Dr. Mehmet Oz
Photo: Ben Goldstein/Studio D
The unfortunate truth is that most diets do not succeed, and it's easy to blame that fact on a lack of willpower. But restricting food intake runs counter to the body's natural urges. Our ancestors needed extra calories to survive times of extreme stress (say, a famine), and today, when our stress hormones spike—whether due to job frustration or a fight with our spouse—it's as if we're stranded on the tundra of the last ice age.

The good news is that you can outwit your evolutionary biology by implementing these five rules of successful "waist loss" that I developed with Michael Roizen, MD, for our book YOU: On a Diet.

Rule #1: Spoil Your Dinner

Remember the plant from Little Shop of Horrors, with its demands to "Feed me"? The hormone ghrelin is your body's version of Audrey II, only it gets your attention with stomach growls instead of musical numbers. Once you've started eating, it takes about 30 minutes for ghrelin levels to fall and that "full" feeling to kick in. But if you eat a 100-calorie snack (like a handful of nuts) about a half hour before mealtime, your ghrelin levels will already be subsiding by the time you pick up your fork.

Rule #2: Nix Soft Drinks with Meals

Leptin is a hormone that signals the brain that you can stop eating once your body has stored enough energy from food. Yet fructose (a sugar found in soft drinks) interrupts the feedback loop, preventing your brain from getting the message. Quench your thirst with water instead.

Rule #3: Fill Up on Fiber

The ileum is a part of the small bowel that can squeeze, or "brake," to slow the transit of food through the intestines. When that happens, you get a slow but steady supply of fuel, which keeps you feeling satiated. A high-fiber breakfast triggers this mechanism, because the bowel needs more time to absorb nutrients from fiber. The result: No more 11 a.m. stops at the vending machine.

Rule #4: Eat with Awareness

That means eating at the table, not sprawled across the couch. It also means no zoning out in front of American Idol, checking your BlackBerry, or surfing the Web during meals. Not only will mindful eating increase the satisfaction you get from food but the extra time will allow your ghrelin levels to drop even further as you eat.

Rule #5: Build More Muscle

You may have heard that muscle burns more calories than fat, but did you know that it burns a dozen times more? Aim to walk 10,000 steps a day, and begin a muscle-strengthening program, which will help steel your skeleton as well. Trainer Joel Harper has an excellent 20-minute exercise routine.

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