Unless you have a specific medical condition like Prader-Willi Syndrome, genetics play a very small role in the development of obesity. Environment is a much more prominent factor- the majority of families that are all obese are not that way because of genetics, but because of habits passed down through generations. A vast majority of individuals who are obese are that way because of the amount of food they eat, the type of food they eat, and the lifestyle they lead (sedentary). There are some conditions, like hypothyroidism, that will affect your metabolism and cause it to "slow down." However, this will not cause you to become obese if you're eating a healthy diet (overweight, yes, but not obese). It's kind of like the role genetics play in addiction- you can be pre-disposed to be an addict, but if you never use, you won't become one.

"Calories in, calories out" is not a myth or something made up to "fat shame" individuals. It's science. If you burn more calories than you take in, and live on a calorie deficit, you will lose weight. I have not seen a single clinical study where this has been disproven. What does exist are multiple studies that show that individuals regularly underestimate the calories that they take in and portion sizes (this is especially common in the US). There are many people who will claim they only eat 500-800 calories a day that are actually consuming a couple thousand.

What many people mistake for genetics in the role of weight gain is actually a mental health issue. Genetics don't make you binge on food when you're anxious or depressed. Depression and anxiety do. It is entirely possible to gain control of your weight, but it might take time and a lot of work, plus some discomfort. Many people give up after a couple days or weeks when they don't see drastic changes, claiming that it just doesn't work and thinking that their bodies must be special or unique and not play by the rules. Being hungry all the time isn't fun, but it is entirely possible to find a lifestyle diet (not a trend or fad diet or some sort of "cleanse") that will help you feel satisfied without eating 4000 calories a day. And if you stick to it, and don't return to your old habits, you will lose weight. Period.

I've had countless patients spend hours online researching incredibly rare genetic conditions (if you're 25 years old, I can comfortably say that you do not have Tay-Sachs) and passionately arguing, trying to find any excuse possible that will explain why they can't lose weight, and shouldn't even try. I've also had many patients work hard, enact change in their lives, and find success. These patients usually end up admitting that they were lying to themselves for years about the amount of control they had over their body. There are people who can eat whatever they want, and not gain a pound. It's not fair, but it's reality. Then there are others who have to constantly watch what they eat, because even a small slip-up will result in weight gain. That's not fair either, but it is what it is.

You are responsible for your weight, and you have the ability to change your lifestyle. Stop looking for excuses. The sooner you take accountability of the issue and identify what it really is that is motivating you to live the way you do, the sooner you can take steps to change things. But that involves being honest with yourself. It can be done.