk factor for obesity,” the scientists conclude, perhaps because increased chewing releases nutrients from food more efficiently. Encouraging people to chew more, they write, could be a valuable tool--along with diet and exercise--for helping people lose weight.

I wondered if that might be biting off more than many people could chew, so I asked Mauro Farella of New Zealand’s University of Otago how hard it would be to get folks to masticate more.

Farella was the senior author on a chewing paper posted Aug. 1 by the Journal of Dental Research. He and his coauthors had theorized that people chew at their own consistent pace, part of their unique “fingerprint of masticatory behavior.” His study didn’t find a link between the pace at which people chewed and how thoroughly they chewed.

“I have no idea about whether it would be possible to teach an individual to slow down or up the chewing pace or to change the duration of chewing before swallowing,” Farella says. In principle, though, he says it might be possible to get people to chew each bite more, because, as Mom knows, we at least have partial control over it.

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Chocolate is better than carrots, for more reasons than the obvious one.

Next time you board a plane, you might want to hand the pilot a chocolate bar, just in case.

That’s because a recent study found that dark chocolate might improve your ability to see in low-contrast situations, such as poor weather.

Not only that, this study adds to previous research that suggests eating chocolate can make your brain sharper. (Don’t you just love these chocolate-is-good-for-you studies? Sign me up.) You may have already heard that dark chocolate can lower your blood pressure and also appears to have a favorable effect on cholesterol levels, platelet function and insulin sensitivity.

The authors of the latest study, from England’s University of Reading, enrolled 30 men and women ages 18 to 25 and tested their vision and thinking skills a couple of hours after they ate a regular-sized chocolate bar.

They took the tests twice, once after eating a dark chocolate bar, and once after eating a white chocolate bar. The difference between the two chocolate bars was the amount of flavanols -- a natural compound in cocoa -- they contained. Of course, the dark chocolate bar contained loads of cocoa flavanols, the white chocolate bar only a trace.

Flavanols, found in high levels in grapes, green and black teas, red wine and apples as well as cocoa, have been getting a lot of good press lately as scientists study their health benefits. Ahh, a jug of red wine, a bar of dark chocolate and thou beside me.

To avoid skewing their results, the researchers fudged when they told their subjects the purpose of the study: If the volunteers knew the focus was on cocoa flavanols, they might do better after eating the dark chocolate because they figured they were supposed to. Instead, study participants thought the researchers were investigating the impact of different kinds of fats.

Turns out the study participants did perform better on the vision tests and on some of the brain function tests after eating the dark chocolate, the authors report in the June issue of Physiology & Behavior.  They attribute their findings to cocoa flavanol’s known ability to increase blood flow to the brain, and they speculate that the stuff might also increase blood flow to the retina of the eye.

The good news is that other research suggests cocoa flavanol’s positive impact on blood flow is even greater in us folks over age 25. So the Reading researchers are conducting a similar study in older volunteers. This time they’ll add caffeine and theobromine to the white chocolate bars to make sure those stimulants from the cacao plant aren’t the real reason for dark chocolate’s brain and vision benefits.

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East Coasters know what we're talking about: It's 3 p.m., and despite your ever-growing, never-shrinking to-do list, all you want to do is curl up in a ball and nap under your desk. But it'll come for you soon enough, West Coasters -- the 3 o'clock crash hits all of us, as Bahar Takhtehchian of Shape magazine explained to Kathie Lee Gifford and Hoda Kotb on TODAY this morning.

Here are Takhtehchian's tips:

Move it! Try swapping out your desk chair for a stability ball, or do a couple of bicep curls. (No, really.) The physical activity will wake up your body and your brain.

Avoid a sugary snack. It'll just make you more tired. Instead, try fresh fruit, some low-fat cheese or applesauce.

Stay hydrated. This means stay away from coffee or other caffeinated beverages, which will provide a quick energy boost, and then you'll crash. Plus, the caffeine will dehydrate you. Gulp down water or caffeine-free tea instead.

Watch the video for more ideas. How do you beat the 3 p.m. slump? Leave a comment with your secrets.

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Smaller forks may actually make you eat more when dining out, counterintuitive new research shows.

Using a smaller fork at a restaurant may encourage you to eat a larger portion than a larger fork, a study shows. You might think a smaller utensil would reduce consumption, but it actually increased it when dining out.

This new research focused on bite size -- or the amount of food in each mouthful -- which can vary both within a meal and from person to person. Since it's impolite (and disgusting) to peek into someone's mouth while they're chewing, researchers used fork size as a measure of bite size.

