Fiber is what you need (lots of studies are very unambiguous about a high fiber diet lowering incidence of heart disease and colo-rectal cancers) , and it can be difficult to get on Keto, because frankly the easiest source of it is legumes. The recommended fiber intake is about 30g per day which is hard even if you can eat carbs. Keto does actually promote attempting to get fiber in your diet as a counterpoint to carb intake but you're basically cutting off the main sources of it (there's only so many green vegetables you can cram in your maw in a day)
I've done Keto. As a weight loss program it's very effective. I'd actually recommend using Keto to get towards a weight goal then migrating to a high fiber diet disregarding the carbs once you've reached your goal. It's unlikely you'll put on weight at that point (you'll put on a wee bit of water weight), because to eat 30g of fiber per day you're basically using oats, certain fruits, legumes, green vegetables and root veg as a base, so there's a natural cleanness to the diet especially if you take the lessons of keto and avoid sugar as much as possible.
Fiber can be an issue, for sure. I eat these:
for the double whammy of providing well over half of the daily recommended fiber intake (26g for this size) , and also as a way to scratch the sandwich itch by making wraps every now and then.