7. Ignoring an undiagnosed medical condition
Sometimes the most dedicated dieter won't notice a change in weight after devotion to healthy eating habits and exercise. If you can't lose weight, it's wise to consult with a medical professional. Disorders that affect the thyroid, such as Hashimoto's Disease and Graves' Disease, can make it difficult to lose weight without treatment of the condition itself.

8. Not setting boundaries
Friends and family love you no matter how you look, and that's a blessing. Mom's not intentionally trying to sabotage your efforts when she "supersizes" the calorie-laden pasta dish you loved as a child. But it's often difficult for loved ones to recognize their enabling behaviors unless you point them out tactfully. Let the people close to you know that you've made a lifestyle change, and ask for their cooperation and support.

9. Acquiring unsafe habits
The worst case of self-sabotage is when a frustrated dieter resorts to drastic measures. The use of laxatives, self-induced vomiting (purging), and frank starvation (anorexia) are signs that you need to seek the help of a doctor or mental health professional.