Why do some people pack on the pounds effortlessly? It’s not always genetics and it’s not always gluttony, and you can’t always blame it on lack of exercise. Indeed, becoming overweight is often a result of some simple and easily correctible bad habits, especially when it comes to dining out. (I know. I used to be a chunky kid)

As we began researching Eat This, Not That! Restaurant Survival Guide, we discovered plenty of egregious examples of super-fattening foods in both America’s supermarkets and our chain restaurants. And we learned that if you simply know what to order and what to avoid, you can shave off pounds effortlessly. For example, does On the Border really need to stuff more than a day’s worth of calories into its Dos XX Fish Tacos? (Remember when fish was healthy?) And shouldn’t Chili’s warn parents when a selection on its kids’ menu comes with 82 grams of fat, like its Pepper Pals Little Chicken Crispers does?

If you know these secrets, the power to eat what you want and still stay slim is in your hands. That's why we created the Eat This, Not That! iPhone app! - it’s like having your own personal nutritionist at your fingertips.

In the meantime, here’s the hard truth: There's more contributing to America's obesity problem than just fattening food. The restaurant industry has spent decades studying human behavior and figuring out all sorts of subliminal ways to make us want to order and eat more. And a lot of those psychological tricks have become ingrained in our behavior.

In a study in the journal Obesity, researchers looked at the habits of people dining at an all-you-can-eat buffet. Those with the highest body mass index (BMI) - a measure of obesity - shared many of the behaviors listed below. Know them so you can take charge of your waistline - and your health.

#1. Overweight people use larger plates.
When offered two plate sizes, 98.6 percent of those with the highest BMI took the larger of the two plates to the buffet. A bigger plate tricks your eye into thinking you’re not eating as much when you stuff more food onto the surface—and into your mouth. Use a smaller plate, get a smaller belly.

Bonus tip: The same principle holds true for drinks, as we've found while researching the upcoming Drink This, Not That! The larger the cup, the bigger your gut.

#2. Overweight people eat while looking at food.
Of those with high BMIs, 41.7 percent took seats that overlooked the buffet, instead of sitting in a booth or facing in a different direction. The sight of food tends to make our minds think we have more work to do, eating-wise. Keep your food stored in the fridge or stashed in the pantry, not out on the countertops.

#3. Overweight people eat with maximum efficiency.
While Chinese buffets offer chopsticks, 91.3 percent of obese patrons opt for forks. That just makes it easier to shovel in the food.

#4. Overweight people clean their plates.
Of those patrons who were the heaviest, 94 percent cleaned their plates so there was nothing left. Ignore Mom’s advice—let a little linger, or take it to go.

#5. Overweight people chew less.
Researchers actually monitored the chewing habits of the buffet-goers and discovered that the heaviest one-third among them chewed their food an average of 11.9 times before swallowing. The middle one-third chewed an average of 14 times, and the leanest one-third chewed 14.8 times.

#6. Overweight people dive in.
The leanest people in the study typically took a lap around the buffet first, to plot out what they wanted to eat. But the more overweight group charged right in; doing so means you may fill up on some less-appealing items, then have to go back to snag that one nosh you have to have but missed the first time.

#7. Overweight people skip breakfast.
A simple habit, but missing this crucial meal raises your risk of obesity by a whopping 450 percent! Start your day with some lean protein and fiber—which will jumpstart your metabolism and keep you full. (An egg sandwich is actually a great choice.)

By David Zinczenko, with Matt Goulding