How realistic is your goal weight?

If the last time you maintained your ideal weight was back in secondary school, you may be due for a reality check.

"The number one reason for diet failure is setting a too-low target weight" says Madelyn Fernstrom, Ph.D, Director of the Weight Management Centre at the University of Pittsburgh Medical Centre.

Being over ambitious can lead to major frustration and backsliding. First make sure your target won't put you in the underweight category (calculate your BMI). Fernstrom also recommends rating your weight-loss effort on a 10 point scale (1 is barely trying).

You should be at a 5, which means you're cutting back, but still leaving room for occasional treat and fitting in regular exercise without feeling overworked.

If you are any higher - ravenous all the time, exhausted after your workouts - renegotiate your goal, she says. Losing 1 kilogram instead of 2 can make all the difference between feeling happy and being miserable.