The study, published online in the Journal of Consumer Research, evaluated how fork size influenced the amount of food eaten by diners in an Italian restaurant. During two lunches and two dinners, researchers compared how much food was consumed by those given either a large fork, which held 20 percent more food than a regular one, or a small fork, which held 20 percent less.

They weighed the contents of each plate before and after it was served, and also controlled for other factors that can influence restaurant consumption, such as price, whether it was lunch or dinner, and if alcohol or an appetizer was had with the meal.

Diners left more food on the plate when using a large fork rather than a small one -- a pattern opposite what studies have shown for portion size where larger servings or food packages encourage more eating.

"The finding with a large fork is counterintuitive," says Arul Mishra, an associate professor of marketing at the University of Utah in Salt Lake City, and the study's lead author.

Here's another oddity: Scientists ran a similar study asking 81 people to eat a preweighed bowl of pasta salad, but instead of dining out, the participants ate in a lab setting. Volunteers used the same small or large forks from the restaurant study and were told to eat as much as they wanted.

This time, though, participants who ate with a large fork consumed more pasta salad than those using a smaller one -- the reverse of what was seen in a restaurant and similar to results from portion size studies.

Why the difference?

Mishra suspects the lab participants probably did not have a well-defined hunger goal and did not pay money to consume a food of their choice. So they had different motivations than people dining out, who invest more time, effort and money in their meal.

But in a restaurant, fork size only made a difference for larger portions. Faced with a big plate of food, "people don't visually feel that they are making progress toward satiating their hunger goal with a small fork," suggests Mishra, so they consume more.

She says it's unclear how these results apply to home-cooked meals since this wasn't studied. Even so, her advice is to decide for yourself whether you've had enough to eat by tuning into those feeling-full body signals rather than to your brain. External cues -- fork size, plate size, portion size -- can be misleading and lead to overdoing it.

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Paying for groceries with cash may encourage you to go for healthier options.

The pain of paying in cash can curb spending on unhealthy foods, new research suggests. Shelling out your hard-earned moolah appears to put a crimp in buying "vice products," such as cookies, ice cream, and chips.

Using plastic -- either a credit or a debit card -- at the supermarket led to more impulse purchases of these guilty pleasures.

In the first of several experiments, published in the Journal of Consumer Research, researchers looked at register receipts over a six-month period from a random sample of 1,000 loyal shoppers in one-family households at a Northeastern supermarket chain. (They used single-family households to be sure the same person was doing all the food buying, which is less clear in larger families.)

The researchers looked at what types of foods were purchased in 100 different food categories as well as the payment method. Before analyzing the register receipts, they had other consumers rate foods based on whether they perceived them to be healthy or unhealthy, and impulse buys or planned purchases. 

The study found that payment method appeared to weaken impulse control: Shoppers bought more food items considered impulsive and unhealthy when paying by plastic than when ponying up the dough. Researchers also noticed that consumers who shop on weekends were less likely to be impulsive and tended to stick to a list.

"We were surprised to find that debit cards had the same psychological effect as credit cards," says Manoj Thomas, an assistant professor of marketing at Cornell University in Ithaca, N.Y. Although debit cards are equivalent to cash since the money gets deducted from your bank account almost immediately, Thomas says the "mere abstractness of plastic payments can reduce the pain of payment and influence consumer's purchase decisions."

In other words, we don't feel the same sting in the wallet with either type of plastic as we do when peeling off the bucks. But perhaps these spending patterns are more a function of cheapskates versus big spenders?

Researchers investigated this question by observing 125 students doing a computer-simulated shopping task. They observed that tightwads were more likely to buy impulsive products when using a credit card than cash, but payment method had little influence on spendthrifts impulsive buys. Interestingly, payment method had no effect on the purchase of "virtue" products -- healthy foods such as fat-free yogurt or whole grain bread.

"Vice spending is more susceptible to pain of payment," suggests Thomas, the study's lead author. But it's a double-edged sword psychologically: It brings out positive feelings from a visceral desire to consume the product and negatives ones from anticipated regret after eating it.

Virtue products don't elicit these regrets and you can easily justify spending money on them.

So, is a cash-only diet the new secret to a slimmer waistline?

"Those consumers who find it difficult to control their impulsive consumption might find it helpful to use cash instead of plastic," says Thomas. "The self-control related advantages of paying in cash might outweigh the disadvantages for some consumers."

Do you think you make more spontaneous food purchases when paying with plastic?

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Sleepyheads, please refrain from licking your monitor.

Slacking off on shuteye could make it harder for you to resist high-calorie treats and fattening foods, new research found.

