Bulk then cut, but make sure when you bulk, to increase moderately on the calories when you plateau, because the temptation for some, is to, when plateauing, eat big dude calories and a 200lb natural needs what he eats to be that big, whereas someone weighing under 170 needs nowhere near that and you'd convert a lot of the calories to fat, with less being converted, the stronger you get and the more your body needs.
I reccomend, if you can eat 6 times a day, moderate calorie increases when you plateau, to 300 more a day, which is 50g a meal, or however many times you eat, increase calories per meal by 50g, using either of these two methods.
1. 5g protein, 5g carbs, 1g fat, (49 calories).
2. 5g carbs, 3-4g fat, (47-56 calories approx).
Protein only need to be 1.2g per lb realistically and 1.5g max, so when you find you need to increase calories, I'd suggest using the first method the first 2-3 times you increase, then go for the second method thereafter.
If you need to cut at some point, ditch about 10g carbs from each meal and add the calories back from fat. You maintain calories and also spare muscle mass, but create an energy deficeit, which will hopefully force the body to source fat to fill the gap.
I'd do this once, because too little carb can affect mood, bloodsugar level and general energy. Avoid ketotonic type diets with zero carb, as they work for pro bodybuilders, but even doing it for a month like some suggest, when you're trying the "usual" type of cut, is not something I'd recommend.
Hopefully that all makes sense

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