1500 Calories a Day and Holding...
Symptom: You're eating the same number of calories, but you've stopped losing weight.
Underlying Cause: As you become leaner, you burn fewer calories during workouts (and when you're resting, too). "And then there's that darn reproductive function that makes us extremely talented at maintaining our weight," said Jenna Bell-Wilson, who holds a doctorate in exercise science and a master's in nutrition. Why the reproductive hoarding? To safeguard a baby should an egg become fertilized.
The Fix: Eat five to six small meals every three to four hours, depending on your calorie needs. Don't reduce the number of calories you're eating, but rather, spread calories throughout the day to keep your metabolism running strong.
"If you're losing weight by decreasing calories, you're going to reach a point where you can't cut back more without sabotaging nutrients," Bell-Wilson said. (That's why it's important to eat low-cal, nutrient-dense fruits and vegetables.) What's more, when your body is deprived of energy, it can go into starvation mode, slowing your metabolism and making weight loss even more difficult.
Symptom: Constant cravings make it hard for you to pass up old favorites -- yet you know those little nibbles of foods you love may explain why you're at a standstill.
Underlying Cause: You're bored with your diet.
The Fix: Shake up your food choices. Load up on different fruits and vegetables; try some new ways with whole grains or lean protein, and experiment with seasonings. Look to other cultures for inspiration.
And when it comes to satisfying your sweet tooth, stick with one or two staples. Studies show decreasing the variety of high-fat foods you eat can lower your total calories and boost your weight loss. Having a plethora of high-fat options to choose from encourages you to keep eating so you can experience the different sensory qualities of each food. Remember the old adage: less is more.
Symptom: The workout that used to leave you huffing, puffing and sore for days barely makes you break a sweat.
Underlying Cause: Your body has become more efficient and requires less energy to do the same activity. "When you get accustomed to your exercise program, it stops stressing your body," Bell-Wilson said. And when you stop stressing your body, you stop seeing results.
The Fix: Add weights, said Christine Gerbstadt, a physician and registered dietitian. Strength training at least twice a week increases your lean body tissue, metabolic rate and fat-burning potential. In fact, a study published in the Journal of the American Dietetic Association found that women who trained with weights twice a week for 12 weeks reduced their body fat by more than 2.5 percent and increased lean muscle mass more than four pounds -- even without restricting calories.
Increasing the duration and intensity of your workouts is also a good idea. So instead of logging in your regular 30 minutes on the treadmill at a steady 4.5-mph pace, try the treadmill's interval training program or hit the road and take advantage of changes in the terrain. Run in the sand or up hills and use landmarks to signify a sprint or a slow down.
And squeeze in extra calorie burning whenever you get the chance, Gerbstadt advised: getting up to change the television channel, instead of relying on the remote control; pacing while on the phone, and doing squats while waiting for your food to nuke.
Symptom: You want to throw in the towel.
Underlying Cause: The numbers on the scale stop going down or (gasp!) start to creep up and you feel like you'll never reach your goal weight.
The Fix: "It's important for people to understand that plateaus are a natural phenomenon, and they will occur," Gerbstadt said. Instead of wallowing in a pit of despair, arm yourself with a list of strategies to help break through it.
Experts recommend implementing small behavioral changes -- taking a walk around the block after dinner or reducing the amount of dressing on your salad by a teaspoon or two. And challenge yourself to run farther, lift more weights or experiment with a new activity.
"Consider recording your exercise activities in a log to help you stay motivated," Bell-Wilson said.
Then visualize yourself at your goal weight. Studies show that dieters who have a positive attitude about their chances for success are more likely to take the weight off and maintain the loss. Other ideas: Wear a favorite outfit (one you know you look great in and that will elicit compliments), look at photos of yourself at goal weight (if you were there before), donate clothes that are now too big, meditate, call a friend or weight-loss counselor, ask a friend for a compliment, make a small positive change (drink an extra glass of water each day, add more fiber to your diet, try a new vegetable or fruit or substitute a lower calorie version for the full-fat, full-sugar treat).
Amy Paturel is a health writer and a columnist for AOL's Diet and Fitness channels. She holds masters degrees in nutrition and public health, both from Tufts University in Boston, Mass.