"Although this is a reasonable hypothesis, empirical data indicate no consistent negative association between ambitious goals and program completion or weight loss," write the study authors.

"Indeed, several studies have shown that more ambitious goals are sometimes associated with better weight-loss outcomes."

3. Big, fast weight loss won't stick

Going on a very restrictive diet led to faster weight loss, the study authors found, and dieters did not necessarily gain that weight back, either.

"There was no significant difference between the very-low-energy diets and low-energy diets with respect to weight loss at the end of long-term follow-up," write the authors.

4. You won't lose the weight unless you're really ready

"Readiness does not predict the magnitude of weight loss or treatment adherence among persons who sign up for behavioral programs or who undergo obesity surgery," write the study authors.

Why not?

"The explanation may be simple - people voluntarily choosing to enter weight-loss programs are, by definition, at least minimally ready to engage in the behaviors required to lose weight."

5. Kids are losing weight in physical education class