Yo-yo diet may increase your risk of heart disease and premature death.  

Scale and Tape Measure

A number is just a number, but if your weight yo-yos up and down, losing weight may be bad for your health.  I am not talking about the daily fluctuations that occur in all of us.  Most weight fluctuations are normal.  Personally, my weight has varied in a day by up to 2-3 pounds.  It is virtually impossible to gain 3 pounds of body weight in a day, but you can water weight on the scale that is equal to 3-5 pounds or more in a couple of days.   

Obesity is tied to many chronic medical conditions that are deleterious to your health.  Too much weight increases your risk for diabetes type 2, high blood pressure, heart disease, degenerative arthritis, and more.  Almost all experts will agree that weight loss is good for your health if you are overweight or obese, but can weight loss be bad for your health.    

A new study looked at weight fluctuation and coronary artery disease.  The study looked at body weight changes for over 9500 subjects.  The researchers found that a variation of fewer than 2-kilograms in overweight or obese subjects resulted in a significant increase in heart disease by 4%.  There was not associated risk for those of healthy weight who had a 2-kilogram variation of their weight.

The bottom line: Yo-yo diets or fluctuation is weight is terrible for your health, but some weight fluctuation is normal.  If the scale shows five or more pounds difference in 1-2 days,  the change in weight more likely due to water weight.  I would guess that being obese is worse for you health, but further studies are needed to confirm this.  I recommend that you lose the weight and stay at a healthy weight.  If you cannot attain a healthy weight and trying to do so will create a yo-yo effect, it might be healthier not to lose weight at all, but more research is needed.