Most everyone is mostly right here.
Carbs are about insulin management. Slower carbs, are better, except post workout (I'm drinking orange juice as I write this).
When I diet to get very lean, I'll eat about 75 to 150 grams of carbs a day (with two a day workouts), and occassionally go as high as 600.
If I'm seeking to gain, I'll do as much as 1200 grams of carbs. Carbs are protein sparing.
Your body, by evolution, goes into famine mode if your diet is too restrictive, and...becomes a fat storing machine. However.... you can make yourself less, or more, accustomed to carbs. Too much insulin / sugar is not healthy, and WILL make you fat, but, if you lift every day, those carbs will burn right out under load.
To get very lean, one often has to throw in cheat days to keep the metabolic rate up, even with T3/T4, and AAS.
Generally speaking, you'll want to eat small meals often and train most days, say...taking 1 day off in every 7, and, on that day not lifting, but, doing something like HIIT. Age, and rest (sleep) levels affect all this, too.
I can get lean on as much as 600 grams of carbs as day. Because carbs drive insulin (the shuttle hormone) carbs, are, by default, anabolic. When you come to an understand of how to manage insulin, and realize its role in the shuttle..you'll make great gains. That intake amount point varies on a whole list of factors: genetics, current lean muscle mass, type of exercise, stress levels, t3, stimulant use, etc., ad nauseam..I.e., what's right for me may be completely off for you.
If your goal is mass, or exercise performance, carbs are a very important part of the equation. Where your point is, though, may be completely different from someone else. If you are weight training, and doing HIIT, you NEED to gobble down calories to make gains. If you are casually lifting 3 days a week, well..then you have to cycle carbs on the days you exercise. Specifically, bringing up carbs, post workout, and leaving them down when you're inactive. (Insulin, glycogen, anabolism, are what you need to study.)
While you're at it, research the role of poly and mono fat. It's important to your cardiac health, and HIIT is essential in conditioning your heart.
I'm 54, and...I can take my heart rate to 115% for 20 minutes. You can improve your heart health in as little as 7 4 minutes sessions a week, and improve your EKG, in as few as four HIIT sessions. For intense exercise, you NEED carbs, to a degree, or you'll drag. If you're a competitive bodybuilder, dragging yourself through lifting and cardio can become very challenging on low carbs, but, it's how folks get so very lean (stimulants and magic mix). If you're training for gains... EAT. Just stay away from the really fast / sweet stuff, except for post workout. Post workout, load with 30 to 60 gram of fast carbs, and about 60 grams of slow carbs, on up to 400 grams of slow carbs. You'll have your best luck fueling up post workout with plenty of water, some fast carbs, about 40 to 60 grams of protein. You should study up on on how to get good fat in there, too. Non-post workout meals, you should be getting good fats, and not so heavy on the carbs.
It is realistic to gain a pound a week, without doing anything super special. We put 85 pounds on roommate Logan in just 5 months (Logan is a type 1 diabetic and has an insulin pump, so... we had lemons and made lemonade.)