Such as being physically inactive and eating too much.
It's all about diet.
Genetics are a big factor but it's the hand you're dealt and there's nothing you can do about it.
Poor sleep might not help but nobody gets fat with that as the primary cause.
Exercise is great for health and fitness but way overrated for weight loss.
Walking for an hour burns about 300 cals. That's the equivalent of a Snickers bar which can be eaten in about 2 minutes
It's like what Leroy Colbert says, "If an egg is making you fat, eat half an egg."
Every fat person should write that quote down and tape it to their fridge. Of course, it still wouldn't help because most fat people lack the mental toughness to make behavioral changes of any kind.