Too many people drop dairy from their diets when they try to lose weight, he says. "They're shooting themselves in the foot when they do that. Dairy products contain literally hundreds of compounds that all have a positive effect on human health and enhance the fat-burning machinery," he explains.

Milk The Why & How

"When we cut dairy products, we send the body a signal, to make more fat," says Zemel. "When your body is deprived of calcium, it begins conserving calcium. That mechanism prompts your body to produce higher levels of a hormone called calcitriol, and that triggers an increased production of fat cells."

High levels of calcitriol "tell" fat cells to store themselves in the body, he says. This increase in calcitriol also "tells" fat cells to expand, he says. "So you're getting bigger, fatter fat cells. And a lot of big, fat cells makes for a big, fat person."

Extra calcium in your diet suppresses this hormone, he says. Your body breaks down more fat, and fat cells become leaner, trimmer. A high-dairy diet can boost weight loss by about 70%.

But wait, there's more. "It turns out that milk, cheese, and yogurt are much more effective than calcium supplements or calcium-fortified foods," Zemel says. Why? Dairy products are a complex collection of compounds. Like phytochemicals found in fruits and vegetables, there's more than vitamins and minerals in dairy products. "They are not classically nutrients, but are recognized as having beneficial effects."

Fat Calories Still Count, But Calcium Will Change Your Body Composition

Dairy isn't a weight-loss miracle, says Zemel. Calories still count. But even if you don't restrict calories, taking in more calcium will change your body composition. You're shifting calories from fat to lean body mass. "On the scales, you may not see a change. But we've seen a loss of body fat," he says.

"We need to think of milk as more than a calcium-delivery vehicle," he says. "It's more than just calcium. It's high-quality protein, a collection of amino acids that provides positive effects on skeleton, muscle, and fat."

Zemel's research holds water, says Lara Hassan, MS, a nutritionist with the Cooper Clinic in Dallas. Indeed, "studies are showing that high calcium increases fat oxidation or fat burning, and that results in greater fat loss, and weight loss if it's a reduced-calorie diet.".

She cites one study in which obese men consumed two cups of low-fat yogurt a day, and made no other changes in their diet. They lost an average of 11 pounds over the course of a year.

Water Heavy Foods Tell Your Brain You're Full

Tomato juice, tomato soup, vegetable soup, water-heavy foods like these seem to trigger receptors in the stomach that tell the brain you're sufficiently fed, says Barbara Rolls, PhD, a professor at Pennsylvania State University and author of The Volumetrics Weight-Control Plan: Feel Full on Fewer Calories.

In fact, satiety, that "I'm full" feeling, is the secret ingredient to weight management. "People don't like to deny themselves. They feel a sense of failure when they deprive themselves."

Broth, soups, and juices, along with whole fruits, vegetables, and grains, are high in fiber and water content, and low in fat and calories. "If you have soup before a meal, it helps control hunger and you eat less," Rolls says. "Low-calorie soup takes the edge off your hunger." Just be careful not to eat rich, cream-based soups, they could add calories to your diet, she says.

When You Add Water Rich Foods, You Add Volume But Few Calories

How it works: Water dilutes the calories in food. You can then eat more for the same calories. When you add water-rich blueberries to your breakfast cereal, or water-rich eggplant to your lasagna, you add food volume but few calories, Rolls explains.

Grapes have more water content than raisins. For a 100-calorie snack, you can eat more grapes than raisins. It's just that simple.

Fat Has Less Water Than Any Food

Fat has less water than any food element at 9 calories per gram, alcohol is next at 7, followed by protein and carbohydrates each at 4, Rolls says.

Want More Examples?

Consider the difference between chocolate milk and a milk chocolate bar. A 1 1/2 ounce milk chocolate bar has 230 calories, while an 8-ounce glass of chocolate milk made with whole milk has 250 calories. For about the same calories, you get a portion that is five times bigger than the chocolate bar.

Add more vegetables, and less pasta and fat, to a pasta dish, and you get more food volume. You see the difference, and feel satisfied when you eat it, she says.

Obese people eat more low-water foods than normal-weight people, big portions of meats, full-fat milk and cheese, fried eggs, high-fat desserts, one study shows. They also ate few high-water foods like salads, fruits, skim milk.

Psychological satisfaction is powerful, she says. "We're talking about dietary changes that people can sustain. If fat content is too low, it doesn't satisfy your hunger. If you don't enjoy foods, you are not in the long run going to sustain the eating pattern. That's where people go wrong, they go too extreme, so they're on the same old dieting roller coaster."

Make The Weight Loss Switch

Rolls' theories are right on the money, says Hassan. "There's a lot of research to back this up. Foods with high water content take longer to eat, and they generally leave people feeling fuller. People feel better when their plate is full and their stomach is full."

Her advice:

Drink two glasses of water or other non-calorie beverage before a meal.

At a restaurant, either eat a small salad or broth-based soup.

At home, fill up half the plate with vegetables, one-fourth with a starch, and one-fourth with protein -- so the dominant part is vegetables. If you want seconds, veggies would be the choice.

Before going to a restaurant, eat a high-volume, low-calorie snack, fat-free milk, a piece of fruit, a cup of light yogurt. "You won't be famished, so you won't eat a whole basket of chips or bread."

If you get the evening munchies, drink bouillon, hot tea, or light cocoa, or have two cups strawberries with light cool whip. "It's a great dessert and only 100 calories," Hassan says.

Tea is calorie-free, has less caffeine than coffee, and is a great source of antioxidants. However, tea won't do much to help weight loss, Hassan tells WebMD. "Sip tea to get full, but I would never tell someone it would boost metabolism."

The bottom line for weight loss, follow a reduced-calorie, healthy eating plan, get regular exercise, and do weight training to increase lean body mass and speed up metabolism, she says.