Feeling drowsier during the day because you didn't catch enough ZZZs at night may make it easier for you to give in to temptation, suggests a preliminary study to be presented at the 2011 meeting of the Associated Professional Sleep Societies.

In this small study of 12 healthy adults, ages 19 to 45, participants were shown photographs of low- or high-calorie foods over a four-minute period as images of their brains were scanned. Volunteers were told they would be given a memory test afterward to make them focus on the visuals.

Every few seconds new images would flash before participant's eyes including such healthy fare as salads, fresh fish, an apple or orange. They also saw more enticing edibles from strawberry cheesecake and french fries to cheeseburgers and chocolate cake. As a control, researchers sprinkled in shots of trees, rocks, and flowers.

Volunteers also completed questionnaires about how drowsy they were during the day as well as their food likes and dislikes and typical eating habits.

Scientists found that "the sleepier you are, the less the prefrontal cortex -- the inhibitory area of the brain -- is activated when it's shown high-calorie foods," says William Killgore, an assistant professor of psychology at Harvard Medical School and McLean Hospital in Belmont, Mass.

In other words, if you've skimped on sleep, you're less likely to put on the brakes when you're around fattening foods. And you're more likely to reach out and grab that bacon double cheeseburger or dig into a pint of Chunky Monkey.

In the research, participants were not chronically sleep-deprived. They had the usual tiredness that comes from staying up past their bedtime by an hour or two a night. Even this was strongly correlated with less activation in the inhibitory areas of the brain when shown calorie-rich foods.

When you don't get the rest you need, "you might not have the ability to say no to that extra cookie or dessert," points out Killgore, and you're a little more likely to take in a few extra calories a day.

"Even subtle changes in sleep could be having larger effects in ways we hadn't considered, such as appetite, body weight, and food choices," explains Killgore. A little bit of sleep loss adds up and may influence your body shape. 

"It's entirely plausible that with less inhibitory control, you reach for less optimal foods, and this may lead to a lot more weight over a lifetime," Killgore says.

And a fatigue-induced lack of inhibition can extend to behaviors beside eating. Other studies have suggested that being sleep deprived affects a person's ability to plan and think ahead, and skews judgment when assessing risk.

When you're tired during the day, are you more likely to go for junk food?

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When you think you're eating something indulgent, you feel satisfied sooner than when you consume a food that's supposedly better for you, reveals a new study.

Yale University researchers wanted to find out if your frame of mind -- your beliefs and expectations -- while eating a food could influence your body's physiology more than its actual nutritional value. So, they measured levels of ghrelin, a hormone released in the stomach in response to hunger.

When the blood has high levels of ghrelin, the "hunger hormone," it sends signals to the brain to let it know you want food. As you chow down, ghrelin levels decrease, which reduces appetite and makes you feel full.

To see whether ghrelin levels were affected by a person's expectations of a food, they rounded up 46 normal weight or plumper volunteers (ages 18 to 35). Participants were told they would be testing two new milkshakes: One was labeled as a high fat, 620-calorie "indulgent" shake; the other was a no-fat 140-calorie sensible, or "sensi-shake."

The trick was that both were the same 380-calorie french vanilla milkshakes disguised in different packaging.

While volunteers rated the "sensi-shake" as healthier than the "indulgent" shake and had a good-for-you mindset before drinking it, their bodies told a different story. Ghrelin levels were flat or slightly higher while tasting it, suggesting they were not physiologically satisfied with the beverage.

When participants drank the "indulgent" shake, whose label described it as "heaven in a bottle" and the "decadence you deserve," ghrelin levels steeply increased in anticipation of it, followed by a dramatically steep decline after consuming the creamy drink. This indicates they craved the drink more and were more satisfied afterward. Interestingly, though, hunger levels showed little change after either drink. A large drop in ghrelin levels should be accompanied by a large drop in hunger levels.

Researchers had expected that drinking the sensible shake would produce a sharper reduction in ghrelin levels, but the exact opposite occurred.

"The mindset of 'sensibility' or 'restraint' when eating -- no matter what we're eating -- might be compromising our body's physiological response, counteracting our hard work at dieting," says Alia Crum, a clinical psychologist at Yale University in New Haven, Conn., and the study's lead author.

And that's the mindset often adopted when trying to lose or maintain weight. "People should still work to eat healthy," suggests Crum, "but do so in a mindset of indulgence." By this she means believing a food will be enough to indulge your nutritional and hunger needs.

Unhealthy foods that market their healthy virtues (think: multigrain snack chips or chocolate-covered granola bars) may be doubly damaging. Their labels may be misleading and inaccurate but they can also affect people's perception of the food and the body's response to it, explains Crum.

This study appears online in Health Psychology.

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