But what rules can you break and still lose weight?
On "The Early Show," CBS News Medical Correspondent Dr. Jennifer Ashton shared some of the most common diet rules that you can break - within reason -- without guilt.
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Video Series: Dr. Ashton's Health and Wellness
Diet Rule: No Midnight Snacks
Your calories aren't on a clock. It's not necessarily when you eat, but how much you eat during the day -- if you're keeping to a healthy calorie count and spreading them throughout the day, go ahead and eat late into the evening hours if you're within your limits. But we aware of portion size -- those who eat late at night sometimes are less likely to count calories. The key is sticking to your calorie balance -- make sure the "calories in" match the calories burned if you want to maintain your weight. If you want to lose weight, you want to make sure that you're burning more than what you're consuming.
Diet Rule: "All Calories are Equal"
All calories are not equal. While it will take the same amount of energy to burn that calorie, some calories will provide you with more nutrition and leave you feeling more full, which means you can get more "bang" for your calories.
For example, you can eat these chips (1/2 serving size is 130 calories) or have a bigger serving of hummus and carrot sticks (2 tablespoons of hummus = 70 calories, 15 baby carrot sticks = 60) for the same amount of calories. You'll get more fiber and vitamins with this snack than with the chips.
Opt for foods that have more fiber and water in them like fruits, vegetables and whole grains.
Diet Rule: Skipping Meals Will Help You Lose
The idea that "skipping meals will help you lose" can be dangerous. Skipping meals means that you will most likely be hungrier the next time you eat and could possibly be adding pounds. Again, shaving off some calories and substituting healthier choices are smart for weight loss -- but, try not to completely skip meals. And do not skip breakfast. Research shows eating a good breakfast can aid and maintain weight loss.
Diet Rule: Say "No" to All Carbs
No, your body needs carbs to function. And let's face it, when you block out one food group, you're more likely to ditch the diet and be discouraged. Carbs are used for energy and keeps your body going. When you drop all carbs, you could be missing out on all-important fiber. You want to focus your carbohydrate intake on foods that have more fiber and take longer to break down, also known as "complex carbohydrates." Foods like whole grains, beans, fruits and vegetables. Try to stay away from added or refined sugars, which could add empty calories.
Diet Rules You Should Always Follow
The golden rule of losing weight is that you're burning more calories than you're consuming. Don't look for fast fixes. Make weight loss and maintenance more of a lifestyle change. It's OK to lose weight "gradually and steadily" because crash diets often lead to less success.