Multitasking while you eat means you won't be as satisfied, a recent study in the American Journal of Clinical Nutrition found. Some of the study's participants ate while playing computer solitaire, while others ate without distraction. The results? The game-players were worse at remembering what they had eaten—and felt significantly hungrier afterward.

At the end of a hot day, it's easy to down a few frozen margaritas or chilled sangrias just to stay cool. But that's packing on hundreds of calories. If you want a cocktail, instead try tequila and seltzer on the rocks. When a drink doesn't take like a Slurpee (we're looking at you, frozen mango-strawber-rita!) you sip more slowly and take in far fewer calories, says nutritionist Stephen Gullo.

In a recent study, ten overweight volunteers went on a diet while sleeping 8.5 hours a night for two weeks and just 5.5 hours per night for another couple of weeks. (During the day, their diet and activity levels were exactly the same.) In both cases, the average weight loss was 6.5 pounds, but when the group slept less, they lost less fat (1.3 pounds versus 3 pounds), and felt hungrier.

Capsaicin, the compound that gives chili peppers their heat, speeds metabolism, according to a recent study led by David Heber, a professor of medicine and director of the Center for Human Nutrition at UCLA. Participants received either placebo pills or flavorless capsaicin supplements daily for four weeks. The supplement group burned more fat for several hours after a meal, and they burned about 100 to 200 more calories per day, says Heber. Bonus: Spicy foods may trigger a feeling of fullness sooner than bland foods.

Thinking through exactly what and when you're going to eat your meals can make you more likely to stick to your diet goals, according to a study in Psychology and Health. In a study designed to encourage healthy eating, all participants ate more fruit for a week, but those who made a concrete plan, wrote it down, and visualized how they were going to carry out the action—when, where, and how they would buy, prepare, and eat fruit—ate twice as much fruit as those who simply tried harder.

Think you can cut your regular mile walk in half because you're wearing toning MBTs or Skechers? Not so fast. Researchers at the University of Wisconsin-La Crosse found no differences in heart rate, calories burned, or muscle activity when study participants wore them versus regular running shoes on a treadmill.

They can cause stomach bloating. (Look for "-ol" endings on ingredients, such as sorbitol.) And it's not just food; even many sugar-free gums and breath mints contain the culprits.

Studies show that caffeine speeds up metabolism, as do coffee's polyphenols, according to researchers from Japan's Kao Corporation. (Just remember that you can undo the effects if your coffee is covered in whipped cream and caramel.)

It's easy to fall off the wagon and stop going to the gym and eating heathfully, but when you need some motivation to stay on track, jump up and down in front of the mirror, nude. "If things are still moving after you've stopped jumping, you'll want to de-jiggle them," says celebrity personal trainer David Kirsch.