Does astaxanthin cause weight gain?

I can only speak for myself, but my weight has been completely stable while using it. I am not an expert so I can't say how it affects everyone. Maybe monitor your weight for a couple of weeks to see.

Please get your thyroid and basic parameters checked if you are suddenly gaining weight. I once ignored my sudden weight changes thinking it was just diet, and it turned out to be a bigger issue. Don't blame the supplement without a proper doctor's consult.

As a diabetic, I track everything I put in my body very closely. I have been using astaxanthin for its antioxidant benefits and my sugar levels and weight have been totally fine. Just ensure your overall diet is balanced.

No, it doesn't cause weight gain at all. You can take it without worrying.

I take it daily and my weight hasn't shifted even by a gram. Since it's just an antioxidant derived from algae, it doesn't have calories to make you gain weight. Keep your daily meals clean and you will be fine.