When your scale weight goes bonkers, you’re tempted to pull out all the stops: eat less, move more, sacrifice a goat, and so on. If it works, it works, except you wouldn’t know which thing actually worked or didn’t work. The better way to know for sure is to make only one change at a time.
Rather than tinker with both your diet and exercise at once, take an honest look at what you’re doing already and make a single, small change to one (but not both). For example, if you’re already eating 1700 calories and working out hard 3 days a week, try adding another day of exercise while keeping calories the same, since for most people it is mentally easier to add something (exercise) than to take away (calories). Assess your progress for at least two weeks before making another call.
Whether you’re trying to lose weight or even fix someone’s PC, establish constants and control very few variables. It’ll help you figure out what you need to do without resorting to excessive measures, or throwing your hands up in the air (and waving them like you just don’t care). It’s a slower process, but your sanity and body will thank you.