Losing weight is the easy part.  Keeping it off is harder, and may cause other health problems, depending on how you do it.
That's the conclusion of a study, published in the Journal of the American Medical Association,  that looked at three very different diets.

Participants who were overweight and obese young adults lost weight, and then had thee different diets:  low fat (60% energy from carbohydrate, 20% fat, 20% protein)  or low carbs  (40%carbohydrate, 40% fat, 20% protein) or VERY low carbs (10% carbs, 60% fat, 30% protein).  Conclusion, according to our researcher and SUNY Upstate Psychologist Dr. Rich O'Neill: the two extremes significantly  increased the chance of cardiovascular disease, while the one in the middle (a Mediterranian style diet with focus on fish and poultry, whole grains, and less sugar, kept the system healthier.