How can i prevent large weight fluctuations?

Avoid sudden dieting: Successful dieting requires that a person stick to a plan for months or years, so easier goals & small milestones are good. He must be happy with the foods he gets to eat, so severe calorie restriction is usually unsuccessful. One can cut back on calories enough to lose 1-2 pounds a week, and he will be more likely to stay with that modest type of plan. One-two pounds a week is 50-100 pounds/year!

Sensible diet: And regular prolonged exercise.